[svn-r6252] Purpose:

    Lots of performance improvements & a couple new internal API interfaces.

Description:
    Performance Improvements:
        - Cached file offset & length sizes in shared file struct, to avoid
            constantly looking them up in the FCPL.
        - Generic property improvements:
            - Added "revision" number to generic property classes to speed
                up comparisons.
            - Changed method of storing properties from using a hash-table
                to the TBBT routines in the library.
            - Share the propery names between classes and the lists derived
                from them.
            - Removed redundant 'def_value' buffer from each property.
            - Switching code to use a "copy on write" strategy for
                properties in each list, where the properties in each list
                are shared with the properties in the class, until a
                property's value is changed in a list.
        - Fixed error in layout code which was allocating too many buffers.
        - Redefined public macros of the form (H5open()/H5check, <variable>)
            internally to only be (<variable>), avoiding innumerable useless
            calls to H5open() and H5check_version().
        - Reuse already zeroed buffers in H5F_contig_fill instead of
            constantly re-zeroing them.
        - Don't write fill values if writing entire dataset.
        - Use gettimeofday() system call instead of time() system when
            checking the modification time of a dataset.
        - Added reference counted string API and use it for tracking the
            names of objects opening in a file (for the ID->name code).
        - Removed redundant H5P_get() calls in B-tree routines.
        - Redefine H5T datatype macros internally to the library, to avoid
            calling H5check redundantly.
        - Keep dataspace information for dataset locally instead of reading
            from disk each time.  Added new module to track open objects
            in a file, to allow this (which will be useful eventually for
            some FPH5 metadata caching issues).
        - Remove H5AC_find macro which was inlining metadata cache lookups,
            and call function instead.
        - Remove redundant memset() calls from H5G_namei() routine.
        - Remove redundant checking of object type when locating objects
            in metadata cache and rely on the address only.
        - Create default dataset object to use when default dataset creation
            property list is used to create datasets, bypassing querying
            for all the property list values.
        - Use default I/O vector size when performing raw data with the
            default dataset transfer property list, instead of querying for
            I/O vector size.
        - Remove H5P_DEFAULT internally to the library, replacing it with
            more specific default property list based on the type of
            property list needed.
        - Remove redundant memset() calls in object header message (H5O*)
            routines.
        - Remove redunant memset() calls in data I/O routines.
        - Split free-list allocation routines into malloc() and calloc()-
            like routines, instead of one combined routine.
        - Remove lots of indirection in H5O*() routines.
        - Simplify metadata cache entry comparison routine (used when
            flushing entire cache out).
        - Only enable metadata cache statistics when H5AC_DEBUG is turned
            on, instead of always tracking them.
        - Simplify address comparison macro (H5F_addr_eq).
        - Remove redundant metadata cache entry protections during dataset
            creation by protecting the object header once and making all
            the modifications necessary for the dataset creation before
            unprotecting it.
        - Reduce # of "number of element in extent" computations performed
            by computing and storing the value during dataspace creation.
        - Simplify checking for group location's file information, when file
            has not been involving in file-mounting operations.
        - Use binary encoding for modification time, instead of ASCII.
        - Hoist H5HL_peek calls (to get information in a local heap)
            out of loops in many group routine.
        - Use static variable for iterators of selections, instead of
            dynamically allocation them each time.
        - Lookup & insert new entries in one step, avoiding traversing
            group's B-tree twice.
        - Fixed memory leak in H5Gget_objname_idx() routine (tangential to
            performance improvements, but fixed along the way).
        - Use free-list for reference counted strings.
        - Don't bother copying object names into cached group entries,
            since they are re-created when an object is opened.

        The benchmark I used to measure these results created several thousand
        small (2K) datasets in a file and wrote out the data for them.  This is
        Elena's "regular.c" benchmark.

        These changes resulted in approximately ~4.3x speedup of the
        development branch when compared to the previous code in the
        development branch and ~1.4x speedup compared to the release
        branch.

        Additionally, these changes reduce the total memory used (code and
        data) by the development branch by ~800KB, bringing the development
        branch back into the same ballpark as the release branch.

        I'll send out a more detailed description of the benchmark results
        as a followup note.

    New internal API routines:
        Added "reference counted strings" API for tracking strings that get
            used by multiple owners without duplicating the strings.
        Added "ternary search tree" API for text->object mappings.

Platforms tested:
    Tested h5committest {arabica (fortran), eirene (fortran, C++)
	modi4 (parallel, fortran)}
    Other platforms/configurations tested?
        FreeBSD 4.7 (sleipnir) serial & parallel
        Solaris 2.6 (baldric) serial

87 files changed, 6559 insertions, 3062 deletions

diff --git a/src/H5.c b/src/H5.c
index 13cda68..742cd77 100644
--- a/src/H5.c
+++ b/src/H5.c
@@ -1388,9 +1388,7 @@ H5_bandwidth(char *buf/*out*/, double nbytes, double nseconds)
  *
  * WARNING:	DO NOT CALL ANY HDF5 FUNCTION THAT CALLS FUNC_ENTER(). DOING
  *		SO MAY CAUSE H5_trace() TO BE INVOKED RECURSIVELY OR MAY
- *		CAUSE LIBRARY INITIALIZATIONS THAT ARE NOT DESIRED.  DO NOT
- *		USE THE H5T_*_* CONSTANTS SINCE THEY CALL H5_open() WHICH
- *		INVOKES FUNC_ENTER().
+ *		CAUSE LIBRARY INITIALIZATIONS THAT ARE NOT DESIRED.
  *
  * Return:	void
  *
@@ -1453,7 +1451,7 @@ H5_trace (double *returning, const char *func, const char *type, ...)
     if (H5_debug_g.ttimes) {
         H5_timer_begin(&event_time);
     } else {
-        memset(&event_time, 0, sizeof event_time);
+        HDmemset(&event_time, 0, sizeof event_time);
     }
     
     /* Print the first part of the line.  This is the indication of the
diff --git a/src/H5A.c b/src/H5A.c
index 8f7f0bb..ab180d2 100644
--- a/src/H5A.c
+++ b/src/H5A.c
@@ -275,7 +275,7 @@ H5A_create(const H5G_entry_t *ent, const char *name, const H5T_t *type,
     H5E_clear ();
 
     /* Create the attribute message and save the attribute index */
-    if (H5O_modify(&(attr->ent), H5O_ATTR, H5O_NEW_MESG, 0, attr) < 0) 
+    if (H5O_modify(&(attr->ent), H5O_ATTR, H5O_NEW_MESG, 0, 1, attr) < 0) 
         HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, FAIL, "unable to update attribute header messages");
 
     /* Register the new attribute and get an ID for it */
@@ -635,7 +635,7 @@ H5A_write(H5A_t *attr, const H5T_t *mem_type, const void *buf)
 
     /* Perform data type conversion */
     if (H5T_convert(tpath, src_id, dst_id, nelmts, 0, 0, tconv_buf, bkg_buf,
-                    H5P_DEFAULT)<0) {
+                    H5P_DATASET_XFER_DEFAULT)<0) {
         HGOTO_ERROR(H5E_ATTR, H5E_CANTENCODE, FAIL,
 		    "data type conversion failed");
     }
@@ -650,7 +650,7 @@ H5A_write(H5A_t *attr, const H5T_t *mem_type, const void *buf)
 
     /* Modify the attribute data */
     attr->data=tconv_buf;   /* Set the data pointer temporarily */
-    if (H5O_modify(&(attr->ent), H5O_ATTR, idx, 0, attr) < 0) 
+    if (H5O_modify(&(attr->ent), H5O_ATTR, idx, 0, 1, attr) < 0) 
         HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, FAIL,
 		    "unable to update attribute header messages");
 
@@ -787,7 +787,7 @@ H5A_read(H5A_t *attr, const H5T_t *mem_type, void *buf)
         }
 
         /* Perform data type conversion.  */
-        if (H5T_convert(tpath, src_id, dst_id, nelmts, 0, 0, tconv_buf, bkg_buf, H5P_DEFAULT)<0)
+        if (H5T_convert(tpath, src_id, dst_id, nelmts, 0, 0, tconv_buf, bkg_buf, H5P_DATASET_XFER_DEFAULT)<0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTENCODE, FAIL, "data type conversion failed");
 
         /* Copy the converted data into the user's buffer */
@@ -1223,7 +1223,7 @@ H5A_rename(H5G_entry_t *ent, const char *old_name, const char *new_name)
     found_attr->initialized=TRUE;
 
     /* Modify the attribute message */
-    if (H5O_modify(ent, H5O_ATTR, idx, 0, found_attr) < 0) 
+    if (H5O_modify(ent, H5O_ATTR, idx, 0, 1, found_attr) < 0) 
         HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, FAIL, "unable to update attribute header messages");
    
     /* Close the attribute */
diff --git a/src/H5AC.c b/src/H5AC.c
index dfdf6d4..fa4f1cb 100644
--- a/src/H5AC.c
+++ b/src/H5AC.c
@@ -4,7 +4,7 @@
  *
  *-------------------------------------------------------------------------
  *
- * Created:             hdf5cache.c
+ * Created:             H5AC.c
  *                      Jul  9 1997
  *                      Robb Matzke <matzke@llnl.gov>
  *
@@ -103,7 +103,7 @@ H5AC_init_interface(void)
     assert(H5P_CLS_DATASET_XFER_g!=(-1));
 
     /* Get the dataset transfer property list class object */
-    if (NULL == (xfer_pclass = H5I_object_verify(H5P_CLS_DATASET_XFER_g, H5I_GENPROP_CLS)))
+    if (NULL == (xfer_pclass = H5I_object(H5P_CLS_DATASET_XFER_g)))
         HGOTO_ERROR(H5E_CACHE, H5E_BADATOM, FAIL, "can't get property list class");
 
     /* Create a new dataset transfer property list */
@@ -206,14 +206,14 @@ H5AC_create(H5F_t *f, int size_hint)
     assert(NULL == f->shared->cache);
     if (size_hint < 1) size_hint = H5AC_NSLOTS;
 
-    if (NULL==(f->shared->cache = cache = H5FL_ALLOC(H5AC_t,1)))
+    if (NULL==(f->shared->cache = cache = H5FL_CALLOC(H5AC_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     cache->nslots = size_hint;
-    cache->slot = H5FL_ARR_ALLOC(H5AC_info_ptr_t,cache->nslots,1);
+    cache->slot = H5FL_ARR_CALLOC(H5AC_info_ptr_t,cache->nslots);
     if (NULL==cache->slot)
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 #ifdef H5AC_DEBUG
-    if ((cache->prot = H5FL_ARR_ALLOC(H5AC_prot_t,cache->nslots,1))==NULL)
+    if ((cache->prot = H5FL_ARR_CALLOC(H5AC_prot_t,cache->nslots))==NULL)
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 #endif /* H5AC_DEBUG */
 
@@ -341,13 +341,13 @@ H5AC_find_f(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
 {
     unsigned                idx;
     herr_t                  status;
-    void                   *thing = NULL;
+    void                   *thing;
     H5AC_flush_func_t       flush;
-    H5AC_info_t           **info = NULL;
-    H5AC_t                 *cache = NULL;
+    H5AC_info_t           **info;
+    H5AC_t                 *cache;
     void                   *ret_value;          /* Return value */
 
-    FUNC_ENTER_NOAPI(H5AC_find, NULL);
+    FUNC_ENTER_NOAPI(H5AC_find_f, NULL);
 
     assert(f);
     assert(f->shared->cache);
@@ -355,6 +355,8 @@ H5AC_find_f(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
     assert(type->load);
     assert(type->flush);
     assert(H5F_addr_defined(addr));
+
+    /* Get local copies of information */
     idx = H5AC_HASH(f, addr);
     cache = f->shared->cache;
     info = cache->slot + idx;
@@ -362,18 +364,18 @@ H5AC_find_f(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
     /*
      * Return right away if the item is in the cache.
      */
-    if ((*info) && (*info)->type == type && H5F_addr_eq((*info)->addr, addr)) {
+    if ((*info) && H5F_addr_eq(addr,(*info)->addr)) {
+        /* Sanity check that the object in the cache is the correct type */
+        assert((*info)->type==type);
+
+#ifdef H5AC_DEBUG
         cache->diagnostics[type->id].nhits++;
+#endif /* H5AC_DEBUG */
         HGOTO_DONE(*info);
     }
+#ifdef H5AC_DEBUG
     cache->diagnostics[type->id].nmisses++;
-
-    /*
-     * Fail if the item in the cache is at the correct address but is
-     * of the wrong type.
-     */
-    if ((*info) && (*info)->type && (*info)->type != type && H5F_addr_eq((*info)->addr, addr))
-        HGOTO_ERROR(H5E_CACHE, H5E_BADTYPE, NULL, "internal error (correct address, wrong type)");
+#endif /* H5AC_DEBUG */
 
 #ifdef H5AC_DEBUG
     /*
@@ -403,7 +405,9 @@ H5AC_find_f(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
      * Free the previous cache entry if there is one.
      */
     if (*info) {
+#ifdef H5AC_DEBUG
         H5AC_subid_t type_id=(*info)->type->id;  /* Remember this for later */
+#endif /* H5AC_DEBUG */
 
         flush = (*info)->type->flush;
         status = (flush)(f, H5AC_dxpl_id, TRUE, (*info)->addr, (*info));
@@ -416,7 +420,9 @@ H5AC_find_f(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, NULL, "unable to flush just-loaded object");
             HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, NULL, "unable to flush existing cached object");
         }
+#ifdef H5AC_DEBUG
         cache->diagnostics[type_id].nflushes++;
+#endif /* H5AC_DEBUG */
     }
 
     /*
@@ -459,37 +465,29 @@ H5AC_compare(const void *_a, const void *_b)
     int                    a = *((const int *) _a);
     int                    b = *((const int *) _b);
     int                    ret_value=0;
+    H5AC_info_t           *slot_a;
+    H5AC_info_t           *slot_b;
 
     /* Use FUNC_ENTER_NOINIT here to avoid performance issues */
     FUNC_ENTER_NOINIT(H5AC_compare);
 
     assert(current_cache_g);
 
-    if(NULL==current_cache_g->slot[a] || NULL == current_cache_g->slot[b]) {
-        if(NULL==current_cache_g->slot[a]) {
-            if (NULL == current_cache_g->slot[b]) {
-                HGOTO_DONE(0);
-            } else
-                HGOTO_DONE(-1);
-        }
-        else {
-            HGOTO_DONE(1);
-        }
-    }
-    else if (NULL == current_cache_g->slot[a]->type) {
-        if (NULL == current_cache_g->slot[b]->type) {
-            HGOTO_DONE(0);
-        } else
-            HGOTO_DONE(-1);
-    } else if (NULL == current_cache_g->slot[b]->type) {
-        HGOTO_DONE(1);
-    } else if (current_cache_g->slot[a]->addr < current_cache_g->slot[b]->addr) {
-        HGOTO_DONE(-1);
-    } else if (current_cache_g->slot[a]->addr > current_cache_g->slot[b]->addr) {
-        HGOTO_DONE(1);
+    /* Create aliases for slots */
+    slot_a=current_cache_g->slot[a];
+    slot_b=current_cache_g->slot[b];
+
+    assert(slot_a);
+    assert(slot_b);
+    assert(slot_a->type);
+    assert(slot_b->type);
+
+    if (slot_a->addr < slot_b->addr) {
+        ret_value=(-1);
+    } else if (slot_a->addr > slot_b->addr) {
+        ret_value=1;
     }
 
-done:
     FUNC_LEAVE(ret_value);
 }
 #endif
@@ -524,21 +522,23 @@ done:
 herr_t
 H5AC_flush(H5F_t *f, const H5AC_class_t *type, haddr_t addr, hbool_t destroy)
 {
-    unsigned                   i;
+    unsigned                i;
     herr_t                  status;
     H5AC_flush_func_t       flush=NULL;
     H5AC_info_t           **info;
 #ifdef H5AC_SORT_BY_ADDR
     int                   *map = NULL;
 #endif /* H5AC_SORT_BY_ADDR */
-    unsigned                   nslots;
-    H5AC_t                 *cache = NULL;
+    unsigned               nslots;
+    H5AC_t                 *cache;
     herr_t ret_value=SUCCEED;      /* Return value */
 
     FUNC_ENTER_NOAPI(H5AC_flush, FAIL);
 
     assert(f);
     assert(f->shared->cache);
+
+    /* Get local copy of this information */
     cache = f->shared->cache;
 
     if (!H5F_addr_defined(addr)) {
@@ -549,7 +549,7 @@ H5AC_flush(H5F_t *f, const H5AC_class_t *type, haddr_t addr, hbool_t destroy)
          * Sort the cache entries by address since flushing them in
          * ascending order by address may be much more efficient.
          */
-        if (NULL==(map=H5FL_ARR_ALLOC(int,cache->nslots,0)))
+        if (NULL==(map=H5FL_ARR_MALLOC(int,cache->nslots)))
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
         for (i = nslots = 0; i < cache->nslots; i++) {
             if (cache->slot[i]!=NULL)
@@ -581,7 +581,9 @@ H5AC_flush(H5F_t *f, const H5AC_class_t *type, haddr_t addr, hbool_t destroy)
                 continue;
 #endif /* H5AC_SORT_BY_ADDR */
             if (!type || type == (*info)->type) {
+#ifdef H5AC_DEBUG
                 H5AC_subid_t type_id=(*info)->type->id;  /* Remember this for later */
+#endif /* H5AC_DEBUG */
 
                 flush = (*info)->type->flush;
 
@@ -592,20 +594,16 @@ H5AC_flush(H5F_t *f, const H5AC_class_t *type, haddr_t addr, hbool_t destroy)
                 } /* end if */
                 else
                     status = (flush)(f, H5P_DATASET_XFER_DEFAULT, destroy, (*info)->addr, (*info));
-                if (status < 0) {
-#ifdef H5AC_SORT_BY_ADDR
-                    map = H5FL_ARR_FREE(int,map);
-#endif /* H5AC_SORT_BY_ADDR */
+                if (status < 0)
                     HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "unable to flush cache");
-                }
+
+#ifdef H5AC_DEBUG
                 cache->diagnostics[type_id].nflushes++;
+#endif /* H5AC_DEBUG */
                 if (destroy)
                     (*info)= NULL;
             }
         }
-#ifdef H5AC_SORT_BY_ADDR
-        map = H5FL_ARR_FREE(int,map);
-#endif /* H5AC_SORT_BY_ADDR */
 
         /*
          * If there are protected object then fail.  However, everything
@@ -616,9 +614,10 @@ H5AC_flush(H5F_t *f, const H5AC_class_t *type, haddr_t addr, hbool_t destroy)
     } else {
         i = H5AC_HASH(f, addr);
         if (cache->slot[i] && (!type || cache->slot[i]->type == type) &&
-            H5F_addr_eq(cache->slot[i]->addr, addr)) {
-
+                H5F_addr_eq(addr,cache->slot[i]->addr)) {
+#ifdef H5AC_DEBUG
             H5AC_subid_t type_id=cache->slot[i]->type->id;  /* Remember this for later */
+#endif /* H5AC_DEBUG */
 
             /*
              * Flush just this entry.
@@ -627,13 +626,20 @@ H5AC_flush(H5F_t *f, const H5AC_class_t *type, haddr_t addr, hbool_t destroy)
             if ((flush)(f, H5AC_dxpl_id, destroy, cache->slot[i]->addr,
 			     cache->slot[i]) < 0)
                 HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "unable to flush object");
+#ifdef H5AC_DEBUG
             cache->diagnostics[type_id].nflushes++;
+#endif /* H5AC_DEBUG */
             if (destroy)
                 cache->slot[i]= NULL;
         }
     }
 
 done:
+#ifdef H5AC_SORT_BY_ADDR
+    if(map!=NULL)
+        map = H5FL_ARR_FREE(int,map);
+#endif /* H5AC_SORT_BY_ADDR */
+
     FUNC_LEAVE(ret_value);
 }
 
@@ -662,10 +668,10 @@ done:
 herr_t
 H5AC_set(H5F_t *f, const H5AC_class_t *type, haddr_t addr, void *thing)
 {
-    unsigned                   idx;
-    H5AC_flush_func_t       flush=NULL;
-    H5AC_info_t           **info = NULL;
-    H5AC_t                 *cache = NULL;
+    unsigned                idx;
+    H5AC_flush_func_t       flush;
+    H5AC_info_t           **info;
+    H5AC_t                 *cache;
     herr_t ret_value=SUCCEED;      /* Return value */
 
     FUNC_ENTER_NOAPI(H5AC_set, FAIL);
@@ -677,6 +683,7 @@ H5AC_set(H5F_t *f, const H5AC_class_t *type, haddr_t addr, void *thing)
     assert(H5F_addr_defined(addr));
     assert(thing);
 
+    /* Get local copy of this information */
     idx = H5AC_HASH(f, addr);
     cache = f->shared->cache;
     info = cache->slot + idx;
@@ -693,19 +700,26 @@ H5AC_set(H5F_t *f, const H5AC_class_t *type, haddr_t addr, void *thing)
 #endif
 
 
+    /* Flush any object already in cache slot */
     if ((*info)) {
+#ifdef H5AC_DEBUG
         H5AC_subid_t type_id=(*info)->type->id;  /* Remember this for later */
+#endif /* H5AC_DEBUG */
 
         flush = (*info)->type->flush;
         if ((flush)(f, H5AC_dxpl_id, TRUE, (*info)->addr, (*info)) < 0)
             HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "unable to flush object");
+#ifdef H5AC_DEBUG
         cache->diagnostics[type_id].nflushes++;
+#endif /* H5AC_DEBUG */
     }
 
     (*info)=thing;
     (*info)->type = type;
     (*info)->addr = addr;
+#ifdef H5AC_DEBUG
     cache->diagnostics[type->id].ninits++;
+#endif /* H5AC_DEBUG */
 
 done:
     FUNC_LEAVE(ret_value);
@@ -737,9 +751,9 @@ herr_t
 H5AC_rename(H5F_t *f, const H5AC_class_t *type, haddr_t old_addr,
 	    haddr_t new_addr)
 {
-    unsigned                   old_idx, new_idx;
-    H5AC_flush_func_t       flush=NULL;
-    H5AC_t                 *cache = NULL;
+    unsigned                old_idx, new_idx;
+    H5AC_flush_func_t       flush;
+    H5AC_t                 *cache;
     herr_t ret_value=SUCCEED;      /* Return value */
 
     FUNC_ENTER_NOAPI(H5AC_rename, FAIL);
@@ -748,6 +762,7 @@ H5AC_rename(H5F_t *f, const H5AC_class_t *type, haddr_t old_addr,
     assert(f->shared->cache);
     assert(type);
 
+    /* Get local copy of this information */
     old_idx = H5AC_HASH(f, old_addr);
     new_idx = H5AC_HASH(f, new_addr);
     cache = f->shared->cache;
@@ -771,7 +786,7 @@ H5AC_rename(H5F_t *f, const H5AC_class_t *type, haddr_t old_addr,
      * new hash value is the same as the old one.
      */
     if (cache->slot[old_idx]->type != type ||
-        H5F_addr_ne(cache->slot[old_idx]->addr, old_addr)) {
+            H5F_addr_ne(cache->slot[old_idx]->addr, old_addr)) {
         HGOTO_DONE(SUCCEED);
     }
     if (old_idx == new_idx) {
@@ -782,13 +797,17 @@ H5AC_rename(H5F_t *f, const H5AC_class_t *type, haddr_t old_addr,
      * Free the item from the destination cache line.
      */
     if (cache->slot[new_idx]) {
+#ifdef H5AC_DEBUG
         H5AC_subid_t type_id=cache->slot[new_idx]->type->id;  /* Remember this for later */
+#endif /* H5AC_DEBUG */
 
         flush = cache->slot[new_idx]->type->flush;
         if ((flush)(f, H5AC_dxpl_id, TRUE, cache->slot[new_idx]->addr,
 			 cache->slot[new_idx]) < 0)
             HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "unable to flush object");
+#ifdef H5AC_DEBUG
         cache->diagnostics[type_id].nflushes++;
+#endif /* H5AC_DEBUG */
     }
 
     /*
@@ -836,9 +855,9 @@ H5AC_protect(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
 	     const void *udata1, void *udata2)
 {
     int                     idx;
-    void                   *thing = NULL;
-    H5AC_t                 *cache = NULL;
-    H5AC_info_t           **info = NULL;
+    void                   *thing;
+    H5AC_t                 *cache;
+    H5AC_info_t           **info;
     void                   *ret_value;          /* Return value */
 
 #ifdef H5AC_DEBUG
@@ -862,6 +881,7 @@ H5AC_protect(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
     assert(type->flush);
     assert(H5F_addr_defined(addr));
 
+    /* Get local copy of this information */
     idx = H5AC_HASH(f, addr);
     cache = f->shared->cache;
     info = cache->slot + idx;
@@ -869,22 +889,20 @@ H5AC_protect(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
     prot = cache->prot + idx;
 #endif /* H5AC_DEBUG */
 
-    if ((*info) && (*info)->type == type && H5F_addr_eq((*info)->addr, addr)) {
+    if ((*info) && H5F_addr_eq(addr,(*info)->addr)) {
+        /* Sanity check that the object in the cache is the correct type */
+        assert((*info)->type==type);
+
         /*
          * The object is already cached; simply remove it from the cache.
          */
+#ifdef H5AC_DEBUG
         cache->diagnostics[(*info)->type->id].nhits++;
+#endif /* H5AC_DEBUG */
         thing = (*info);
         (*info)->type = NULL;
         (*info)->addr = HADDR_UNDEF;
         (*info)= NULL;
-
-    } else if ((*info) && (*info)->type && H5F_addr_eq((*info)->addr, addr)) {
-        /*
-         * Right address but wrong object type.
-         */
-        HGOTO_ERROR(H5E_CACHE, H5E_BADTYPE, NULL, "internal error");
-
     } else {
 #ifdef H5AC_DEBUG
         /*
@@ -902,7 +920,9 @@ H5AC_protect(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
          * Load a new thing.  If it can't be loaded, then return an error
          * without preempting anything.
          */
+#ifdef H5AC_DEBUG
         cache->diagnostics[type->id].nmisses++;
+#endif /* H5AC_DEBUG */
         if (NULL == (thing = (type->load)(f, H5P_DATASET_XFER_DEFAULT, addr, udata1, udata2)))
             HGOTO_ERROR(H5E_CACHE, H5E_CANTLOAD, NULL, "unable to load object");
     }
@@ -963,11 +983,11 @@ done:
 herr_t
 H5AC_unprotect(H5F_t *f, const H5AC_class_t *type, haddr_t addr, void *thing)
 {
-    unsigned                   idx;
-    H5AC_flush_func_t       flush=NULL;
-    H5AC_t                 *cache = NULL;
-    H5AC_info_t           **info = NULL;
-    herr_t                      ret_value=SUCCEED;      /* Return value */
+    unsigned                idx;
+    H5AC_flush_func_t       flush;
+    H5AC_t                 *cache;
+    H5AC_info_t           **info;
+    herr_t                  ret_value=SUCCEED;      /* Return value */
 
     FUNC_ENTER_NOAPI(H5AC_unprotect, FAIL);
 
@@ -979,6 +999,7 @@ H5AC_unprotect(H5F_t *f, const H5AC_class_t *type, haddr_t addr, void *thing)
     assert(H5F_addr_defined(addr));
     assert(thing);
 
+    /* Get local copy of this information */
     idx = H5AC_HASH(f, addr);
     cache = f->shared->cache;
     info = cache->slot + idx;
@@ -988,13 +1009,17 @@ H5AC_unprotect(H5F_t *f, const H5AC_class_t *type, haddr_t addr, void *thing)
      * better not be another copy of the protected object.
      */
     if (*info) {
+#ifdef H5AC_DEBUG
         H5AC_subid_t type_id=(*info)->type->id;  /* Remember this for later */
+#endif /* H5AC_DEBUG */
 
         assert(H5F_addr_ne((*info)->addr, addr));
         flush = (*info)->type->flush;
         if ((flush)(f, H5AC_dxpl_id, TRUE, (*info)->addr, (*info)) < 0)
             HGOTO_ERROR(H5E_CACHE, H5E_CANTFLUSH, FAIL, "unable to flush object");
+#ifdef H5AC_DEBUG
         cache->diagnostics[type_id].nflushes++;
+#endif /* H5AC_DEBUG */
     }
 #ifdef H5AC_DEBUG
     /*
diff --git a/src/H5ACprivate.h b/src/H5ACprivate.h
index 44d4ca8..d587df6 100644
--- a/src/H5ACprivate.h
+++ b/src/H5ACprivate.h
@@ -99,12 +99,14 @@ typedef struct H5AC_t {
     H5AC_prot_t *prot;		/*the protected slots		     */
 #endif /* H5AC_DEBUG */
     int	nprots;			/*number of protected objects	     */
+#ifdef H5AC_DEBUG
     struct {
 	unsigned	nhits;			/*number of cache hits		     */
 	unsigned	nmisses;		/*number of cache misses	     */
 	unsigned	ninits;			/*number of cache inits		     */
 	unsigned	nflushes;		/*number of flushes to disk	     */
     } diagnostics[H5AC_NTYPES];		/*diagnostics for each type of object*/
+#endif /* H5AC_DEBUG */
 } H5AC_t;
 
 #ifdef H5_HAVE_PARALLEL
@@ -133,6 +135,10 @@ H5_DLL herr_t H5AC_set(H5F_t *f, const H5AC_class_t *type, haddr_t addr,
 			void *thing);
 H5_DLL herr_t H5AC_debug(H5F_t *f);
 
+/* This seems to be slower than just calling H5AC_find_f, which performs the
+ * cache lookup also. - QAK
+ */
+#ifdef OLD_WAY
 #define H5AC_find(F,TYPE,ADDR,UDATA1,UDATA2)				      \
    ((F)->shared->cache->slot[H5AC_HASH(F,ADDR)]!=NULL &&	      \
     ((F)->shared->cache->slot[H5AC_HASH(F,ADDR)]->type==(TYPE) &&	      \
@@ -140,6 +146,7 @@ H5_DLL herr_t H5AC_debug(H5F_t *f);
     ((F)->shared->cache->diagnostics[(TYPE)->id].nhits++,		      \
      (F)->shared->cache->slot[H5AC_HASH(F,ADDR)]) :		      \
     H5AC_find_f(F, TYPE, ADDR, UDATA1, UDATA2))
+#endif /* OLD_WAY */
      
 #endif /* !_H5ACprivate_H */
 
diff --git a/src/H5B.c b/src/H5B.c
index 700cf3f..a0386b0 100644
--- a/src/H5B.c
+++ b/src/H5B.c
@@ -212,7 +212,7 @@ H5B_create(H5F_t *f, const H5B_class_t *type, void *udata,
     size = H5B_nodesize(f, type, &total_native_keysize, sizeof_rkey);
     if (HADDR_UNDEF==(*addr_p=H5MF_alloc(f, H5FD_MEM_BTREE, (hsize_t)size)))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "file allocation failed for B-tree root node");
-    if (NULL==(bt = H5FL_ALLOC(H5B_t,1)))
+    if (NULL==(bt = H5FL_CALLOC(H5B_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for B-tree root node");
     bt->type = type;
     bt->sizeof_rkey = sizeof_rkey;
@@ -222,10 +222,10 @@ H5B_create(H5F_t *f, const H5B_class_t *type, void *udata,
     bt->left = HADDR_UNDEF;
     bt->right = HADDR_UNDEF;
     bt->nchildren = 0;
-    if (NULL==(bt->page=H5FL_BLK_ALLOC(page,size,1)) ||
-            NULL==(bt->native=H5FL_BLK_ALLOC(native_block,total_native_keysize,0)) ||
-            NULL==(bt->child=H5FL_ARR_ALLOC(haddr_t,(size_t)(2*H5B_Kvalue(f,type)),0)) ||
-            NULL==(bt->key=H5FL_ARR_ALLOC(H5B_key_t,(size_t)(2*H5B_Kvalue(f,type)+1),0)))
+    if (NULL==(bt->page=H5FL_BLK_CALLOC(page,size)) ||
+            NULL==(bt->native=H5FL_BLK_MALLOC(native_block,total_native_keysize)) ||
+            NULL==(bt->child=H5FL_ARR_MALLOC(haddr_t,(size_t)(2*H5F_KVALUE(f,type)))) ||
+            NULL==(bt->key=H5FL_ARR_MALLOC(H5B_key_t,(size_t)(2*H5F_KVALUE(f,type)+1))))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for B-tree root node");
 
     /*
@@ -234,7 +234,7 @@ H5B_create(H5F_t *f, const H5B_class_t *type, void *udata,
      * translated to native format.
      */
     for (i = 0, offset = H5B_SIZEOF_HDR(f);
-	 i < 2 * H5B_Kvalue(f, type);
+	 i < 2 * H5F_KVALUE(f, type);
 	 i++, offset += bt->sizeof_rkey + H5F_SIZEOF_ADDR(f)) {
 
 	bt->key[i].dirty = FALSE;
@@ -246,9 +246,9 @@ H5B_create(H5F_t *f, const H5B_class_t *type, void *udata,
     /*
      * The last possible key...
      */
-    bt->key[2 * H5B_Kvalue(f, type)].dirty = FALSE;
-    bt->key[2 * H5B_Kvalue(f, type)].rkey = bt->page + offset;
-    bt->key[2 * H5B_Kvalue(f, type)].nkey = NULL;
+    bt->key[2 * H5F_KVALUE(f, type)].dirty = FALSE;
+    bt->key[2 * H5F_KVALUE(f, type)].rkey = bt->page + offset;
+    bt->key[2 * H5F_KVALUE(f, type)].nkey = NULL;
 
     /*
      * Cache the new B-tree node.
@@ -276,54 +276,6 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5B_Kvalue
- *
- * Purpose:	Replaced a macro to retrieve a B-tree key value for a certain
- *              type, now that the generic properties are being used to store
- *              the B-tree values.
- *
- * Return:	Success:	Non-negative, and the B-tree key value is
- *                              returned.
- *
- * 		Failure:	Negative (should not happen)
- *
- * Programmer:	Raymond Lu
- *		slu@ncsa.uiuc.edu
- *		Oct 14 2001
- *
- * Modifications:
- *		Quincey Koziol, 2001-10-15
- *		Added this header and removed unused ret_value variable.
- *-------------------------------------------------------------------------
- */
-int
-H5B_Kvalue(H5F_t *f, const H5B_class_t *type)
-{
-    int btree_k[H5B_NUM_BTREE_ID];
-    H5P_genplist_t *plist;
-    int      ret_value;       /* Return value */
-
-    FUNC_ENTER_NOAPI(H5B_Kvalue, FAIL);
-
-    assert(f);
-    assert(type);
-
-    /* Check arguments */
-    if (NULL == (plist = H5I_object(f->shared->fcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "can't get property list");
-
-    if(H5P_get(plist, H5F_CRT_BTREE_RANK_NAME, btree_k) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get rank for btree internal nodes");
-
-    /* Set return value */
-    ret_value=btree_k[type->id];
-
-done:
-    FUNC_LEAVE(ret_value);
-} /* end H5B_Kvalue() */
-
-
-/*-------------------------------------------------------------------------
  * Function:	H5B_load
  *
  * Purpose:	Loads a B-tree node from the disk.
@@ -364,17 +316,17 @@ H5B_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_type, void *udata)
     assert(type);
     assert(type->get_sizeof_rkey);
 
-    if (NULL==(bt = H5FL_ALLOC(H5B_t,1)))
+    if (NULL==(bt = H5FL_CALLOC(H5B_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     bt->sizeof_rkey = (type->get_sizeof_rkey) (f, udata);
     size = H5B_nodesize(f, type, &total_nkey_size, bt->sizeof_rkey);
     bt->type = type;
     bt->dirty = FALSE;
     bt->ndirty = 0;
-    if (NULL==(bt->page=H5FL_BLK_ALLOC(page,size,0)) ||
-            NULL==(bt->native=H5FL_BLK_ALLOC(native_block,total_nkey_size,0)) ||
-            NULL==(bt->key=H5FL_ARR_ALLOC(H5B_key_t,(size_t)(2*H5B_Kvalue(f,type)+1),0)) ||
-            NULL==(bt->child=H5FL_ARR_ALLOC(haddr_t,(size_t)(2*H5B_Kvalue(f,type)),0)))
+    if (NULL==(bt->page=H5FL_BLK_MALLOC(page,size)) ||
+            NULL==(bt->native=H5FL_BLK_MALLOC(native_block,total_nkey_size)) ||
+            NULL==(bt->key=H5FL_ARR_MALLOC(H5B_key_t,(size_t)(2*H5F_KVALUE(f,type)+1))) ||
+            NULL==(bt->child=H5FL_ARR_MALLOC(haddr_t,(size_t)(2*H5F_KVALUE(f,type)))))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     if (H5F_block_read(f, H5FD_MEM_BTREE, addr, size, dxpl_id, bt->page)<0)
 	HGOTO_ERROR(H5E_BTREE, H5E_READERROR, NULL, "can't read B-tree node");
@@ -398,7 +350,7 @@ H5B_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_type, void *udata)
     H5F_addr_decode(f, (const uint8_t **) &p, &(bt->right));
 
     /* the child/key pairs */
-    for (i = 0; i < 2 * H5B_Kvalue(f, type); i++) {
+    for (i = 0; i < 2 * H5F_KVALUE(f, type); i++) {
 
 	bt->key[i].dirty = FALSE;
 	bt->key[i].rkey = p;
@@ -413,9 +365,9 @@ H5B_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void *_type, void *udata)
 	}
     }
 
-    bt->key[2 * H5B_Kvalue(f, type)].dirty = FALSE;
-    bt->key[2 * H5B_Kvalue(f, type)].rkey = p;
-    bt->key[2 * H5B_Kvalue(f, type)].nkey = NULL;
+    bt->key[2 * H5F_KVALUE(f, type)].dirty = FALSE;
+    bt->key[2 * H5F_KVALUE(f, type)].rkey = p;
+    bt->key[2 * H5F_KVALUE(f, type)].nkey = NULL;
 
     /* Set return value */
     ret_value = bt;
@@ -675,9 +627,9 @@ H5B_split(H5F_t *f, const H5B_class_t *type, H5B_t *old_bt, haddr_t old_addr,
     /*
      * Initialize variables.
      */
-    assert(old_bt->nchildren == 2 * H5B_Kvalue(f, type));
+    assert(old_bt->nchildren == 2 * H5F_KVALUE(f, type));
     recsize = old_bt->sizeof_rkey + H5F_SIZEOF_ADDR(f);
-    k = H5B_Kvalue(f, type);
+    k = H5F_KVALUE(f, type);
 
 #ifdef H5B_DEBUG
     if (H5DEBUG(B)) {
@@ -770,7 +722,7 @@ H5B_split(H5F_t *f, const H5B_class_t *type, H5B_t *old_bt, haddr_t old_addr,
     new_bt->right = old_bt->right;
 
     if (H5F_addr_defined(old_bt->right)) {
-	if (NULL == (tmp_bt = H5AC_find(f, H5AC_BT, old_bt->right, type, udata)))
+	if (NULL == (tmp_bt = H5AC_find_f(f, H5AC_BT, old_bt->right, type, udata)))
 	    HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load right sibling");
 	tmp_bt->dirty = TRUE;
 	tmp_bt->left = *new_addr_p;
@@ -919,7 +871,7 @@ H5B_insert(H5F_t *f, const H5B_class_t *type, haddr_t addr,
     assert(H5B_INS_RIGHT == my_ins);
 
     /* the current root */
-    if (NULL == (bt = H5AC_find(f, H5AC_BT, addr, type, udata)))
+    if (NULL == (bt = H5AC_find_f(f, H5AC_BT, addr, type, udata)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to locate root of B-tree");
     level = bt->level;
     if (!lt_key_changed) {
@@ -929,7 +881,7 @@ H5B_insert(H5F_t *f, const H5B_class_t *type, haddr_t addr,
     }
     
     /* the new node */
-    if (NULL == (bt = H5AC_find(f, H5AC_BT, child, type, udata)))
+    if (NULL == (bt = H5AC_find_f(f, H5AC_BT, child, type, udata)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load new node");
     if (!rt_key_changed) {
 	if (!bt->key[bt->nchildren].nkey &&
@@ -948,7 +900,7 @@ H5B_insert(H5F_t *f, const H5B_class_t *type, haddr_t addr,
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "unable to allocate file space to move root");
 
     /* update the new child's left pointer */
-    if (NULL == (bt = H5AC_find(f, H5AC_BT, child, type, udata)))
+    if (NULL == (bt = H5AC_find_f(f, H5AC_BT, child, type, udata)))
         HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load new child");
     bt->dirty = TRUE;
     bt->left = old_root;
@@ -958,7 +910,7 @@ H5B_insert(H5F_t *f, const H5B_class_t *type, haddr_t addr,
      * at the new location -QAK
      */
     /* Bring the old root into the cache if it's not already */
-    if (NULL == (bt = H5AC_find(f, H5AC_BT, addr, type, udata)))
+    if (NULL == (bt = H5AC_find_f(f, H5AC_BT, addr, type, udata)))
         HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load new child");
 
     /* Make certain the old root info is marked as dirty before moving it, */
@@ -1038,7 +990,7 @@ H5B_insert_child(H5F_t *f, const H5B_class_t *type, H5B_t *bt,
     FUNC_ENTER_NOINIT(H5B_insert_child);
 
     assert(bt);
-    assert(bt->nchildren<2*H5B_Kvalue(f, type));
+    assert(bt->nchildren<2*H5F_KVALUE(f, type));
 
     bt->dirty = TRUE;
     recsize = bt->sizeof_rkey + H5F_SIZEOF_ADDR(f);
@@ -1383,7 +1335,7 @@ H5B_insert_helper(H5F_t *f, haddr_t addr, const H5B_class_t *type,
 	/*
 	 * If this node is full then split it before inserting the new child.
 	 */
-	if (bt->nchildren == 2 * H5B_Kvalue(f, type)) {
+	if (bt->nchildren == 2 * H5F_KVALUE(f, type)) {
 	    if (H5B_split(f, type, bt, addr, idx, split_ratios, udata,
 			  new_node_p/*out*/)<0)
 		HGOTO_ERROR(H5E_BTREE, H5E_CANTSPLIT, H5B_INS_ERROR, "unable to split node");
@@ -1488,7 +1440,7 @@ H5B_iterate (H5F_t *f, const H5B_class_t *type, H5B_operator_t op, haddr_t addr,
     assert(H5F_addr_defined(addr));
     assert(udata);
 
-    if (NULL == (bt=H5AC_find(f, H5AC_BT, addr, type, udata)))
+    if (NULL == (bt=H5AC_find_f(f, H5AC_BT, addr, type, udata)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree node");
     if (bt->level > 0) {
 	/* Keep following the left-most child until we reach a leaf node. */
@@ -1499,8 +1451,8 @@ H5B_iterate (H5F_t *f, const H5B_class_t *type, H5B_operator_t op, haddr_t addr,
 	 * We've reached the left-most leaf.  Now follow the right-sibling
 	 * pointer from leaf to leaf until we've processed all leaves.
 	 */
-	if (NULL==(child=H5FL_ARR_ALLOC(haddr_t,(size_t)(2*H5B_Kvalue(f,type)),0)) ||
-                NULL==(key=H5MM_malloc((2*H5B_Kvalue(f, type)+1)*type->sizeof_nkey)))
+	if (NULL==(child=H5FL_ARR_MALLOC(haddr_t,(size_t)(2*H5F_KVALUE(f,type)))) ||
+                NULL==(key=H5MM_malloc((2*H5F_KVALUE(f, type)+1)*type->sizeof_nkey)))
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 	for (cur_addr=addr, ret_value=0; H5F_addr_defined(cur_addr); cur_addr=next_addr) {
 
@@ -1509,7 +1461,7 @@ H5B_iterate (H5F_t *f, const H5B_class_t *type, H5B_operator_t op, haddr_t addr,
 	     * leave the B-tree node protected during an application
 	     * callback.
 	     */
-	    if (NULL==(bt=H5AC_find (f, H5AC_BT, cur_addr, type, udata)))
+	    if (NULL==(bt=H5AC_find_f (f, H5AC_BT, cur_addr, type, udata)))
 		HGOTO_ERROR (H5E_BTREE, H5E_CANTLOAD, FAIL, "B-tree node");
 	    for (i=0; i<bt->nchildren; i++)
 		child[i] = bt->child[i];
@@ -1698,13 +1650,13 @@ H5B_remove_helper(H5F_t *f, haddr_t addr, const H5B_class_t *type,
 	bt->ndirty = 0;
 	if (level>0) {
 	    if (H5F_addr_defined(bt->left)) {
-		if (NULL==(sibling=H5AC_find(f, H5AC_BT, bt->left, type, udata)))
+		if (NULL==(sibling=H5AC_find_f(f, H5AC_BT, bt->left, type, udata)))
 		    HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, H5B_INS_ERROR, "unable to unlink node from tree");
 		sibling->right = bt->right;
 		sibling->dirty = TRUE;
 	    }
 	    if (H5F_addr_defined(bt->right)) {
-		if (NULL==(sibling=H5AC_find(f, H5AC_BT, bt->right, type, udata)))
+		if (NULL==(sibling=H5AC_find_f(f, H5AC_BT, bt->right, type, udata)))
 		    HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, H5B_INS_ERROR, "unable to unlink node from tree");
 		sibling->left = bt->left;
 		sibling->dirty = TRUE;
@@ -1862,7 +1814,7 @@ H5B_remove(H5F_t *f, const H5B_class_t *type, haddr_t addr, void *udata)
      * If the B-tree is now empty then make sure we mark the root node as
      * being at level zero
      */
-    if (NULL==(bt=H5AC_find(f, H5AC_BT, addr, type, udata)))
+    if (NULL==(bt=H5AC_find_f(f, H5AC_BT, addr, type, udata)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree root node");
     if (0==bt->nchildren && 0!=bt->level) {
 	bt->level = 0;
@@ -1915,20 +1867,20 @@ H5B_nodesize(H5F_t *f, const H5B_class_t *type,
     assert(f);
     assert(type);
     assert(sizeof_rkey > 0);
-    assert(H5B_Kvalue(f, type) > 0);
+    assert(H5F_KVALUE(f, type) > 0);
 
     /*
      * Total native key size.
      */
     if (total_nkey_size)
-	*total_nkey_size = (2 * H5B_Kvalue(f, type) + 1) * type->sizeof_nkey;
+	*total_nkey_size = (2 * H5F_KVALUE(f, type) + 1) * type->sizeof_nkey;
 
     /*
      * Total node size.
      */
     size = (H5B_SIZEOF_HDR(f) + /*node header	*/
-	    2 * H5B_Kvalue(f, type) * H5F_SIZEOF_ADDR(f) +	/*child pointers */
-	    (2 * H5B_Kvalue(f, type) + 1) * sizeof_rkey);	/*keys		*/
+	    2 * H5F_KVALUE(f, type) * H5F_SIZEOF_ADDR(f) +	/*child pointers */
+	    (2 * H5F_KVALUE(f, type) + 1) * sizeof_rkey);	/*keys		*/
 
     /* Set return value */
     ret_value=size;
@@ -1979,19 +1931,19 @@ H5B_copy(H5F_t *f, const H5B_t *old_bt)
     size = H5B_nodesize(f, old_bt->type, &total_native_keysize, old_bt->sizeof_rkey);
 
     /* Allocate memory for the new H5B_t object */
-    if (NULL==(new_node = H5FL_ALLOC(H5B_t,0)))
+    if (NULL==(new_node = H5FL_MALLOC(H5B_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for B-tree root node");
 
     /* Copy the main structure */
     HDmemcpy(new_node,old_bt,sizeof(H5B_t));
 
     /* Compute the number of keys in this node */
-    nkeys=2*H5B_Kvalue(f,old_bt->type);
+    nkeys=2*H5F_KVALUE(f,old_bt->type);
 
-    if (NULL==(new_node->page=H5FL_BLK_ALLOC(page,size,0)) ||
-            NULL==(new_node->native=H5FL_BLK_ALLOC(native_block,total_native_keysize,0)) ||
-            NULL==(new_node->child=H5FL_ARR_ALLOC(haddr_t,nkeys,0)) ||
-            NULL==(new_node->key=H5FL_ARR_ALLOC(H5B_key_t,(nkeys+1),0)))
+    if (NULL==(new_node->page=H5FL_BLK_MALLOC(page,size)) ||
+            NULL==(new_node->native=H5FL_BLK_MALLOC(native_block,total_native_keysize)) ||
+            NULL==(new_node->child=H5FL_ARR_MALLOC(haddr_t,nkeys)) ||
+            NULL==(new_node->key=H5FL_ARR_MALLOC(H5B_key_t,(nkeys+1))))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for B-tree root node");
 
     /* Copy the other structures */
@@ -2064,7 +2016,7 @@ H5B_debug(H5F_t *f, haddr_t addr, FILE *stream, int indent, int fwidth,
     /*
      * Load the tree node.
      */
-    if (NULL == (bt = H5AC_find(f, H5AC_BT, addr, type, udata)))
+    if (NULL == (bt = H5AC_find_f(f, H5AC_BT, addr, type, udata)))
 	HGOTO_ERROR(H5E_BTREE, H5E_CANTLOAD, FAIL, "unable to load B-tree node");
 
     /*
@@ -2101,7 +2053,7 @@ H5B_debug(H5F_t *f, haddr_t addr, FILE *stream, int indent, int fwidth,
     HDfprintf(stream, "%*s%-*s %d (%d)\n", indent, "", fwidth,
 	      "Number of children (max):",
 	      (int) (bt->nchildren),
-	      (int) (2 * H5B_Kvalue(f, type)));
+	      (int) (2 * H5F_KVALUE(f, type)));
 
     /*
      * Print the child addresses
@@ -2164,7 +2116,7 @@ H5B_assert(H5F_t *f, haddr_t addr, const H5B_class_t *type, void *udata)
 	}
     }
     /* Initialize the queue */
-    bt = H5AC_find(f, H5AC_BT, addr, type, udata);
+    bt = H5AC_find_f(f, H5AC_BT, addr, type, udata);
     assert(bt);
     cur = H5MM_calloc(sizeof(struct child_t));
     assert (cur);
diff --git a/src/H5Bprivate.h b/src/H5Bprivate.h
index 3a59d93..d22edcb 100644
--- a/src/H5Bprivate.h
+++ b/src/H5Bprivate.h
@@ -140,6 +140,4 @@ H5_DLL herr_t H5B_remove(H5F_t *f, const H5B_class_t *type, haddr_t addr,
 			  void *udata);
 H5_DLL herr_t H5B_iterate (H5F_t *f, const H5B_class_t *type, H5B_operator_t
                             op, haddr_t addr, void *udata);
-H5_DLL int    H5B_Kvalue(H5F_t *f, const H5B_class_t *type);
-
 #endif
diff --git a/src/H5D.c b/src/H5D.c
index 7485d7e..cab38cd 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -19,6 +19,7 @@
 #include "H5Eprivate.h"		/* Error handling		  	*/
 #include "H5FDprivate.h"	/* File drivers				*/
 #include "H5FLprivate.h"	/* Free Lists                           */
+#include "H5FOprivate.h"        /* File objects                         */
 #include "H5Gprivate.h"		/* Group headers		  	*/
 #include "H5HLprivate.h"	/* Name heap				*/
 #include "H5Iprivate.h"		/* IDs			  		*/
@@ -64,12 +65,25 @@ static int interface_initialize_g = 0;
 
 /* Local functions */
 static herr_t H5D_init_interface(void);
-static herr_t H5D_alloc_storage (H5F_t *f, H5D_t *dset,H5D_time_alloc_t time_alloc);
-static herr_t H5D_init_storage(H5D_t *dataset);
-H5D_t * H5D_new(hid_t dcpl_id);
+static herr_t H5D_alloc_storage (H5F_t *f, H5D_t *dset,H5D_time_alloc_t time_alloc,
+    hbool_t update_time, hbool_t full_overwrite);
+static herr_t H5D_init_storage(H5D_t *dataset, hbool_t full_overwrite);
+static H5D_t * H5D_new(hid_t dcpl_id, hbool_t creating);
+static H5D_t * H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type, 
+           const H5S_t *space, hid_t dcpl_id);
+static H5D_t * H5D_open_oid(H5G_entry_t *ent);
+static herr_t H5D_read(H5D_t *dataset, const H5T_t *mem_type,
+			const H5S_t *mem_space, const H5S_t *file_space,
+			hid_t dset_xfer_plist, void *buf/*out*/);
+static herr_t H5D_write(H5D_t *dataset, const H5T_t *mem_type,
+			 const H5S_t *mem_space, const H5S_t *file_space,
+			 hid_t dset_xfer_plist, const void *buf);
 static herr_t H5D_fill(const void *fill, const H5T_t *fill_type, void *buf,
     const H5T_t *buf_type, const H5S_t *space);
 static herr_t H5D_get_space_status(H5D_t *dset, H5D_space_status_t *allocation);
+static hsize_t H5D_get_storage_size(H5D_t *dset);
+static haddr_t H5D_get_offset(H5D_t *dset);
+static herr_t H5D_set_extent(H5D_t *dataset, const hsize_t *size);
 
 /* Declare a free list to manage the H5D_t struct */
 H5FL_DEFINE_STATIC(H5D_t);
@@ -86,6 +100,9 @@ H5FL_BLK_DEFINE_STATIC(vlen_vl_buf);
 /* Declare a free list to manage other blocks of VL data */
 H5FL_BLK_DEFINE_STATIC(vlen_fl_buf);
 
+/* Define a static "default" dataset structure to use to initialize new datasets */
+static H5D_t H5D_def_dset;
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5D_init
@@ -188,6 +205,7 @@ H5D_init_interface(void)
     H5O_efl_t       efl                      = H5D_CRT_EXT_FILE_LIST_DEF;
     H5O_pline_t     pline                    = H5D_CRT_DATA_PIPELINE_DEF;
 
+    H5P_genplist_t *def_dcpl;               /* Default Dataset Creation Property list */
     size_t          nprops;                 /* Number of properties */
     herr_t          ret_value                = SUCCEED;   /* Return value */
 
@@ -202,7 +220,7 @@ H5D_init_interface(void)
     assert(H5P_CLS_DATASET_XFER_g!=(-1));
 
     /* Get the pointer to the dataset transfer class */
-    if (NULL == (xfer_pclass = H5I_object_verify(H5P_CLS_DATASET_XFER_g, H5I_GENPROP_CLS)))
+    if (NULL == (xfer_pclass = H5I_object(H5P_CLS_DATASET_XFER_g)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list class");
 
     /* Get the number of properties in the class */
@@ -282,7 +300,7 @@ H5D_init_interface(void)
     assert(H5P_CLS_DATASET_CREATE_g != -1);
     
     /* Get the pointer to the dataset creation class */
-    if(NULL == (crt_pclass = H5I_object_verify(H5P_CLS_DATASET_CREATE_g, H5I_GENPROP_CLS)))
+    if(NULL == (crt_pclass = H5I_object(H5P_CLS_DATASET_CREATE_g)))
        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list class");
         
     /* Get the number of properties in the class */
@@ -331,6 +349,37 @@ H5D_init_interface(void)
             HGOTO_ERROR (H5E_PLIST, H5E_CANTREGISTER, FAIL, "can't register default property list");
     } /* end if */
 
+    /* Reset the "default dataset" information */
+    HDmemset(&H5D_def_dset,0,sizeof(H5D_t));
+
+    /* Get the default dataset cretion property list values and initialize the
+     * default dataset with them.
+     */
+    if (NULL == (def_dcpl = H5I_object(H5P_LST_DATASET_CREATE_g)))
+        HGOTO_ERROR(H5E_DATASET, H5E_BADTYPE, NULL, "can't get default dataset creation property list");
+
+    /* Set up the default allocation time information */
+    if(H5P_get(def_dcpl, H5D_CRT_ALLOC_TIME_NAME, &H5D_def_dset.alloc_time) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve space allocation time");
+    if(H5D_def_dset.alloc_time==H5D_ALLOC_TIME_DEFAULT)
+        H5D_def_dset.alloc_time=H5D_ALLOC_TIME_LATE;
+
+    /* Get the default external file list information */
+    if(H5P_get(def_dcpl, H5D_CRT_EXT_FILE_LIST_NAME, &H5D_def_dset.efl) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve external file list");
+
+    /* Get the default data storage method */
+    if(H5P_get(def_dcpl, H5D_CRT_LAYOUT_NAME, &H5D_def_dset.layout.type) < 0)
+         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve layout");
+
+    /* Get the default fill value time */
+    if (H5P_get(def_dcpl, H5D_CRT_FILL_TIME_NAME, &H5D_def_dset.fill_time) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve fill time");
+
+    /* Get the default fill value */
+    if (H5P_get(def_dcpl, H5D_CRT_FILL_VALUE_NAME, &H5D_def_dset.fill) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve fill value");
+
 done:
     FUNC_LEAVE(ret_value);
 }
@@ -404,25 +453,21 @@ H5D_crt_copy(hid_t new_plist_id, hid_t old_plist_id, void UNUSED *copy_data)
     FUNC_ENTER_NOAPI(H5D_crt_copy, FAIL);
 
     /* Verify property list ID */
-    if (NULL == (new_plist = H5P_object_verify(new_plist_id,H5P_DATASET_CREATE)))
+    if (NULL == (new_plist = H5I_object(new_plist_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
-    if (NULL == (old_plist = H5P_object_verify(old_plist_id,H5P_DATASET_CREATE)))
+    if (NULL == (old_plist = H5I_object(old_plist_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
 
     /* Get the fill value, external file list, and data pipeline properties
      * from the old property list */
-    HDmemset(&src_fill,0,sizeof(H5O_fill_t));
     if(H5P_get(old_plist, H5D_CRT_FILL_VALUE_NAME, &src_fill) < 0) 
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get fill value");
-    HDmemset(&src_efl,0,sizeof(H5O_efl_t));
     if(H5P_get(old_plist, H5D_CRT_EXT_FILE_LIST_NAME, &src_efl) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get external file list");
-    HDmemset(&src_pline,0,sizeof(H5O_pline_t));
     if(H5P_get(old_plist, H5D_CRT_DATA_PIPELINE_NAME, &src_pline) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get pipeline");
 
     /* Make copies of fill value, external file list, and data pipeline */
-    HDmemset(&dst_fill,0,sizeof(H5O_fill_t));
     if(src_fill.buf && (NULL==H5O_copy(H5O_FILL, &src_fill, &dst_fill))) {
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't copy fill value");
     }
@@ -433,7 +478,6 @@ H5D_crt_copy(hid_t new_plist_id, hid_t old_plist_id, void UNUSED *copy_data)
     HDmemset(&dst_efl,0,sizeof(H5O_efl_t));
     if(NULL==H5O_copy(H5O_EFL, &src_efl, &dst_efl)) 
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't copy external file list");
-    HDmemset(&dst_pline,0,sizeof(H5O_pline_t));
     if(NULL==H5O_copy(H5O_PLINE, &src_pline, &dst_pline)) 
         HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't copy data pipeline");
 
@@ -481,18 +525,15 @@ H5D_crt_close(hid_t dcpl_id, void UNUSED *close_data)
     FUNC_ENTER_NOAPI(H5D_crt_close, FAIL);
 
     /* Check arguments */
-    if (NULL == (plist = H5P_object_verify(dcpl_id,H5P_DATASET_CREATE)))
+    if (NULL == (plist = H5I_object(dcpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
 
     /* Get the fill value, external file list, and data pipeline properties
      * from the old property list */
-    HDmemset(&fill,0,sizeof(H5O_fill_t));
     if(H5P_get(plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0) 
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get fill value");
-    HDmemset(&efl,0,sizeof(H5O_efl_t));
     if(H5P_get(plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get external file list");
-    HDmemset(&pline,0,sizeof(H5O_pline_t));
     if(H5P_get(plist, H5D_CRT_DATA_PIPELINE_NAME, &pline) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get pipeline");
 
@@ -540,7 +581,7 @@ H5D_xfer_create(hid_t dxpl_id, void UNUSED *create_data)
     FUNC_ENTER_NOAPI(H5D_xfer_create, FAIL);
 
     /* Check arguments */
-    if (NULL == (plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
+    if (NULL == (plist = H5I_object(dxpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list");
 
     /* Get the driver information */
@@ -634,7 +675,7 @@ H5D_xfer_close(hid_t dxpl_id, void UNUSED *close_data)
     FUNC_ENTER_NOAPI(H5D_xfer_close, FAIL);
 
     /* Check arguments */
-    if (NULL == (plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
+    if (NULL == (plist = H5I_object(dxpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list");
 
     if(H5P_get(plist, H5D_XFER_VFL_ID_NAME, &driver_id)<0)
@@ -717,8 +758,9 @@ H5Dcreate(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data space");
     if(H5P_DEFAULT == plist_id)
         plist_id = H5P_DATASET_CREATE_DEFAULT;
-    if(TRUE != H5P_isa_class(plist_id, H5P_DATASET_CREATE))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not dataset create property list");
+    else
+        if(TRUE != H5P_isa_class(plist_id, H5P_DATASET_CREATE))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not dataset create property list");
 
     /* build and open the new dataset */
     if (NULL == (new_dset = H5D_create(loc, name, type, space, plist_id)))
@@ -728,6 +770,10 @@ H5Dcreate(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
     if ((ret_value = H5I_register(H5I_DATASET, new_dset)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTREGISTER, FAIL, "unable to register dataset");
 
+    /* Add the dataset to the list of opened objects in the file */
+    if(H5FO_insert(new_dset->ent.file,new_dset->ent.header,ret_value)<0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTINSERT, FAIL, "can't insert dataset into list of open objects");
+
 done:
     if(ret_value<0) {
         if(new_dset!=NULL)
@@ -762,7 +808,7 @@ hid_t
 H5Dopen(hid_t loc_id, const char *name)
 {
     H5G_entry_t	*loc = NULL;		/*location holding the dataset	*/
-    H5D_t	*dataset = NULL;	/*the dataset			*/
+    H5G_entry_t ent;            	/*dataset symbol table entry	*/
     hid_t	ret_value;
 
     FUNC_ENTER_API(H5Dopen, FAIL);
@@ -774,20 +820,15 @@ H5Dopen(hid_t loc_id, const char *name)
     if (!name || !*name)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no name");
     
-    /* Find the dataset */
-    if (NULL == (dataset = H5D_open(loc, name)))
-	HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, FAIL, "dataset not found");
-    
-    /* Create an atom for the dataset */
-    if ((ret_value = H5I_register(H5I_DATASET, dataset)) < 0)
+    /* Find the dataset object */
+    if (H5G_find(loc, name, NULL, &ent) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, FAIL, "not found");
+
+    /* Open the dataset */
+    if ((ret_value = H5D_open(&ent)) < 0)
 	HGOTO_ERROR(H5E_DATASET, H5E_CANTREGISTER, FAIL, "can't register dataset");
 
 done:
-    if(ret_value<0) {
-        if(dataset!=NULL)
-            H5D_close(dataset);
-    } /* end if */
-
     FUNC_LEAVE(ret_value);
 }
 
@@ -874,7 +915,7 @@ H5Dget_space(hid_t dset_id)
 	HGOTO_ERROR (H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset");
 
     /* Read the data space message and return a data space object */
-    if (NULL==(space=H5D_get_space (dset)))
+    if (NULL==(space=H5S_copy (dset->space)))
 	HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to get data space");
 
     /* Create an atom */
@@ -892,42 +933,6 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5D_get_space
- *
- * Purpose:	Returns the data space associated with the dataset.
- *
- * Return:	Success:	Ptr to a copy of the data space.
- *
- *		Failure:	NULL
- *
- * Programmer:	Robb Matzke
- *              Tuesday, August 25, 1998
- *
- * Modifications:
- *
- *-------------------------------------------------------------------------
- */
-H5S_t *
-H5D_get_space(H5D_t *dset)
-{
-    H5S_t	*space;
-    H5S_t	*ret_value;     /* Return value */
-    
-    FUNC_ENTER_NOAPI(H5D_get_space, NULL);
-    assert(dset);
-
-    if (NULL==(space=H5S_read(&(dset->ent))))
-	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to load space info from dataset header");
-
-    /* Set return value */
-    ret_value=space;
-
-done:
-    FUNC_LEAVE(ret_value);
-}
-
-
-/*-------------------------------------------------------------------------
  * Function:	H5Dget_space_status
  *
  * Purpose:	Returns the status of data space allocation.
@@ -981,7 +986,7 @@ done:
  */
 static herr_t H5D_get_space_status(H5D_t *dset, H5D_space_status_t *allocation)
 {
-    H5S_t      *space=NULL;         /* Dataset's dataspace */
+    H5S_t      *space;              /* Dataset's dataspace */
     hsize_t     space_allocated;    /* The number of bytes allocated for chunks */
     hssize_t    total_elem;         /* The total number of elements in dataspace */
     size_t      type_size;          /* The size of the datatype for the dataset */
@@ -990,9 +995,11 @@ static herr_t H5D_get_space_status(H5D_t *dset, H5D_space_status_t *allocation)
 
     FUNC_ENTER_NOINIT(H5D_get_space_status);
 
+    assert(dset);
+
     /* Get the dataset's dataspace */
-    if((space=H5D_get_space(dset))==NULL)
-	HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to get dataspace");
+    space=dset->space;
+    assert(space);
 
     /* Get the total number of elements in dataset's dataspace */
     if((total_elem=H5S_get_simple_extent_npoints(space))<0)
@@ -1022,8 +1029,6 @@ static herr_t H5D_get_space_status(H5D_t *dset, H5D_space_status_t *allocation)
     } /* end else */
 
 done:
-    if(space)
-	H5S_close(space);
     FUNC_LEAVE(ret_value);
 }
 
@@ -1247,9 +1252,9 @@ H5Dread(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
     /* Get the default dataset transfer property list if the user didn't provide one */
     if (H5P_DEFAULT == plist_id)
         plist_id= H5P_DATASET_XFER_DEFAULT;
-
-    if (TRUE!=H5P_isa_class(plist_id,H5P_DATASET_XFER))
-	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
+    else
+        if (TRUE!=H5P_isa_class(plist_id,H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
     if (!buf)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no output buffer");
 
@@ -1338,9 +1343,9 @@ H5Dwrite(hid_t dset_id, hid_t mem_type_id, hid_t mem_space_id,
     /* Get the default dataset transfer property list if the user didn't provide one */
     if (H5P_DEFAULT == plist_id)
         plist_id= H5P_DATASET_XFER_DEFAULT;
-
-    if (TRUE!=H5P_isa_class(plist_id,H5P_DATASET_XFER))
-	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
+    else
+        if (TRUE!=H5P_isa_class(plist_id,H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
     if (!buf)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no output buffer");
 
@@ -1416,8 +1421,8 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-H5D_t *
-H5D_new(hid_t dcpl_id)
+static H5D_t *
+H5D_new(hid_t dcpl_id, hbool_t creating)
 {
     H5P_genplist_t	*plist;    /* Property list created */
     H5D_t	*new_dset = NULL;  /* New dataset object */
@@ -1425,16 +1430,31 @@ H5D_new(hid_t dcpl_id)
     
     FUNC_ENTER_NOAPI(H5D_new, NULL);
 
-    if (NULL==(new_dset = H5FL_ALLOC(H5D_t,1)))
+    if (NULL==(new_dset = H5FL_MALLOC(H5D_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-    if(H5P_DEFAULT == dcpl_id)
-        dcpl_id = H5P_DATASET_CREATE_DEFAULT;
 
-    /* Get the property list */
-    if (NULL == (plist = H5P_object_verify(dcpl_id,H5P_DATASET_CREATE)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a property list");
+    /* If we are using the default dataset creation property list, during creation
+     * don't bother to copy it, just increment the reference count
+     */
+    if(creating && dcpl_id == H5P_DATASET_CREATE_DEFAULT) {
+        /* Copy the default dataset information */
+        HDmemcpy(new_dset,&H5D_def_dset,sizeof(H5D_t));
+
+        if(H5I_inc_ref(dcpl_id)<0)
+            HGOTO_ERROR (H5E_DATASET, H5E_CANTINC, NULL, "Can't increment default DCPL ID");
+        new_dset->dcpl_id = dcpl_id;
+    } /* end if */
+    else {
+        /* Reset the dataset information */
+        HDmemset(new_dset,0,sizeof(H5D_t));
+
+        /* Get the property list */
+        if (NULL == (plist = H5I_object(dcpl_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a property list");
+
+        new_dset->dcpl_id = H5P_copy_plist(plist);
+    } /* end else */
 
-    new_dset->dcpl_id = H5P_copy_plist(plist);
     new_dset->ent.header = HADDR_UNDEF;
 
     /* Set return value */
@@ -1442,8 +1462,11 @@ H5D_new(hid_t dcpl_id)
 
 done:
     if(ret_value==NULL) {
-        if(new_dset!=NULL)
+        if(new_dset!=NULL) {
+            if(new_dset->dcpl_id!=0)
+                H5I_dec_ref(new_dset->dcpl_id);
             H5FL_FREE(H5D_t,new_dset);
+        } /* end if */
     } /* end if */
 
     FUNC_LEAVE(ret_value);
@@ -1451,7 +1474,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5D_update_entry_cache
+ * Function:	H5D_update_entry_info
  *
  * Purpose:	Create and fill an H5G_entry_t object for insertion into
  *              the group LOC.
@@ -1471,72 +1494,86 @@ done:
  *	
  *-------------------------------------------------------------------------
  */
-herr_t
-H5D_update_entry_cache(H5F_t *file, H5G_entry_t *ent, H5G_entry_t *loc,
-                       const char *name, const H5S_t *space,
-                       H5P_genplist_t *plist, H5O_layout_t *layout, H5T_t *type,
-                       hbool_t allocate_header, haddr_t header)
+static herr_t
+H5D_update_entry_info(H5F_t *file, H5D_t *dset, H5P_genplist_t *plist)
 {
-    H5O_pline_t         dcpl_pline;
-    H5D_alloc_time_t    alloc_time;
     size_t              ohdr_size = H5D_MINHDR_SIZE;    /* Size of dataset's object header */
+    H5G_entry_t        *ent=NULL;    /* Dataset's group entry */
+    H5O_layout_t       *layout; /* Dataset's layout information */
+    H5T_t              *type;   /* Dataset's datatype */
+    H5S_t              *space;  /* Dataset's dataspace */
+    H5D_alloc_time_t alloc_time;/* Dataset's allocation time */
+    H5O_efl_t          *efl;    /* Dataset's external file list */
 
     /* fill value variables */
     H5D_fill_time_t	fill_time;
-    H5O_fill_t		fill_prop = { NULL, 0, NULL };
+    H5O_fill_t		*fill_prop;     /* Pointer to dataset's fill value information */
     H5O_fill_new_t      fill = { NULL, 0, NULL, H5D_ALLOC_TIME_LATE, H5D_FILL_TIME_ALLOC, TRUE };
     H5D_fill_value_t	fill_status;
 
+    H5O_t              *oh=NULL;        /* Pointer to dataset's object header */
+
     /* return code */
     herr_t ret_value = SUCCEED;
 
-    FUNC_ENTER_NOAPI(H5D_update_entry_cache, FAIL);
+    FUNC_ENTER_NOAPI(H5D_update_entry_info, FAIL);
+
+    /* Sanity checking */
+    assert(file);
+    assert(dset);
 
+    /* Pick up former parameters */
+    ent=&dset->ent;
+    layout=&dset->layout;
+    type=dset->type;
+    space=dset->space;
+    alloc_time=dset->alloc_time;
+    efl=&dset->efl;
+
+    /* Add the dataset's raw data size to the size of the header, if the raw data will be stored as compact */
     if (layout->type == H5D_COMPACT)
         ohdr_size += layout->size;
 
-    /* If TRUE, then allocate the space in the file for the header */
-    if (allocate_header) {
-        /* Create (open for write access) an object header */
-        if (H5O_create(file, ohdr_size, ent) < 0)
-            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
-                        "unable to create dataset object header");
-    } else {
-        /*
-         * Just initialize the header to the specified address and open
-         * it for us
-         */
-        HDmemset(ent, 0, sizeof(H5G_entry_t));
+    /* Create (open for write access) an object header */
+    if (H5O_create(file, ohdr_size, ent) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create dataset object header");
 
-        if (H5O_init(file, ohdr_size, ent, header) < 0)
-            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
-                        "unable to initialize dataset object header");
-    }
+    /* Get a pointer to the object header itself */
+    if((oh=H5O_protect(ent))==NULL)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to protect dataset object header");
 
-    /*
-     * Retrieve properties of fill value and others. Copy them into new fill
-     * value struct. Convert the fill value to the dataset type and write 
-     * the message
-     */
-    if (H5P_get(plist, H5D_CRT_ALLOC_TIME_NAME, &alloc_time) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve space allocation time");
+    /* Point at dataset's copy, to cache it for later */
+    fill_prop=&dset->fill;
+    fill_time=dset->fill_time;
 
-    if (H5P_get(plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve fill time");
+    /* Check if dataset has non-default creation property list */
+    if(dset->dcpl_id!=H5P_DATASET_CREATE_DEFAULT) {
+        /*
+         * Retrieve properties of fill value and others. Copy them into new fill
+         * value struct. Convert the fill value to the dataset type and write 
+         * the message
+         */
+        if (H5P_get(plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve fill time");
+        dset->fill_time=fill_time;    /* Cache this for later */
 
-    if (H5P_fill_value_defined(plist, &fill_status) < 0)
+        if(fill_time==H5D_FILL_TIME_NEVER && H5T_detect_class(type, H5T_VLEN))
+            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, FAIL, "Dataset doesn't support VL datatype when fill value is not defined");
+     
+        /* Get the fill value information from the property list */
+        if (H5P_get(plist, H5D_CRT_FILL_VALUE_NAME, fill_prop) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve fill value");
+    } /* end if */
+
+    if (H5P_is_fill_value_defined(fill_prop, &fill_status) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't tell if fill value defined");
 
     if (fill_status == H5D_FILL_VALUE_DEFAULT || fill_status == H5D_FILL_VALUE_USER_DEFINED) {
-	if (H5P_get(plist, H5D_CRT_FILL_VALUE_NAME, &fill_prop) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve fill value");
-
-        if (H5O_copy(H5O_FILL, &fill_prop, &fill) == NULL)
+        if (H5O_copy(H5O_FILL, fill_prop, &fill) == NULL)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT,FAIL, "unable to copy fill value");
 
-        if (fill_prop.buf && fill_prop.size > 0 && H5O_fill_convert(&fill, type) < 0)
-            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
-                        "unable to convert fill value to dataset type");
+        if (fill_prop->buf && fill_prop->size > 0 && H5O_fill_convert(&fill, type) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to convert fill value to dataset type");
 
 	fill.fill_defined = TRUE;
     } else if (fill_status == H5D_FILL_VALUE_UNDEFINED) {
@@ -1544,8 +1581,7 @@ H5D_update_entry_cache(H5F_t *file, H5G_entry_t *ent, H5G_entry_t *loc,
  	fill.type = fill.buf = NULL;
  	fill.fill_defined = FALSE;
     } else {
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL,
-                    "unable to determine if fill value is defined");
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "unable to determine if fill value is defined");
     }
 
     fill.alloc_time = alloc_time;
@@ -1555,79 +1591,51 @@ H5D_update_entry_cache(H5F_t *file, H5G_entry_t *ent, H5G_entry_t *loc,
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT,FAIL, "unable to create dataset");
 
     /* Write new fill value message */
-    if (H5O_modify(ent, H5O_FILL_NEW, 0, H5O_FLAG_CONSTANT, &fill) < 0)
+    if (H5O_append(file, oh, H5O_FILL_NEW, H5O_FLAG_CONSTANT, &fill) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update fill value header message");        
-    H5O_reset(H5O_FILL, &fill_prop);
 
-    if (fill.buf && H5O_copy(H5O_FILL, &fill, &fill_prop) == NULL)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT,FAIL,"unable to copy fill value");
+    /* If there is valid information for the old fill value struct, update it */
+    if (fill.buf) {
+        /* Clear any previous values */
+        H5O_reset(H5O_FILL, fill_prop);
 
-    H5O_reset(H5O_FILL_NEW, &fill);
+        /* Copy new fill value information to old fill value struct */
+        if(H5O_copy(H5O_FILL, &fill, fill_prop) == NULL)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT,FAIL,"unable to copy fill value");
 
-    /* Write old fill value */
-    if (fill_prop.buf && H5O_modify(ent, H5O_FILL, 0, H5O_FLAG_CONSTANT, &fill_prop) < 0)        
-	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
-                    "unable to update fill value header message");
+        /* Write old fill value */
+        if (fill_prop->buf && H5O_append(file, oh, H5O_FILL, H5O_FLAG_CONSTANT, fill_prop) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update fill value header message");
 
-    if (H5P_set(plist, H5D_CRT_FILL_VALUE_NAME, &fill_prop) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set fill value");  
+        /* Update dataset creation property */
+        if (H5P_set(plist, H5D_CRT_FILL_VALUE_NAME, fill_prop) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, FAIL, "can't set fill value");  
+    } /* end if */
 
     /* Update the type and space header messages */
-    if (H5O_modify(ent, H5O_DTYPE, 0, H5O_FLAG_CONSTANT | H5O_FLAG_SHARED, type) < 0 ||
-            H5S_modify(ent, space) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
-                    "unable to update type or space header messages");
+    if (H5O_append(file, oh, H5O_DTYPE, H5O_FLAG_CONSTANT | H5O_FLAG_SHARED, type) < 0 ||
+            H5S_append(file, oh, space) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update type or space header messages");
 
-    /* Update the filters message */
-    if (H5P_get(plist, H5D_CRT_DATA_PIPELINE_NAME, &dcpl_pline) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve pipeline filter");
-
-    if (dcpl_pline.nfilters > 0 &&
-            H5O_modify(ent, H5O_PLINE, 0, H5O_FLAG_CONSTANT, &dcpl_pline) < 0)
-        HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update filter header message");
-
-    /* Add a modification time message. */
-    if (H5O_touch(ent, TRUE) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
-                    "unable to update modification time message");
-    
-    /* Give the dataset a name */
-    if (H5G_insert(loc, name, ent) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to name dataset");
+    /* Update the filters message, if this is a chunked dataset */
+    if(layout->type==H5D_CHUNKED) {
+        H5O_pline_t         pline;      /* Chunked data I/O pipeline info */
 
-done:
-    FUNC_LEAVE(ret_value);
-}
+        if (H5P_get(plist, H5D_CRT_DATA_PIPELINE_NAME, &pline) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "Can't retrieve pipeline filter");
 
-
-/*-------------------------------------------------------------------------
- * Function:	H5D_update_external_storage_cache
- *
- * Purpose:	Update the external cache if the dataset uses external
- *              files.
- *
- *              This code was originally found at the end of H5D_create()
- *              but was placed here for general use.
- *
- * Return:	Success:    SUCCEED
- *		Failure:    FAIL
- *
- * Errors:
- *
- * Programmer:	Bill Wendling
- *		Thursday, October 31, 2002
- *
- * Modifications:
- *	
- *-------------------------------------------------------------------------
- */
-herr_t
-H5D_update_external_storage_cache(H5F_t *file, H5G_entry_t *ent,
-                                  H5O_efl_t *efl, H5O_layout_t *layout)
-{
-    herr_t ret_value = SUCCEED;
+        if (pline.nfilters > 0 &&
+                H5O_append(file, oh, H5O_PLINE, H5O_FLAG_CONSTANT, &pline) < 0)
+            HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update filter header message");
+    } /* end if */
 
-    FUNC_ENTER_NOAPI(H5D_update_external_storage_cache, FAIL);
+    /*
+     * Allocate storage if space allocate time is early; otherwise delay
+     * allocation until later.
+     */
+    if (alloc_time == H5D_ALLOC_TIME_EARLY)
+        if (H5D_alloc_storage(file, dset, H5D_ALLOC_CREATE, FALSE, FALSE) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize storage"); 
 
     /* Update external storage message */
     if (efl->nused > 0) {
@@ -1639,13 +1647,11 @@ H5D_update_external_storage_cache(H5F_t *file, H5G_entry_t *ent,
 
         if (H5HL_create(file, heap_size, &efl->heap_addr/*out*/) < 0 ||
                 H5HL_insert(file, efl->heap_addr, 1, "") == (size_t)(-1))
-            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
-                        "unable to create external file list name heap");
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create external file list name heap");
 
         for (i = 0; i < efl->nused; ++i) {
             size_t offset = H5HL_insert(file, efl->heap_addr,
-                                        HDstrlen(efl->slot[i].name) + 1,
-                                        efl->slot[i].name);
+                        HDstrlen(efl->slot[i].name) + 1, efl->slot[i].name);
 
             assert(0 == efl->slot[i].name_offset);
 
@@ -1655,16 +1661,26 @@ H5D_update_external_storage_cache(H5F_t *file, H5G_entry_t *ent,
             efl->slot[i].name_offset = offset;
         }
 
-        if (H5O_modify(ent, H5O_EFL, 0, H5O_FLAG_CONSTANT, efl) < 0)
-            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL,
-                        "unable to update external file list message");
+        if (H5O_append(file, oh, H5O_EFL, H5O_FLAG_CONSTANT, efl) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update external file list message");
     }
 
     /* Update layout message */
-    if (H5D_COMPACT != layout->type && H5O_modify(ent, H5O_LAYOUT, 0, 0, layout) < 0)
+    /* (Don't make layout message constant yet, since space may not be allocated) */
+    /* Note: this is relying on H5D_alloc_storage not calling H5O_modify during dataset creation */
+    if (H5D_COMPACT != layout->type && H5O_append(file, oh, H5O_LAYOUT, 0, layout) < 0)
          HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update layout"); 
 
+    /* Add a modification time message. */
+    if (H5O_touch_oh(file, oh, TRUE) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update modification time message");
+
 done:
+    /* Release pointer to object header itself */
+    if(ent!=NULL && oh!=NULL)
+        if(H5O_unprotect(ent,oh)<0)
+            HDONE_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to unprotect dataset object header");
+
     FUNC_LEAVE(ret_value);
 }
 
@@ -1726,7 +1742,7 @@ done:
  *	
  *-------------------------------------------------------------------------
  */
-H5D_t *
+static H5D_t *
 H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type, 
            const H5S_t *space, hid_t dcpl_id)
 {
@@ -1736,16 +1752,10 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
     hsize_t 		comp_data_size;
     unsigned		u;
     hsize_t		max_dim[H5O_LAYOUT_NDIMS]={0};
-    H5O_efl_t           efl;
-    H5F_t		*f = NULL;
-    H5O_pline_t         dcpl_pline;
-    H5D_layout_t        dcpl_layout;
+    H5F_t		*file;
     int                 chunk_ndims = 0;
     hsize_t             chunk_size[32]={0};
-    H5D_alloc_time_t    alloc_time;
-    H5D_fill_time_t	fill_time;
-    H5P_genplist_t 	*plist;      /* Property list */
-    H5P_genplist_t 	*new_plist;  /* New Property list */
+    H5P_genplist_t 	*new_plist=NULL;  /* New Property list */
 
     FUNC_ENTER_NOAPI(H5D_create, NULL);
 
@@ -1755,97 +1765,105 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
     assert (type);
     assert (space);
 
-    /* Get property list object */
-    if (NULL == (plist = H5P_object_verify(dcpl_id,H5P_DATASET_CREATE)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "can't get dataset creation property list");
-
-    if(H5P_get(plist, H5D_CRT_DATA_PIPELINE_NAME, &dcpl_pline) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve pipeline filter");
-    if(H5P_get(plist, H5D_CRT_LAYOUT_NAME, &dcpl_layout) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve layout");
-    if(dcpl_pline.nfilters > 0 && H5D_CHUNKED != dcpl_layout)
-        HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, NULL, "filters can only be used with chunked layout");
-    if(H5P_get(plist, H5D_CRT_ALLOC_TIME_NAME, &alloc_time) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve space allocation time");
-
-    /* Check if the alloc_time is the default and set it accordingly */
-    if(alloc_time==H5D_ALLOC_TIME_DEFAULT) {
-        switch(dcpl_layout) {
-            case H5D_COMPACT:
-                alloc_time=H5D_ALLOC_TIME_EARLY;
-                break;
-
-            case H5D_CONTIGUOUS:
-                alloc_time=H5D_ALLOC_TIME_LATE;
-                break;
-
-            case H5D_CHUNKED:
-                alloc_time=H5D_ALLOC_TIME_INCR;
-                break;
-
-            default:
-                HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, NULL, "not implemented yet");
-        } /* end switch */
-    } /* end if */
-
-    /* Don't allow compact datasets to allocate space later */
-    if(dcpl_layout==H5D_COMPACT && alloc_time!=H5D_ALLOC_TIME_EARLY)
-        HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, NULL, "compact dataset doesn't support late space allocation");
-
-    /* What file is the dataset being added to? */
-    if (NULL==(f=H5G_insertion_file(loc, name)))
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to locate insertion point");
-
-    /* If MPIO or MPIPOSIX is used, no filter support yet. */
-    if((IS_H5FD_MPIO(f) || IS_H5FD_MPIPOSIX(f)) && dcpl_pline.nfilters > 0) 
-        HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, NULL, "Parallel I/O does not support filters yet");
-
-    /* Check if this dataset is going into a parallel file and set space allocation time */
-    if(IS_H5FD_MPIO(f) || IS_H5FD_MPIPOSIX(f))
-        alloc_time=H5D_ALLOC_TIME_EARLY;
-   
-    if(H5P_get(plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve fill time");
-
-    if(fill_time==H5D_FILL_TIME_NEVER && H5T_detect_class(type, H5T_VLEN))
-        HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, NULL, "Dataset doesn't support VL datatype when fill value is not defined");
- 
-    /* Initialize the dataset object */
-    if(NULL == (new_dset = H5D_new(dcpl_id)))
-        HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-
     /* Check if the datatype is "sensible" for use in a dataset */
     if(H5T_is_sensible(type)!=TRUE)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "datatype is not sensible");
 
+    /* Initialize the dataset object */
+    if(NULL == (new_dset = H5D_new(dcpl_id,TRUE)))
+        HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+
     /* Copy datatype for dataset */
     if((new_dset->type = H5T_copy(type, H5T_COPY_ALL))==NULL)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTCOPY, NULL, "can't copy datatype");
 
+    /* What file is the dataset being added to? */
+    if (NULL==(file=H5G_insertion_file(loc, name)))
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to locate insertion point");
+
     /* Mark any VL datatypes as being on disk now */
-    if (H5T_vlen_mark(new_dset->type, f, H5T_VLEN_DISK)<0)
+    if (H5T_vlen_mark(new_dset->type, file, H5T_VLEN_DISK)<0)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "invalid VL location");
 
-    /* Get new dataset's property list object */
-    if (NULL == (new_plist = H5I_object(new_dset->dcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "can't get dataset creation property list");
+    /* Copy dataspace for dataset */
+    if((new_dset->space = H5S_copy(space))==NULL)
+        HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, NULL, "can't copy dataspace");
+
+    /* Set the dataset's dataspace to 'all' selection */
+    if(H5S_select_all(new_dset->space,1)<0)
+        HGOTO_ERROR (H5E_DATASPACE, H5E_CANTSET, NULL, "unable to set all selection");
+
+    /* Check if the dataset has a non-default DCPL & get important values, if so */
+    if(new_dset->dcpl_id!=H5P_DATASET_CREATE_DEFAULT) {
+        H5D_layout_t    dcpl_layout;    /* Dataset's layout information */
+        H5O_pline_t     dcpl_pline;     /* Dataset's I/O pipeline information */
+        H5D_alloc_time_t alloc_time;    /* Dataset's allocation time */
+
+        /* Get new dataset's property list object */
+        if (NULL == (new_plist = H5I_object(new_dset->dcpl_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "can't get dataset creation property list");
+
+        if(H5P_get(new_plist, H5D_CRT_DATA_PIPELINE_NAME, &dcpl_pline) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve pipeline filter");
+        if(H5P_get(new_plist, H5D_CRT_LAYOUT_NAME, &dcpl_layout) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve layout");
+        if(dcpl_pline.nfilters > 0 && H5D_CHUNKED != dcpl_layout)
+            HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, NULL, "filters can only be used with chunked layout");
+        if(H5P_get(new_plist, H5D_CRT_ALLOC_TIME_NAME, &alloc_time) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve space allocation time");
+
+        /* Check if the alloc_time is the default and set it accordingly */
+        if(alloc_time==H5D_ALLOC_TIME_DEFAULT) {
+            switch(dcpl_layout) {
+                case H5D_COMPACT:
+                    alloc_time=H5D_ALLOC_TIME_EARLY;
+                    break;
+
+                case H5D_CONTIGUOUS:
+                    alloc_time=H5D_ALLOC_TIME_LATE;
+                    break;
+
+                case H5D_CHUNKED:
+                    alloc_time=H5D_ALLOC_TIME_INCR;
+                    break;
+
+                default:
+                    HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, NULL, "not implemented yet");
+            } /* end switch */
+        } /* end if */
 
-    /* Set the alloc_time for the dataset, in case the default was used */
-    if(H5P_set(new_plist, H5D_CRT_ALLOC_TIME_NAME, &alloc_time) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "can't set allocation time");  
+        /* Don't allow compact datasets to allocate space later */
+        if(dcpl_layout==H5D_COMPACT && alloc_time!=H5D_ALLOC_TIME_EARLY)
+            HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, NULL, "compact dataset doesn't support late space allocation");
 
-    if(H5P_get(new_plist, H5D_CRT_CHUNK_DIM_NAME, &chunk_ndims) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve layout");
+        /* Set the alloc_time for the dataset, in case the default was used */
+        new_dset->alloc_time=alloc_time;
+
+        /* If MPIO or MPIPOSIX is used, no filter support yet. */
+        if((IS_H5FD_MPIO(file) || IS_H5FD_MPIPOSIX(file)) && dcpl_pline.nfilters > 0) 
+            HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, NULL, "Parallel I/O does not support filters yet");
+
+        /* Chunked datasets are non-default, so retrieve their info here */
+        if(H5P_get(new_plist, H5D_CRT_CHUNK_DIM_NAME, &chunk_ndims) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve layout");
     
-    if(H5P_get(new_plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve external file list");
+        /* Get the dataset's external file list information */
+        if(H5P_get(new_plist, H5D_CRT_EXT_FILE_LIST_NAME, &new_dset->efl) < 0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve external file list");
 
-    /* Total raw data size */
-    if(H5P_get(new_plist, H5D_CRT_LAYOUT_NAME, &(new_dset->layout.type)) < 0)
-         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve layout");
-    new_dset->layout.ndims = H5S_get_simple_extent_ndims(space) + 1;
+        /* Get the dataset's data storage method */
+        if(H5P_get(new_plist, H5D_CRT_LAYOUT_NAME, &(new_dset->layout.type)) < 0)
+             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve layout");
+    } /* end if */
+
+    /* Check if this dataset is going into a parallel file and set space allocation time */
+    if(IS_H5FD_MPIO(file) || IS_H5FD_MPIPOSIX(file))
+        new_dset->alloc_time=H5D_ALLOC_TIME_EARLY;
+   
+    /* Set up layout information */
+    new_dset->layout.ndims = H5S_get_simple_extent_ndims(new_dset->space) + 1;
     assert((unsigned)(new_dset->layout.ndims) <= NELMTS(new_dset->layout.dim));
-    new_dset->layout.dim[new_dset->layout.ndims-1] = H5T_get_size(new_dset->type);    
+    new_dset->layout.dim[new_dset->layout.ndims-1] = H5T_get_size(new_dset->type);
     new_dset->layout.addr = HADDR_UNDEF;        /* Initialize to no address */
 
     switch (new_dset->layout.type) {
@@ -1855,15 +1873,15 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
              * Also, only the slowest varying dimension of a simple data space
              * can be extendible.
              */
-	    if ((ndims=H5S_get_simple_extent_dims(space, new_dset->layout.dim, max_dim))<0)
+	    if ((ndims=H5S_get_simple_extent_dims(new_dset->space, new_dset->layout.dim, max_dim))<0)
                 HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to initialize contiguous storage");
             for (i=1; i<ndims; i++) {
                 if (max_dim[i]>new_dset->layout.dim[i])
                     HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, NULL, "only the first dimension can be extendible");
             }
-            if (efl.nused>0) {
-                hsize_t max_points = H5S_get_npoints_max (space);
-                hsize_t max_storage = H5O_efl_total_size (&efl);
+            if (new_dset->efl.nused>0) {
+                hsize_t max_points = H5S_get_npoints_max (new_dset->space);
+                hsize_t max_storage = H5O_efl_total_size (&new_dset->efl);
 
                 if (H5S_UNLIMITED==max_points) {
                     if (H5O_EFL_UNLIMITED!=max_storage)
@@ -1883,9 +1901,9 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
              * Chunked storage allows any type of data space extension, so we
              * don't even bother checking.
              */
-            if(chunk_ndims != H5S_get_simple_extent_ndims(space))
+            if(chunk_ndims != H5S_get_simple_extent_ndims(new_dset->space))
                 HGOTO_ERROR(H5E_DATASET, H5E_BADVALUE, NULL, "dimensionality of chunks doesn't match the data space");
-            if (efl.nused>0)
+            if (new_dset->efl.nused>0)
                 HGOTO_ERROR (H5E_DATASET, H5E_BADVALUE, NULL, "external storage not supported with chunked layout");
 
             /*
@@ -1895,7 +1913,7 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
             if(H5P_get(new_plist, H5D_CRT_CHUNK_SIZE_NAME, chunk_size) < 0)
                 HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve chunk size");
 
-            if (H5S_get_simple_extent_dims(space, NULL, max_dim)<0)
+            if (H5S_get_simple_extent_dims(new_dset->space, NULL, max_dim)<0)
                 HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to query maximum dimensions");
             for (u=0; u<new_dset->layout.ndims-1; u++) {
 	        if(max_dim[u] != H5S_UNLIMITED && max_dim[u] < chunk_size[u])
@@ -1917,7 +1935,7 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
 	    /* Verify data size is smaller than maximum header message size
 	     * (64KB) minus other layout message fields.
 	     */
-            comp_data_size=H5O_MAX_SIZE-H5O_layout_meta_size(f, &(new_dset->layout));
+            comp_data_size=H5O_MAX_SIZE-H5O_layout_meta_size(file, &(new_dset->layout));
             if(new_dset->layout.size > comp_data_size)
                 HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "compact dataset size is bigger than header message maximum size");
             if ((ndims=H5S_get_simple_extent_dims(space, new_dset->layout.dim, max_dim))<0) 
@@ -1931,38 +1949,32 @@ H5D_create(H5G_entry_t *loc, const char *name, const H5T_t *type,
     } /* end switch */
 
     /*
-     * Update the entry cache. That is, create and add a new
-     * "H5G_entry_t" object to the group this dataset is being initially
-     * created in.
+     * Update the dataset's entry info.
      */
-    if (H5D_update_entry_cache(f, &new_dset->ent, loc, name, space, new_plist,
-                               &new_dset->layout, new_dset->type, TRUE, (haddr_t)0) != SUCCEED)
+    if (H5D_update_entry_info(file, new_dset, new_plist) != SUCCEED)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "can't update the metadata cache");
 
-    /*
-     * Allocate storage if space allocate time is early; otherwise delay
-     * allocation until later.
+    /* 
+     * Give the dataset a name.  That is, create and add a new
+     * "H5G_entry_t" object to the group this dataset is being initially
+     * created in.
      */
-    if (H5P_get(new_plist, H5D_CRT_ALLOC_TIME_NAME, &alloc_time) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't retrieve space allocation time");
-
-    if (alloc_time == H5D_ALLOC_TIME_EARLY)
-        if (H5D_alloc_storage(f, new_dset, H5D_ALLOC_CREATE) < 0)
-            HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to initialize storage"); 
-
-    /* Update the external storage cache if this is an external object */
-    if (H5D_update_external_storage_cache(f, &new_dset->ent, &efl, &new_dset->layout) != SUCCEED)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "can't update the external metadata cache");
+    if (H5G_insert(loc, name, &new_dset->ent) < 0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to name dataset");
 
     /* Success */
     ret_value = new_dset;
 
 done:
     if (!ret_value && new_dset) {
+        if (new_dset->space)
+            H5S_close(new_dset->space);
         if (new_dset->type)
             H5T_close(new_dset->type);
         if (H5F_addr_defined(new_dset->ent.header))
             H5O_close(&(new_dset->ent));
+        if(new_dset->dcpl_id!=0)
+            H5I_dec_ref(new_dset->dcpl_id);
         new_dset->ent.file = NULL;
         H5FL_FREE(H5D_t,new_dset);
     }
@@ -2024,53 +2036,59 @@ done:
  *------------------------------------------------------------------------- 
  * Function:	H5D_open
  *
- * Purpose:	Finds a dataset named NAME in file F and builds a descriptor
- *		for it, opening it for access.
- *
- * Return:	Success:	Pointer to a new dataset descriptor.
+ * Purpose:	Checks if dataset is already open, or opens a dataset for
+ *              access.
  *
- *		Failure:	NULL
+ * Return:	Success:	Dataset ID
+ *		Failure:	FAIL
  *
  * Errors:
  *
- * Programmer:	Robb Matzke
- *		Thursday, December  4, 1997
+ * Programmer:	Quincey Koziol
+ *		Friday, December 20, 2002
  *
  * Modifications:
- * 	Robb Matzke, 9 Jun 1998
- *	The data space message is no longer cached in the dataset struct.
- *	
- *  	Quincey Koziol, 12 Oct 1998
- *  	Moved guts of function into H5D_open_oid
- *
- *      Pedro Vicente, <pvn@ncsa.uiuc.edu> 18 Sep 2002
- *      Added `id to name' support.
  *
  *-------------------------------------------------------------------------
  */
-H5D_t *
-H5D_open(H5G_entry_t *loc, const char *name)
+hid_t
+H5D_open(H5G_entry_t *ent)
 {
-    H5D_t	*dataset = NULL;	/*the dataset which was found	*/
-    H5D_t	*ret_value = NULL;	/*return value			*/
-    H5G_entry_t ent;            	/*dataset symbol table entry	*/
+    hid_t	ret_value;              /* Return value */
     
     FUNC_ENTER_NOAPI(H5D_open, NULL);
 
     /* check args */
-    assert (loc);
-    assert (name && *name);
+    assert (ent);
     
-    /* Find the dataset object */
-    if (H5G_find(loc, name, NULL, &ent) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, NULL, "not found");
+    /* Check if dataset was already open */
+    if((ret_value=H5FO_opened(ent->file,ent->header))<0) {
+        H5D_t	*dataset;	/*the dataset which was found	*/
 
-    /* Open the dataset object */
-    if ((dataset=H5D_open_oid(&ent)) ==NULL)
-        HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, NULL, "not found");
+        H5E_clear();
 
-    /* Success */
-    ret_value = dataset;
+        /* Open the dataset object */
+        if ((dataset=H5D_open_oid(ent)) ==NULL)
+            HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, FAIL, "not found");
+
+        /* Create an atom for the dataset */
+        if ((ret_value = H5I_register(H5I_DATASET, dataset)) < 0) {
+            H5D_close(dataset);
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTREGISTER, FAIL, "can't register dataset");
+        } /* end if */
+
+        /* Add the dataset to the list of opened objects in the file */
+        if(H5FO_insert(ent->file,ent->header,ret_value)<0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINSERT, FAIL, "can't insert dataset into list of open objects");
+    } /* end if */
+    else {
+        /* Dataset is already open, increment the reference count on the ID */
+        if(H5I_inc_ref(ret_value)<0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTINC, FAIL, "Can't increment dataset ID");
+
+        /* Release the dataset entry we located earlier */
+        H5G_free_ent_name(ent);
+    } /* end else */
 
 done:
     FUNC_LEAVE(ret_value);
@@ -2104,15 +2122,14 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-H5D_t *
+static H5D_t *
 H5D_open_oid(H5G_entry_t *ent)
 {
     H5D_t 	*dataset = NULL;	/*new dataset struct 		*/
     H5D_t 	*ret_value = NULL;	/*return value			*/
     H5O_fill_new_t  fill = {NULL, 0, NULL, H5D_ALLOC_TIME_LATE, H5D_FILL_TIME_ALLOC, TRUE}; 
-    H5O_fill_t      fill_prop = {NULL, 0, NULL};
+    H5O_fill_t     *fill_prop;          /* Pointer to dataset's fill value area */
     H5O_pline_t pline;                  /* I/O pipeline information */
-    H5O_efl_t   efl;                    /* External file information */
     H5D_layout_t layout;                /* Dataset layout */
     int         chunk_ndims;
     H5P_genplist_t *plist;      /* Property list */
@@ -2123,7 +2140,7 @@ H5D_open_oid(H5G_entry_t *ent)
     assert (ent);
     
     /* Allocate the dataset structure */
-    if(NULL==(dataset = H5D_new(H5P_DEFAULT)))
+    if(NULL==(dataset = H5D_new(H5P_DATASET_CREATE_DEFAULT,FALSE)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* Shallow copy (take ownership) of the group entry object */
@@ -2137,12 +2154,14 @@ H5D_open_oid(H5G_entry_t *ent)
     if (NULL==(dataset->type=H5O_read(&(dataset->ent), H5O_DTYPE, 0, NULL)))
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to load type info from dataset header");
 
+    if (NULL==(dataset->space=H5S_read(&(dataset->ent))))
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to load space info from dataset header");
+
     /* Get dataset creation property list object */
     if (NULL == (plist = H5I_object(dataset->dcpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "can't get dataset creation property list");
 
     /* Get the optional filters message */
-    HDmemset(&pline,0,sizeof(H5O_pline_t));
     if(NULL == H5O_read(&(dataset->ent), H5O_PLINE, 0, &pline)) {
         H5E_clear();
         HDmemset(&pline, 0, sizeof(pline));
@@ -2195,10 +2214,13 @@ H5D_open_oid(H5G_entry_t *ent)
             HGOTO_ERROR(H5E_DATASET, H5E_UNSUPPORTED, NULL, "not implemented yet");
     } /* end switch */
 
+    /* Point at dataset's copy, to cache it for later */
+    fill_prop=&dataset->fill;
+
     /* Retrieve & release the previous fill-value settings */
-    if(H5P_get(plist, H5D_CRT_FILL_VALUE_NAME, &fill_prop) < 0)
+    if(H5P_get(plist, H5D_CRT_FILL_VALUE_NAME, fill_prop) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTSET, NULL, "can't get fill value");
-    H5O_reset(H5O_FILL, &fill_prop);
+    H5O_reset(H5O_FILL, fill_prop);
 
     /* Get the new fill value message */
     if(NULL == H5O_read(&(dataset->ent), H5O_FILL_NEW, 0, &fill)) {
@@ -2224,35 +2246,37 @@ H5D_open_oid(H5G_entry_t *ent)
         } /* end switch */
     } /* end if */
     if(fill.fill_defined) {
-        if(NULL==H5O_copy(H5O_FILL, &fill, &fill_prop))
+        if(NULL==H5O_copy(H5O_FILL, &fill, fill_prop))
             HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "can't copy fill value");
     } else {
 	/* For compatibility with v1.4.  Retrieve the old fill value message.
  	 * If size is 0, make it -1 for undefined. */
-        if(NULL == H5O_read(&(dataset->ent), H5O_FILL, 0, &fill_prop)) {
+        if(NULL == H5O_read(&(dataset->ent), H5O_FILL, 0, fill_prop)) {
             H5E_clear();
-            HDmemset(&fill_prop, 0, sizeof(fill_prop));
+            HDmemset(fill_prop, 0, sizeof(H5O_fill_t));
         }
-        if(fill_prop.size == 0) {
-	    fill_prop.type = fill_prop.buf = NULL;
-	    fill_prop.size = (size_t)-1;
+        if(fill_prop->size == 0) {
+	    fill_prop->type = fill_prop->buf = NULL;
+	    fill_prop->size = (size_t)-1;
 	}
     } /* end else */
 	
-    /* Set fill value properties */ 
-    if(H5P_set(plist, H5D_CRT_FILL_VALUE_NAME, &fill_prop) < 0)
+    /* Set revised fill value properties */ 
+    if(H5P_set(plist, H5D_CRT_FILL_VALUE_NAME, fill_prop) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTSET, NULL, "can't set fill value");
+    dataset->alloc_time=fill.alloc_time;        /* Cache this for later */
     if(H5P_set(plist, H5D_CRT_ALLOC_TIME_NAME, &fill.alloc_time) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTSET, NULL, "can't set fill value");
+    dataset->fill_time=fill.fill_time;          /* Cache this for later */
     if(H5P_set(plist, H5D_CRT_FILL_TIME_NAME, &fill.fill_time) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTSET, NULL, "can't set fill value");
 
     /* Get the external file list message, which might not exist.  Space is
      * also undefined when space allocate time is H5D_ALLOC_TIME_LATE. */
     if( !H5F_addr_defined(dataset->layout.addr)) {
-        HDmemset(&efl,0,sizeof(H5O_efl_t));
-        if(NULL != H5O_read(&(dataset->ent), H5O_EFL, 0, &efl))
-            if(H5P_set(plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
+        HDmemset(&dataset->efl,0,sizeof(H5O_efl_t));
+        if(NULL != H5O_read(&(dataset->ent), H5O_EFL, 0, &dataset->efl))
+            if(H5P_set(plist, H5D_CRT_EXT_FILE_LIST_NAME, &dataset->efl) < 0)
             	HGOTO_ERROR(H5E_DATASET, H5E_CANTSET, NULL, "can't set external file list");
     }
     /*
@@ -2263,7 +2287,7 @@ H5D_open_oid(H5G_entry_t *ent)
     if ((H5F_get_intent(dataset->ent.file) & H5F_ACC_RDWR)
             && (dataset->layout.type!=H5D_COMPACT && dataset->layout.addr==HADDR_UNDEF)
             && (IS_H5FD_MPIO(dataset->ent.file) || IS_H5FD_MPIPOSIX(dataset->ent.file))) {
-        if (H5D_alloc_storage(dataset->ent.file, dataset,H5D_ALLOC_OPEN)<0)
+        if (H5D_alloc_storage(dataset->ent.file, dataset,H5D_ALLOC_OPEN, TRUE, FALSE)<0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, NULL, "unable to initialize file storage");
     }
 
@@ -2274,6 +2298,8 @@ done:
     if (ret_value==NULL && dataset) {
         if (H5F_addr_defined(dataset->ent.header))
             H5O_close(&(dataset->ent));
+        if (dataset->space)
+            H5S_close(dataset->space);
         if (dataset->type)
             H5T_close(dataset->type);
         dataset->ent.file = NULL;
@@ -2317,19 +2343,23 @@ H5D_close(H5D_t *dataset)
     assert(dataset && dataset->ent.file);
 
     /*
-     * Release data type and creation property list -- there isn't much we
-     * can do if one of these fails, so we just continue.
+     * Release datatype, dataspace and creation property list -- there isn't
+     * much we can do if one of these fails, so we just continue.
      */
-    free_failed = (H5T_close(dataset->type) < 0 ||
+    free_failed=(H5T_close(dataset->type)<0 || H5S_close(dataset->space)<0 ||
 			H5I_dec_ref(dataset->dcpl_id) < 0);
 
     /* Update header message of layout for compact dataset. */
     if(dataset->layout.type==H5D_COMPACT && dataset->layout.dirty) {
-        if(H5O_modify(&(dataset->ent), H5O_LAYOUT, 0, 0, &(dataset->layout))<0)
+        if(H5O_modify(&(dataset->ent), H5O_LAYOUT, 0, 0, 1, &(dataset->layout))<0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update layout message");
         dataset->layout.dirty = FALSE;
     } /* end if */
 
+    /* Remove the dataset from the list of opened objects in the file */
+    if(H5FO_delete(dataset->ent.file,dataset->ent.header)<0)
+        HGOTO_ERROR(H5E_DATASET, H5E_CANTRELEASE, FAIL, "can't remove dataset from list of open objects");
+
     /* Close the dataset object */
     H5O_close(&(dataset->ent));
 
@@ -2400,7 +2430,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t
+static herr_t
 H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 	 const H5S_t *file_space, hid_t dxpl_id, void *buf/*out*/)
 {
@@ -2413,8 +2443,11 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     hid_t	src_id = -1, dst_id = -1;/*temporary type atoms */
     H5S_conv_t	*sconv=NULL;	        /*space conversion funcs*/
     H5S_sel_iter_t mem_iter;            /*memory selection iteration info*/
+    hbool_t	mem_iter_init=0;	/*memory selection iteration info has been initialized */
     H5S_sel_iter_t bkg_iter;            /*background iteration info*/
+    hbool_t	bkg_iter_init=0;	/*background iteration info has been initialized */
     H5S_sel_iter_t file_iter;           /*file selection iteration info*/
+    hbool_t	file_iter_init=0;	/*file selection iteration info has been initialized */
     herr_t	ret_value = SUCCEED;	/*return value		*/
     herr_t	status;                 /*function return status*/
     size_t	src_type_size;		/*size of source type	*/
@@ -2422,7 +2455,6 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     size_t	target_size;		/*desired buffer size	*/
     hsize_t	request_nelmts;		/*requested strip mine	*/
     H5T_bkg_t	need_bkg;               /*type of background buf*/
-    H5S_t	*free_this_space=NULL;  /*data space to free	*/
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_dxpl_t *dx = NULL;
     H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;	/*xfer_mode for this request */
@@ -2432,10 +2464,6 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 #ifdef H5S_DEBUG
     H5_timer_t	timer;
 #endif
-    H5O_efl_t   efl;                    /* External File List info */
-    H5O_fill_t  fill;                   /* Fill value info */
-    H5D_fill_time_t	fill_time;      /* When to write the fill values */
-    H5D_fill_value_t	fill_status;    /* Whether/How the fill value is defined */
     H5P_genplist_t *dx_plist=NULL;      /* Data transfer property list */
     H5P_genplist_t *dc_plist;           /* Dataset creation roperty list */
     unsigned	sconv_flags=0;	        /* Flags for the space conversion */
@@ -2447,24 +2475,16 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     assert(mem_type);
     assert(buf);
 
-    /* Initialize these before any errors can occur */
-    HDmemset(&mem_iter,0,sizeof(H5S_sel_iter_t));
-    HDmemset(&bkg_iter,0,sizeof(H5S_sel_iter_t));
-    HDmemset(&file_iter,0,sizeof(H5S_sel_iter_t));
-
     /* Get the dataset's creation property list */
     if (NULL == (dc_plist = H5I_object(dataset->dcpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
 
     /* Get the dataset transfer property list */
-    if (NULL == (dx_plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
+    if (NULL == (dx_plist = H5I_object(dxpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
 
-    if (!file_space) {
-        if (NULL==(free_this_space=H5S_read (&(dataset->ent))))
-            HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to read data space from dataset header");
-        file_space = free_this_space;
-    } /* end if */
+    if (!file_space)
+        file_space = dataset->space;
     if (!mem_space)
         mem_space = file_space;
     nelmts = (*mem_space->select.get_npoints)(mem_space);
@@ -2500,15 +2520,7 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
         HGOTO_ERROR (H5E_ARGS, H5E_BADVALUE, FAIL, "src and dest data spaces have different sizes");
 
     /* Retrieve dataset properties */
-    if(H5P_fill_value_defined(dc_plist, &fill_status)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't tell if fill value defined");
-    if((fill_status==H5D_FILL_VALUE_DEFAULT || fill_status==H5D_FILL_VALUE_USER_DEFINED)
-            && H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL,"can't retrieve fill value");
-    if(H5P_get(dc_plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL,"can't retrieve fill time");
-    if(H5P_get(dc_plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve external file list");
+    /* <none needed in the general case> */
 
     /* If space hasn't been allocated and not using external storage, 
      * return fill value to buffer if fill time is upon allocation, or
@@ -2516,8 +2528,20 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
      * fill time is NEVER, there is no way to tell whether part of data
      * has been overwritten.  So just proceed in reading.     
      */ 
-    if(nelmts > 0 && efl.nused==0 && dataset->layout.type!=H5D_COMPACT 
+    if(nelmts > 0 && dataset->efl.nused==0 && dataset->layout.type!=H5D_COMPACT 
             && dataset->layout.addr==HADDR_UNDEF) {
+        H5O_fill_t  fill;                   /* Fill value info */
+        H5D_fill_time_t	fill_time;      /* When to write the fill values */
+        H5D_fill_value_t	fill_status;    /* Whether/How the fill value is defined */
+
+        /* Retrieve dataset's fill-value properties */
+        if(H5P_fill_value_defined(dc_plist, &fill_status)<0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't tell if fill value defined");
+        if((fill_status==H5D_FILL_VALUE_DEFAULT || fill_status==H5D_FILL_VALUE_USER_DEFINED)
+                && H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL,"can't retrieve fill value");
+        if(H5P_get(dc_plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL,"can't retrieve fill time");
 
         /* Should be impossible, but check anyway... */
         if(fill_status == H5D_FILL_VALUE_UNDEFINED && fill_time == H5D_FILL_TIME_ALLOC)
@@ -2581,10 +2605,10 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 	H5_timer_begin(&timer);
 #endif
   	/* Sanity check dataset, then read it */
-        assert(dataset->layout.addr!=HADDR_UNDEF || efl.nused>0 || dataset->layout.type==H5D_COMPACT);
+        assert(dataset->layout.addr!=HADDR_UNDEF || dataset->efl.nused>0 || dataset->layout.type==H5D_COMPACT);
         status = (sconv->read)(dataset->ent.file, &(dataset->layout), 
-                     dc_plist, H5T_get_size(dataset->type), 
-                     file_space, mem_space, dxpl_id, buf/*out*/);
+             dc_plist, &(dataset->efl), H5T_get_size(dataset->type), 
+             file_space, mem_space, dxpl_id, buf/*out*/);
 #ifdef H5S_DEBUG
         H5_timer_end(&(sconv->stats[1].read_timer), &timer);
         sconv->stats[1].read_nbytes += nelmts * H5T_get_size(dataset->type);
@@ -2636,10 +2660,13 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     /* Figure out the strip mine size. */
     if ((*file_space->select.iter_init)(file_space, src_type_size, &file_iter)<0)
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize file selection information");
+    file_iter_init=1;	/*file selection iteration info has been initialized */
     if ((*mem_space->select.iter_init)(mem_space, dst_type_size, &mem_iter)<0)
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize memory selection information");
+    mem_iter_init=1;	/*file selection iteration info has been initialized */
     if ((*mem_space->select.iter_init)(mem_space, dst_type_size, &bkg_iter)<0)
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize background selection information");
+    bkg_iter_init=1;	/*file selection iteration info has been initialized */
 
     /* Sanity check elements in temporary buffer */
     if (request_nelmts<=0)
@@ -2662,13 +2689,13 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     } /* end else */
     if (NULL==(tconv_buf=H5P_peek_voidp(dx_plist,H5D_XFER_TCONV_BUF_NAME))) {
         /* Allocate temporary buffer */
-        if((tconv_buf=H5FL_BLK_ALLOC(type_conv,target_size,0))==NULL)
+        if((tconv_buf=H5FL_BLK_MALLOC(type_conv,target_size))==NULL)
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for type conversion");
     } /* end if */
     if (need_bkg && NULL==(bkg_buf=H5P_peek_voidp(dx_plist,H5D_XFER_BKGR_BUF_NAME))) {
         /* Allocate background buffer */
         H5_CHECK_OVERFLOW((request_nelmts*dst_type_size),hsize_t,size_t);
-        if((bkg_buf=H5FL_BLK_ALLOC(type_conv,(size_t)(request_nelmts*dst_type_size),0))==NULL)
+        if((bkg_buf=H5FL_BLK_MALLOC(type_conv,(size_t)(request_nelmts*dst_type_size)))==NULL)
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for background conversion");
     } /* end if */
 
@@ -2687,9 +2714,9 @@ H5D_read(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 	H5_timer_begin(&timer);
 #endif
 	/* Sanity check that space is allocated, then read data from it */ 
-        assert(dataset->layout.addr!=HADDR_UNDEF || efl.nused > 0);
+        assert(dataset->layout.addr!=HADDR_UNDEF || dataset->efl.nused > 0);
         n = H5S_select_fgath(dataset->ent.file, &(dataset->layout), 
-                dc_plist, src_type_size, file_space, 
+                dc_plist, &(dataset->efl), src_type_size, file_space, 
                 &file_iter, smine_nelmts, dxpl_id, tconv_buf/*out*/);
 
 #ifdef H5S_DEBUG
@@ -2753,9 +2780,12 @@ done:
     } /* end if */
 #endif /*H5_HAVE_PARALLEL*/
     /* Release selection iterators */
-    (*file_space->select.iter_release)(&file_iter);
-    (*mem_space->select.iter_release)(&mem_iter);
-    (*mem_space->select.iter_release)(&bkg_iter);
+    if(file_iter_init)
+        (*file_space->select.iter_release)(&file_iter);
+    if(mem_iter_init)
+        (*mem_space->select.iter_release)(&mem_iter);
+    if(bkg_iter_init)
+        (*mem_space->select.iter_release)(&bkg_iter);
 
     if (src_id >= 0)
         H5I_dec_ref(src_id);
@@ -2766,8 +2796,6 @@ done:
         H5FL_BLK_FREE(type_conv,tconv_buf);
     if (bkg_buf && NULL==H5P_peek_voidp(dx_plist,H5D_XFER_BKGR_BUF_NAME))
         H5FL_BLK_FREE(type_conv,bkg_buf);
-    if (free_this_space)
-        H5S_close(free_this_space);
     FUNC_LEAVE(ret_value);
 } /* end H5D_read() */
 
@@ -2816,7 +2844,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t
+static herr_t
 H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 	  const H5S_t *file_space, hid_t dxpl_id, const void *buf)
 {
@@ -2829,8 +2857,11 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     hid_t	src_id = -1, dst_id = -1;/*temporary type atoms */
     H5S_conv_t	*sconv=NULL;		/*space conversion funcs*/
     H5S_sel_iter_t mem_iter;            /*memory selection iteration info*/
+    hbool_t	mem_iter_init=0;	/*memory selection iteration info has been initialized */
     H5S_sel_iter_t bkg_iter;            /*background iteration info*/
+    hbool_t	bkg_iter_init=0;	/*background iteration info has been initialized */
     H5S_sel_iter_t file_iter;           /*file selection iteration info*/
+    hbool_t	file_iter_init=0;	/*file selection iteration info has been initialized */
     herr_t	ret_value = SUCCEED;	/*return value		*/
     herr_t	status;                 /*function return status*/
     size_t	src_type_size;		/*size of source type	*/
@@ -2838,7 +2869,6 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     size_t	target_size;		/*desired buffer size	*/
     hsize_t	request_nelmts;		/*requested strip mine	*/
     H5T_bkg_t	need_bkg;		/*type of background buf*/
-    H5S_t	*free_this_space=NULL;	/*data space to free	*/
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_dxpl_t	*dx = NULL;
     H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;	/*xfer_mode for this request */
@@ -2848,10 +2878,6 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 #ifdef H5S_DEBUG
     H5_timer_t	timer;
 #endif
-    H5O_efl_t   efl;                    /* External File List info */
-    H5O_fill_t  fill;                   /* Fill value info */
-    H5D_fill_time_t	fill_time;      /* When to write the fill values */
-    H5D_alloc_time_t    alloc_time;     /* When to allocate raw data space */
     H5P_genplist_t *dx_plist=NULL;      /* Data transfer property list */
     H5P_genplist_t *dc_plist;           /* Dataset creation roperty list */
     unsigned	sconv_flags=0;	        /* Flags for the space conversion */
@@ -2863,24 +2889,16 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     assert(mem_type);
     assert(buf);
 
-    /* Initialize these before any errors can occur */
-    HDmemset(&mem_iter,0,sizeof(H5S_sel_iter_t));
-    HDmemset(&bkg_iter,0,sizeof(H5S_sel_iter_t));
-    HDmemset(&file_iter,0,sizeof(H5S_sel_iter_t));
-
     /* Get the dataset's creation property list */
     if (NULL == (dc_plist = H5I_object(dataset->dcpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
 
     /* Get the dataset transfer property list */
-    if (NULL == (dx_plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
+    if (NULL == (dx_plist = H5I_object(dxpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
 
-    if (!file_space) {
-        if (NULL==(free_this_space=H5S_read (&(dataset->ent))))
-            HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to read data space from dataset header");
-        file_space = free_this_space;
-    } /* end if */
+    if (!file_space)
+        file_space = dataset->space;
     if (!mem_space)                                                                                                                      
         mem_space = file_space;                                                                                                          
     nelmts = (*mem_space->select.get_npoints)(mem_space);            
@@ -2941,20 +2959,19 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 	HGOTO_ERROR (H5E_ARGS, H5E_BADVALUE, FAIL, "src and dest data spaces have different sizes");
 
     /* Retrieve dataset properties */
-    if(H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve fill value");
-    if(H5P_get(dc_plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve fill time");
-    if(H5P_get(dc_plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve external file list");
-    if(H5P_get(dc_plist, H5D_CRT_ALLOC_TIME_NAME, &alloc_time) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve space allocation time");
+    /* <none needed currently> */
 
     /* Allocate data space and initialize it if it hasn't been. */
     if(nelmts > 0 && dataset->layout.type!=H5D_COMPACT &&
             dataset->layout.addr==HADDR_UNDEF) {
+        hssize_t file_nelmts;   /* Number of elements in file dataset's dataspace */
+
+        /* Get the number of elements in file dataset's dataspace */
+        if((file_nelmts=H5S_get_simple_extent_npoints(file_space))<0)
+            HGOTO_ERROR (H5E_DATASET, H5E_BADVALUE, FAIL, "can't retrieve number of elements in file dataset");        
+
  	/* Allocate storage */
-        if(H5D_alloc_storage(dataset->ent.file, dataset,H5D_ALLOC_WRITE)<0)
+        if(H5D_alloc_storage(dataset->ent.file, dataset,H5D_ALLOC_WRITE, TRUE, (hbool_t)((hsize_t)file_nelmts==nelmts ? TRUE : FALSE))<0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize storage");
     } /* end if */
 
@@ -3005,8 +3022,8 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
 	H5_timer_begin(&timer);
 #endif
         status = (sconv->write)(dataset->ent.file, &(dataset->layout),
-                        dc_plist, H5T_get_size(dataset->type),
-                        file_space, mem_space, dxpl_id, buf);
+                dc_plist, &(dataset->efl), H5T_get_size(dataset->type),
+                file_space, mem_space, dxpl_id, buf);
 #ifdef H5S_DEBUG
 	    H5_timer_end(&(sconv->stats[0].write_timer), &timer);
 	    sconv->stats[0].write_nbytes += nelmts * H5T_get_size(mem_type);
@@ -3061,10 +3078,13 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     /* Figure out the strip mine size. */
     if ((*file_space->select.iter_init)(file_space, dst_type_size, &file_iter)<0)
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize file selection information");
+    file_iter_init=1;	/*file selection iteration info has been initialized */
     if ((*mem_space->select.iter_init)(mem_space, src_type_size, &mem_iter)<0)
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize memory selection information");
+    mem_iter_init=1;	/*file selection iteration info has been initialized */
     if ((*file_space->select.iter_init)(file_space, dst_type_size, &bkg_iter)<0)
         HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize background selection information");
+    bkg_iter_init=1;	/*file selection iteration info has been initialized */
      
     /*
      * Get a temporary buffer for type conversion unless the app has already
@@ -3087,13 +3107,13 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
     } /* end else */
     if (NULL==(tconv_buf=H5P_peek_voidp(dx_plist,H5D_XFER_TCONV_BUF_NAME))) {
         /* Allocate temporary buffer */
-        if((tconv_buf=H5FL_BLK_ALLOC(type_conv,target_size,0))==NULL)
+        if((tconv_buf=H5FL_BLK_MALLOC(type_conv,target_size))==NULL)
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for type conversion");
     } /* end if */
     if (need_bkg && NULL==(bkg_buf=H5P_peek_voidp(dx_plist,H5D_XFER_BKGR_BUF_NAME))) {
         /* Allocate background buffer */
         H5_CHECK_OVERFLOW((request_nelmts*dst_type_size),hsize_t,size_t);
-        if((bkg_buf=H5FL_BLK_ALLOC(type_conv,(size_t)(request_nelmts*dst_type_size),1))==NULL)
+        if((bkg_buf=H5FL_BLK_CALLOC(type_conv,(size_t)(request_nelmts*dst_type_size)))==NULL)
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for background conversion");
     } /* end if */
 
@@ -3126,9 +3146,8 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
             H5_timer_begin(&timer);
 #endif
             n = H5S_select_fgath(dataset->ent.file, &(dataset->layout), 
-                                 dc_plist, dst_type_size, file_space, 
-                                 &bkg_iter, smine_nelmts, dxpl_id, 
-                                 bkg_buf/*out*/); 
+                 dc_plist, &(dataset->efl), dst_type_size, file_space, 
+                 &bkg_iter, smine_nelmts, dxpl_id, bkg_buf/*out*/); 
 
 #ifdef H5S_DEBUG
             H5_timer_end(&(sconv->stats[0].bkg_timer), &timer);
@@ -3152,9 +3171,8 @@ H5D_write(H5D_t *dataset, const H5T_t *mem_type, const H5S_t *mem_space,
         H5_timer_begin(&timer);
 #endif
         status = H5S_select_fscat(dataset->ent.file, &(dataset->layout), 
-                                  dc_plist, dst_type_size, 
-                                  file_space, &file_iter, smine_nelmts, 
-                                  dxpl_id, tconv_buf);
+              dc_plist, &(dataset->efl), dst_type_size, file_space, &file_iter,
+              smine_nelmts, dxpl_id, tconv_buf);
 
 #ifdef H5S_DEBUG
         H5_timer_end(&(sconv->stats[0].scat_timer), &timer);
@@ -3186,9 +3204,12 @@ done:
     } /* end if */
 #endif /*H5_HAVE_PARALLEL*/
     /* Release selection iterators */
-    (*file_space->select.iter_release)(&file_iter);
-    (*mem_space->select.iter_release)(&mem_iter);
-    (*file_space->select.iter_release)(&bkg_iter);
+    if(file_iter_init)
+        (*file_space->select.iter_release)(&file_iter);
+    if(mem_iter_init)
+        (*mem_space->select.iter_release)(&mem_iter);
+    if(bkg_iter_init)
+        (*file_space->select.iter_release)(&bkg_iter);
 
     if (src_id >= 0)
         H5I_dec_ref(src_id);
@@ -3199,8 +3220,6 @@ done:
         H5FL_BLK_FREE(type_conv,tconv_buf);
     if (bkg_buf && NULL==H5P_peek_voidp(dx_plist,H5D_XFER_BKGR_BUF_NAME))
         H5FL_BLK_FREE(type_conv,bkg_buf);
-    if (free_this_space)
-        H5S_close(free_this_space);
 
     FUNC_LEAVE(ret_value);
 } /* end H5D_write() */
@@ -3230,8 +3249,6 @@ H5D_extend (H5D_t *dataset, const hsize_t *size)
 {
     int	changed;                        /* Flag to indicate that the dataspace was successfully extended */
     H5S_t	*space = NULL;          /* Dataset's dataspace */
-    H5D_alloc_time_t    alloc_time;     /* When to allocate raw data space */
-    H5P_genplist_t *plist;              /* Property list */
     herr_t	ret_value=SUCCEED;      /* Return value */
 
     FUNC_ENTER_NOAPI(H5D_extend, FAIL);
@@ -3240,12 +3257,6 @@ H5D_extend (H5D_t *dataset, const hsize_t *size)
     assert (dataset);
     assert (size);
 
-    /* Get the dataset creation property list */
-    if (NULL == (plist = H5I_object(dataset->dcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
-    if(H5P_get(plist, H5D_CRT_ALLOC_TIME_NAME, &alloc_time) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve space allocation time");
-
     /*
      * NOTE: Restrictions on extensions were checked when the dataset was
      *	     created.  All extensions are allowed here since none should be
@@ -3253,24 +3264,22 @@ H5D_extend (H5D_t *dataset, const hsize_t *size)
      */
 
     /* Increase the size of the data space */
-    if (NULL==(space=H5S_read (&(dataset->ent))))
-	HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to read data space info from dataset header");
+    space=dataset->space;
     if ((changed=H5S_extend (space, size))<0)
 	HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to increase size of data space");
 
     if (changed>0){
 	/* Save the new dataspace in the file if necessary */
-	if (H5S_modify (&(dataset->ent), space)<0)
+	if (H5S_modify (&(dataset->ent), space, TRUE)<0)
 	    HGOTO_ERROR (H5E_DATASET, H5E_WRITEERROR, FAIL, "unable to update file with new dataspace");
 
 	/* Allocate space for the new parts of the dataset, if appropriate */
-        if(alloc_time==H5D_ALLOC_TIME_EARLY)
-            if (H5D_alloc_storage(dataset->ent.file, dataset, H5D_ALLOC_EXTEND)<0)
+        if(dataset->alloc_time==H5D_ALLOC_TIME_EARLY)
+            if (H5D_alloc_storage(dataset->ent.file, dataset, H5D_ALLOC_EXTEND, TRUE, FALSE)<0)
                 HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize dataset with fill value");
     } /* end if */
 
 done:
-    H5S_close(space);
     FUNC_LEAVE (ret_value);
 }
 
@@ -3347,7 +3356,7 @@ H5D_typeof (H5D_t *dset)
  *
  *-------------------------------------------------------------------------
  */
-H5F_t *
+static H5F_t *
 H5D_get_file (const H5D_t *dset)
 {
     /* Use FUNC_ENTER_NOINIT here to avoid performance issues */
@@ -3379,12 +3388,9 @@ H5D_get_file (const H5D_t *dset)
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5D_alloc_storage (H5F_t *f, H5D_t *dset/*in,out*/, H5D_time_alloc_t time_alloc)
+H5D_alloc_storage (H5F_t *f, H5D_t *dset/*in,out*/, H5D_time_alloc_t time_alloc,
+    hbool_t update_time, hbool_t full_overwrite)
 {
-    H5P_genplist_t     *plist;          /* Dataset's creation property list */
-    H5O_efl_t           efl;            /* External File List info */
-    H5D_fill_time_t fill_time;          /* When to write fill values */
-    H5D_alloc_time_t    alloc_time;     /* When to allocate raw data space */
     struct H5O_layout_t *layout;        /* The dataset's layout information */
     hsize_t	nbytes;                 /* The number of bytes in the dataset */
     unsigned space_allocated=0;         /* Flag to indicate that space was allocated */
@@ -3397,23 +3403,11 @@ H5D_alloc_storage (H5F_t *f, H5D_t *dset/*in,out*/, H5D_time_alloc_t time_alloc)
     assert (f);
     assert (dset);
 
-    /* Get external file list properties */
-    if (NULL == (plist = H5I_object(dset->dcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
-    if(H5P_get(plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve external file list");
-
     /* If the data is stored in external files, don't set an address for the layout
      * We assume that external storage is already
      * allocated by the caller, or at least will be before I/O is performed.
      */
-    if(efl.nused==0) {
-        /* Get properties needed */
-        if(H5P_get(plist, H5D_CRT_FILL_TIME_NAME, &fill_time) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve fill time");
-        if(H5P_get(plist, H5D_CRT_ALLOC_TIME_NAME, &alloc_time) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve space allocation time");
-
+    if(dset->efl.nused==0) {
         /* Get a pointer to the dataset's layout information */
         layout=&(dset->layout);
 
@@ -3441,6 +3435,11 @@ H5D_alloc_storage (H5F_t *f, H5D_t *dset/*in,out*/, H5D_time_alloc_t time_alloc)
                     /* Indicate that we allocated space */
                     space_allocated=1;
                 } /* end if */
+
+                /* If MPIO or MPIPOSIX is used, indicate that space was allocated, so the B-tree gets expanded */
+                if(IS_H5FD_MPIO(f) || IS_H5FD_MPIPOSIX(f))
+                    space_allocated=1;
+
                 break;
 
             case H5D_COMPACT:               
@@ -3462,19 +3461,22 @@ H5D_alloc_storage (H5F_t *f, H5D_t *dset/*in,out*/, H5D_time_alloc_t time_alloc)
                 HGOTO_ERROR (H5E_IO, H5E_UNSUPPORTED, FAIL, "unsupported storage layout");
         } /* end switch */
 
-        /* If we are filling the dataset on allocation, do that now */
-        if(fill_time==H5D_FILL_TIME_ALLOC
-                && !(alloc_time==H5D_ALLOC_TIME_INCR && time_alloc==H5D_ALLOC_WRITE)) {
-            if(H5D_init_storage(dset) < 0)
-                HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize dataset with fill value");
-        } /* end if */
+        /* Check if we actually allocated space before performing other actions */
+        if(space_allocated) {
+            /* If we are filling the dataset on allocation, do that now */
+            if(dset->fill_time==H5D_FILL_TIME_ALLOC
+                    && !(dset->alloc_time==H5D_ALLOC_TIME_INCR && time_alloc==H5D_ALLOC_WRITE)) {
+                if(H5D_init_storage(dset, full_overwrite) < 0)
+                    HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize dataset with fill value");
+            } /* end if */
 
-        /* Also update header message for layout with new address
-          * (this is only for forward compatibility).
-          */
-        if(space_allocated && time_alloc!=H5D_ALLOC_CREATE)
-            if (H5O_modify (&(dset->ent), H5O_LAYOUT, 0, H5O_FLAG_CONSTANT, &(dset->layout)) < 0)
-                HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update layout message");
+            /* Also update header message for layout with new address
+              * (this is only for forward compatibility).
+              */
+            if(time_alloc!=H5D_ALLOC_CREATE)
+                if (H5O_modify (&(dset->ent), H5O_LAYOUT, 0, H5O_FLAG_CONSTANT, update_time, &(dset->layout)) < 0)
+                    HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to update layout message");
+        } /* end if */
     } /* end if */
 
 done:
@@ -3504,13 +3506,11 @@ done:
  *-------------------------------------------------------------------------
  */
 static herr_t
-H5D_init_storage(H5D_t *dset)
+H5D_init_storage(H5D_t *dset, hbool_t full_overwrite)
 {
     hssize_t            snpoints;       /* Number of points in space (for error checking) */
     size_t              npoints;        /* Number of points in space */
-    H5S_t	        *space = NULL;	/* Dataset's dataspace */
-    H5O_fill_t          fill;           /* Fill value information */
-    H5O_efl_t           efl;            /* External File List info */
+    H5S_t	       *space;          /* Dataset's dataspace */
     H5P_genplist_t     *plist;          /* Property list */
     herr_t		ret_value = SUCCEED;    /* Return value */
 
@@ -3518,17 +3518,8 @@ H5D_init_storage(H5D_t *dset)
 
     assert(dset);
 
-    /* Get fill value, external file list, and data pipeline properties */
-    if (NULL == (plist = H5I_object(dset->dcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
-    if(H5P_get(plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get fill value");
-    if(H5P_get(plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve external file list");
-
     /* Get the dataset's dataspace */
-    if (NULL==(space=H5S_read (&(dset->ent))))
-        HGOTO_ERROR (H5E_DATASET, H5E_CANTINIT, FAIL, "unable to read data space from dataset header");
+    space=dset->space;
 
     /* Get the number of elements in the dataset's dataspace */
     snpoints = H5S_get_simple_extent_npoints(space);
@@ -3537,19 +3528,31 @@ H5D_init_storage(H5D_t *dset)
 
     switch (dset->layout.type) {
         case H5D_COMPACT:
-            /* If the fill value is defined, initialize the data buffer with it */
-            if(fill.buf)
-                /* Initialize the cached data buffer with the fill value */
-                H5V_array_fill(dset->layout.buf, fill.buf, fill.size, npoints);
-            else /* If the fill value is default, zero set data buf. */
-                HDmemset(dset->layout.buf, 0, dset->layout.size);
+            /* If we will be immediately overwriting the values, don't bother to clear them */
+            if(!full_overwrite) {
+                /* If the fill value is defined, initialize the data buffer with it */
+                if(dset->fill.buf)
+                    /* Initialize the cached data buffer with the fill value */
+                    H5V_array_fill(dset->layout.buf, dset->fill.buf, dset->fill.size, npoints);
+                else /* If the fill value is default, zero set data buf. */
+                    HDmemset(dset->layout.buf, 0, dset->layout.size);
+            } /* end if */
             break;
 
         case H5D_CONTIGUOUS:
-            if (H5F_contig_fill(dset->ent.file, H5P_DATASET_XFER_DEFAULT,
-                     &(dset->layout), plist, space, H5T_get_size(dset->type))<0)
-                HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to allocate all chunks of dataset");
-             break;
+            /* Don't write default fill values to external files */
+            /* If we will be immediately overwriting the values, don't bother to clear them */
+            if((dset->efl.nused==0 || dset->fill.buf) && !full_overwrite) {
+                /* Get dataset's creation property list */
+                if (NULL == (plist = H5I_object(dset->dcpl_id)))
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
+
+                if (H5F_contig_fill(dset->ent.file, H5P_DATASET_XFER_DEFAULT,
+                         &(dset->layout), plist, &(dset->efl), space,
+                         &dset->fill, H5T_get_size(dset->type))<0)
+                    HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to allocate all chunks of dataset");
+            } /* end if */
+            break;
 
         case H5D_CHUNKED:
             /*        
@@ -3561,21 +3564,22 @@ H5D_init_storage(H5D_t *dset)
                 int             ndims;
                 hsize_t         dim[H5O_LAYOUT_NDIMS];
 
+                /* Get dataset's creation property list */
+                if (NULL == (plist = H5I_object(dset->dcpl_id)))
+                    HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset creation property list");
+
                 if ((ndims=H5S_get_simple_extent_dims(space, dim, NULL))<0)
                      HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to get simple data space info");
                 dim[ndims] = dset->layout.dim[ndims];
 
                 if (H5F_istore_allocate(dset->ent.file, H5P_DATASET_XFER_DEFAULT,
-                         &(dset->layout), dim, plist)<0)
+                         &(dset->layout), dim, plist, full_overwrite)<0)
                     HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to allocate all chunks of dataset");
             } /* end if */
             break;
     } /* end switch */
     
 done:
-    if (space)
-        H5S_close(space);
-
     FUNC_LEAVE(ret_value);
 }
 
@@ -3638,7 +3642,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-hsize_t
+static hsize_t
 H5D_get_storage_size(H5D_t *dset)
 {
     unsigned	u;              /* Index variable */
@@ -3732,7 +3736,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-haddr_t
+static haddr_t
 H5D_get_offset(H5D_t *dset)
 {
     haddr_t	ret_value;
@@ -3894,9 +3898,9 @@ H5Dvlen_reclaim(hid_t type_id, hid_t space_id, hid_t plist_id, void *buf)
     /* Get the default dataset transfer property list if the user didn't provide one */
     if (H5P_DEFAULT == plist_id)
         plist_id= H5P_DATASET_XFER_DEFAULT;
-
-    if (TRUE!=H5P_isa_class(plist_id,H5P_DATASET_XFER))
-	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
+    else
+        if (TRUE!=H5P_isa_class(plist_id,H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not xfer parms");
 
     /* Call H5Diterate with args, etc. */
     ret_value=H5Diterate(buf,type_id,space_id,H5T_vlen_reclaim,&plist_id);
@@ -3923,7 +3927,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-void *
+static void *
 H5D_vlen_get_buf_size_alloc(size_t size, void *info)
 {
     H5T_vlen_bufsize_t *vlen_bufsize=(H5T_vlen_bufsize_t *)info;
@@ -3970,7 +3974,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t
+static herr_t
 H5D_vlen_get_buf_size(void UNUSED *elem, hid_t type_id, hsize_t UNUSED ndim, hssize_t *point, void *op_data)
 {
     H5T_vlen_bufsize_t *vlen_bufsize=(H5T_vlen_bufsize_t *)op_data;
@@ -4060,9 +4064,9 @@ H5Dvlen_get_buf_size(hid_t dataset_id, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTCOPY, FAIL, "can't create dataspace");
 
     /* Grab the temporary buffers required */
-    if((vlen_bufsize.fl_tbuf=H5FL_BLK_ALLOC(vlen_fl_buf,1,0))==NULL)
+    if((vlen_bufsize.fl_tbuf=H5FL_BLK_MALLOC(vlen_fl_buf,1))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "no temporary buffers available");
-    if((vlen_bufsize.vl_tbuf=H5FL_BLK_ALLOC(vlen_vl_buf,1,0))==NULL)
+    if((vlen_bufsize.vl_tbuf=H5FL_BLK_MALLOC(vlen_vl_buf,1))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "no temporary buffers available");
 
     /* Get the pointer to the dataset transfer class */
@@ -4160,7 +4164,7 @@ H5D_fill(const void *fill, const H5T_t *fill_type, void *buf, const H5T_t *buf_t
 
     /* Get the maximum buffer size needed and allocate it */
     buf_size=MAX(src_type_size,dst_type_size);
-    if (NULL==(tconv_buf = H5FL_BLK_ALLOC(type_elem,buf_size,0)) || NULL==(bkg_buf = H5FL_BLK_ALLOC(type_elem,buf_size,1)))
+    if (NULL==(tconv_buf = H5FL_BLK_MALLOC(type_elem,buf_size)) || NULL==(bkg_buf = H5FL_BLK_CALLOC(type_elem,buf_size)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
     /* Copy the user's data into the buffer for conversion */
@@ -4180,7 +4184,7 @@ H5D_fill(const void *fill, const H5T_t *fill_type, void *buf, const H5T_t *buf_t
     }
 
     /* Perform data type conversion */
-    if (H5T_convert(tpath, src_id, dst_id, (hsize_t)1, 0, 0, tconv_buf, bkg_buf, H5P_DEFAULT)<0)
+    if (H5T_convert(tpath, src_id, dst_id, (hsize_t)1, 0, 0, tconv_buf, bkg_buf, H5P_DATASET_XFER_DEFAULT)<0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTCONVERT, FAIL, "data type conversion failed");
 
     /* Fill the selection in the memory buffer */
@@ -4311,7 +4315,7 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-herr_t
+static herr_t
 H5D_set_extent(H5D_t *dset, const hsize_t *size)
 {
     hsize_t                 curr_dims[H5O_LAYOUT_NDIMS];	/* Current dimension sizes */
@@ -4319,7 +4323,6 @@ H5D_set_extent(H5D_t *dset, const hsize_t *size)
     herr_t                  ret_value = SUCCEED;        /* Return value */
     H5S_t                  *space = NULL;
     H5P_genplist_t         *plist;
-    H5D_alloc_time_t        alloc_time;         /* When to allocate raw data space */
     int                     u;
     unsigned                shrink = 0;         /* Flag to indicate a dimension has shrank */
     unsigned                expand = 0;         /* Flag to indicate a dimension has grown */
@@ -4335,8 +4338,7 @@ H5D_set_extent(H5D_t *dset, const hsize_t *size)
   * Get the data space
   *-------------------------------------------------------------------------
   */
-    if(NULL == (space = H5S_read(&(dset->ent))))
-	HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to read data space info from dset header");
+    space = dset->space;
 
  /*-------------------------------------------------------------------------
   * Check if we are shrinking or expanding any of the dimensions
@@ -4361,23 +4363,17 @@ H5D_set_extent(H5D_t *dset, const hsize_t *size)
 
     /* Don't bother updating things, unless they've changed */
     if(changed) {
-        /* Get the dataset creation property list */
-        if(NULL == (plist = H5I_object(dset->dcpl_id)))
-            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dset creation property list");
-        if(H5P_get(plist, H5D_CRT_ALLOC_TIME_NAME, &alloc_time) < 0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't retrieve space allocation time");
-
      /*-------------------------------------------------------------------------
       * Modify the dataset storage
       *-------------------------------------------------------------------------
       */
         /* Save the new dataspace in the file if necessary */
-        if(H5S_modify(&(dset->ent), space) < 0)
+        if(H5S_modify(&(dset->ent), space, TRUE) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "unable to update file with new dataspace");
 
 	/* Allocate space for the new parts of the dataset, if appropriate */
-        if(expand && alloc_time==H5D_ALLOC_TIME_EARLY)
-            if(H5D_alloc_storage(dset->ent.file, dset, H5D_ALLOC_EXTEND) < 0)
+        if(expand && dset->alloc_time==H5D_ALLOC_TIME_EARLY)
+            if(H5D_alloc_storage(dset->ent.file, dset, H5D_ALLOC_EXTEND, TRUE, FALSE) < 0)
                 HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to initialize dataset storage");
 
 
@@ -4387,6 +4383,10 @@ H5D_set_extent(H5D_t *dset, const hsize_t *size)
       *-------------------------------------------------------------------------
       */
         if(shrink && H5D_CHUNKED == dset->layout.type) {
+            /* Get the dataset creation property list */
+            if(NULL == (plist = H5I_object(dset->dcpl_id)))
+                HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dset creation property list");
+
             /* Remove excess chunks */
             if(H5F_istore_prune_by_extent(dset->ent.file, &dset->layout, space) < 0)
                 HGOTO_ERROR(H5E_DATASET, H5E_WRITEERROR, FAIL, "unable to remove chunks ");
@@ -4398,8 +4398,6 @@ H5D_set_extent(H5D_t *dset, const hsize_t *size)
     } /* end if */
 
 done:
-    if(space)
-	H5S_close(space);
     FUNC_LEAVE(ret_value);
 }
 
@@ -4449,7 +4447,7 @@ H5D_flush(H5F_t *f)
             if(NULL==(dataset=H5I_object_verify(id_list[j], H5I_DATASET)))
                 HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to get dataset object");
             if(dataset->layout.type==H5D_COMPACT && dataset->layout.dirty)
-                if(H5O_modify(&(dataset->ent), H5O_LAYOUT, 0, 0, &(dataset->layout))<0)
+                if(H5O_modify(&(dataset->ent), H5O_LAYOUT, 0, 0, 1, &(dataset->layout))<0)
                     HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to update layout message");
             dataset->layout.dirty = FALSE;
         }
@@ -4459,7 +4457,7 @@ done:
     if(id_list!=NULL)
         H5MM_xfree(id_list);
     FUNC_LEAVE(ret_value);
-}
+} /* end H5D_flush() */
 
 
 /*-------------------------------------------------------------------------
diff --git a/src/H5Dcontig.c b/src/H5Dcontig.c
index fce1ba9..a63a9ce 100644
--- a/src/H5Dcontig.c
+++ b/src/H5Dcontig.c
@@ -36,8 +36,11 @@ static int		interface_initialize_g = 0;
 /* Declare a PQ free list to manage the sieve buffer information */
 H5FL_BLK_DEFINE(sieve_buf);
 
-/* Extern the free list to manage blocks of type conversion data */
-H5FL_BLK_EXTERN(type_conv);
+/* Declare the free list to manage blocks of non-zero fill-value data */
+H5FL_BLK_DEFINE_STATIC(non_zero_fill);
+
+/* Declare the free list to manage blocks of zero fill-value data */
+H5FL_BLK_DEFINE_STATIC(zero_fill);
 
 
 /*-------------------------------------------------------------------------
@@ -56,11 +59,10 @@ H5FL_BLK_EXTERN(type_conv);
  */
 herr_t
 H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
-    struct H5P_genplist_t *dc_plist, const struct H5S_t *space,
-    size_t elmt_size)
+    struct H5P_genplist_t *dc_plist, const struct H5O_efl_t *efl,
+    const struct H5S_t *space,
+    const struct H5O_fill_t *fill, size_t elmt_size)
 {
-    H5O_fill_t  fill;           /* Fill value information */
-    H5O_efl_t   efl;            /* External File List info */
     hssize_t    snpoints;       /* Number of points in space (for error checking) */
     size_t      npoints;        /* Number of points in space */
     size_t      ptsperbuf;      /* Maximum # of points which fit in the buffer */
@@ -77,6 +79,7 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
     unsigned    blocks_written=0; /* Flag to indicate that chunk was actually written */
     unsigned    using_mpi=0;    /* Flag to indicate that the file is being accessed with an MPI-capable file driver */
 #endif /* H5_HAVE_PARALLEL */
+    int         non_zero_fill_f=(-1);   /* Indicate that a non-zero fill-value was used */
     herr_t	ret_value=SUCCEED;	/* Return value */
     
     FUNC_ENTER_NOAPI(H5F_contig_fill, FAIL);
@@ -91,12 +94,6 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
     assert(space);
     assert(elmt_size>0);
 
-    /* Get necessary properties from dataset creation property list */
-    if(H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
-        HGOTO_ERROR(H5E_STORAGE, H5E_CANTGET, FAIL, "can't get fill value");
-    if(H5P_get(dc_plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve external file list");
-
 #ifdef H5_HAVE_PARALLEL
     /* Retrieve up MPI parameters */
     if(IS_H5FD_MPIO(f)) {
@@ -136,46 +133,62 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
     assert(snpoints>=0);
     H5_ASSIGN_OVERFLOW(npoints,snpoints,hssize_t,size_t);
 
-    /* Don't write default fill-values to external files */
-    if(efl.nused>0 && !fill.buf)
-        HGOTO_DONE(SUCCEED);
-
-    /* If fill value is library default, use the element size */
-    if(!fill.buf)
-        fill.size=elmt_size;
+    /* If fill value is not library default, use it to set the element size */
+    if(fill->buf)
+        elmt_size=fill->size;
 
     /*
      * Fill the entire current extent with the fill value.  We can do
      * this quite efficiently by making sure we copy the fill value
      * in relatively large pieces.
      */
-     ptsperbuf = MAX(1, bufsize/fill.size);
-     bufsize = ptsperbuf*fill.size;
-
-     /* Allocate temporary buffer */
-     if ((buf=H5FL_BLK_ALLOC(type_conv,bufsize,0))==NULL)
-         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for fill buffer");
-
-     /* Fill the buffer with the user's fill value */
-     if(fill.buf)
-        H5V_array_fill(buf, fill.buf, fill.size, ptsperbuf);
-     else /* Fill the buffer with the default fill value */
-        HDmemset(buf,0,bufsize);
+     ptsperbuf = MAX(1, bufsize/elmt_size);
+     bufsize = ptsperbuf*elmt_size;
+
+    /* Fill the buffer with the user's fill value */
+    if(fill->buf) {
+        /* Allocate temporary buffer */
+        if ((buf=H5FL_BLK_MALLOC(non_zero_fill,bufsize))==NULL)
+            HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for fill buffer");
+
+        H5V_array_fill(buf, fill->buf, elmt_size, ptsperbuf);
+
+        /* Indicate that a non-zero fill buffer was used */
+        non_zero_fill_f=1;
+    } /* end if */
+    else {      /* Fill the buffer with the default fill value */
+        htri_t buf_avail;
+
+        /* Check if there is an already zeroed out buffer available */
+        buf_avail=H5FL_BLK_AVAIL(zero_fill,bufsize);
+        assert(buf_avail!=FAIL);
+
+        /* Allocate temporary buffer (zeroing it if no buffer is available) */
+        if(!buf_avail)
+            buf=H5FL_BLK_CALLOC(zero_fill,bufsize);
+        else
+            buf=H5FL_BLK_MALLOC(zero_fill,bufsize);
+        if(buf==NULL)
+            HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for fill buffer");
+
+        /* Indicate that a zero fill buffer was used */
+        non_zero_fill_f=0;
+    } /* end else */
      
-     /* Start at the beginning of the dataset */
-     addr = 0;
+    /* Start at the beginning of the dataset */
+    addr = 0;
 
-     /* Loop through writing the fill value to the dataset */
-     while (npoints>0) {
-          size = MIN(ptsperbuf, npoints) * fill.size;
+    /* Loop through writing the fill value to the dataset */
+    while (npoints>0) {
+          size = MIN(ptsperbuf, npoints) * elmt_size;
 
 #ifdef H5_HAVE_PARALLEL
             /* Check if this file is accessed with an MPI-capable file driver */
             if(using_mpi) {
                 /* Round-robin write the chunks out from only one process */
                 if(mpi_round==mpi_rank) {
-                    if (H5F_seq_write(f, dxpl_id, layout, dc_plist, space,
-                            fill.size, size, addr, buf)<0)
+                    if (H5F_seq_write(f, dxpl_id, layout, dc_plist, efl, space,
+                            elmt_size, size, addr, buf)<0)
                         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to write fill value to dataset");
                 } /* end if */
                 mpi_round=(++mpi_round)%mpi_size;
@@ -185,8 +198,8 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
             } /* end if */
             else {
 #endif /* H5_HAVE_PARALLEL */
-                if (H5F_seq_write(f, dxpl_id, layout, dc_plist, space,
-                        fill.size, size, addr, buf)<0)
+                if (H5F_seq_write(f, dxpl_id, layout, dc_plist, efl, space,
+                        elmt_size, size, addr, buf)<0)
                     HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to write fill value to dataset");
 #ifdef H5_HAVE_PARALLEL
             } /* end else */
@@ -211,8 +224,13 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
 
 done:
     /* Free the buffer for fill values */
-    if (buf)
-        H5FL_BLK_FREE(type_conv,buf);
+    if (buf) {
+        assert(non_zero_fill_f>=0);
+        if(non_zero_fill_f)
+            H5FL_BLK_FREE(non_zero_fill,buf);
+        else
+            H5FL_BLK_FREE(zero_fill,buf);
+    } /* end if */
 
     FUNC_LEAVE(ret_value);
 }
@@ -661,7 +679,7 @@ H5F_contig_readv(H5F_t *f, hsize_t _max_data, H5FD_mem_t type, haddr_t _addr,
                 } /* end if */
                 else {
                     /* Allocate room for the data sieve buffer */
-                    if (NULL==(f->shared->sieve_buf=H5FL_BLK_ALLOC(sieve_buf,f->shared->sieve_buf_size,0)))
+                    if (NULL==(f->shared->sieve_buf=H5FL_BLK_MALLOC(sieve_buf,f->shared->sieve_buf_size)))
                         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
                     /* Determine the new sieve buffer size & location */
@@ -1128,7 +1146,7 @@ H5F_contig_writev(H5F_t *f, hsize_t _max_data, H5FD_mem_t type, haddr_t _addr,
                 } /* end if */
                 else {
                     /* Allocate room for the data sieve buffer */
-                    if (NULL==(f->shared->sieve_buf=H5FL_BLK_ALLOC(sieve_buf,f->shared->sieve_buf_size,0)))
+                    if (NULL==(f->shared->sieve_buf=H5FL_BLK_MALLOC(sieve_buf,f->shared->sieve_buf_size)))
                         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
                     /* Determine the new sieve buffer size & location */
diff --git a/src/H5Distore.c b/src/H5Distore.c
index ea74165..f617092 100644
--- a/src/H5Distore.c
+++ b/src/H5Distore.c
@@ -862,7 +862,7 @@ H5F_istore_init (H5F_t *f)
     HDmemset (rdcc, 0, sizeof(H5F_rdcc_t));
     if (f->shared->rdcc_nbytes>0 && f->shared->rdcc_nelmts>0) {
 	rdcc->nslots = f->shared->rdcc_nelmts;
-	rdcc->slot = H5FL_ARR_ALLOC (H5F_rdcc_ent_ptr_t,rdcc->nslots,1);
+	rdcc->slot = H5FL_ARR_CALLOC (H5F_rdcc_ent_ptr_t,rdcc->nslots);
 	if (NULL==rdcc->slot)
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     }
@@ -1440,7 +1440,7 @@ H5F_istore_lock(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
             HGOTO_ERROR(H5E_IO, H5E_CANTINIT, NULL, "unable to preempt chunk(s) from cache");
 
         /* Create a new entry */
-        ent = H5FL_ALLOC(H5F_rdcc_ent_t,0);
+        ent = H5FL_MALLOC(H5F_rdcc_ent_t);
         ent->locked = 0;
         ent->dirty = FALSE;
         ent->chunk_size = chunk_size;
@@ -1943,8 +1943,9 @@ H5F_istore_write(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
             /* Additional sanity check when operating in parallel */
-            if (chunk_addr==HADDR_UNDEF || pline.nfilters>0)
+            if (chunk_addr==HADDR_UNDEF || pline.nfilters>0) {
                 HGOTO_ERROR (H5E_IO, H5E_WRITEERROR, FAIL, "unable to locate raw data chunk");
+            }
 #endif /* H5_HAVE_PARALLEL */
             
             /*
@@ -2312,7 +2313,7 @@ done:
  */
 herr_t
 H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
-		    const hsize_t *space_dim, H5P_genplist_t *dc_plist)
+        const hsize_t *space_dim, H5P_genplist_t *dc_plist, hbool_t full_overwrite)
 {
     hssize_t	chunk_offset[H5O_LAYOUT_NDIMS]; /* Offset of current chunk */
     hsize_t	chunk_size;     /* Size of chunk in bytes */
@@ -2407,7 +2408,7 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     } /* end for */
 
     /* Check if fill values should be written to blocks */
-    if(fill_time != H5D_FILL_TIME_NEVER) {
+    if(fill_time != H5D_FILL_TIME_NEVER && !full_overwrite) {
         /* Allocate chunk buffer for processes to use when writing fill values */
         H5_CHECK_OVERFLOW(chunk_size,hsize_t,size_t);
         if (NULL==(chunk = H5MM_malloc((size_t)chunk_size)))
@@ -2484,7 +2485,7 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
                 HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to allocate chunk");
 
             /* Check if fill values should be written to blocks */
-            if(fill_time != H5D_FILL_TIME_NEVER) {
+            if(fill_time != H5D_FILL_TIME_NEVER && !full_overwrite) {
 #ifdef H5_HAVE_PARALLEL
                 /* Check if this file is accessed with an MPI-capable file driver */
                 if(using_mpi) {
diff --git a/src/H5Dprivate.h b/src/H5Dprivate.h
index 7f2a0ce..cfef073 100644
--- a/src/H5Dprivate.h
+++ b/src/H5Dprivate.h
@@ -147,44 +147,24 @@
 typedef struct H5D_t {
     H5G_entry_t         ent;            /* cached object header stuff   */
     H5T_t              *type;           /* datatype of this dataset     */
+    H5S_t              *space;          /* dataspace of this dataset    */
     hid_t               dcpl_id;        /* dataset creation property id */
     H5O_layout_t        layout;         /* data layout                  */
+    /* Cache some frequently accessed values from the DCPL */
+    H5O_efl_t           efl;            /* External file list information */
+    H5D_alloc_time_t    alloc_time;     /* Dataset allocation time      */
+    H5D_fill_time_t	fill_time;	/* Dataset fill value writing time */
+    H5O_fill_t          fill;           /* Dataset fill value information */
 } H5D_t;
   
 /* Functions defined in H5D.c */
 H5_DLL herr_t H5D_init(void);
-
-H5_DLL herr_t H5D_update_entry_cache(H5F_t *f, H5G_entry_t *ent, H5G_entry_t *loc,
-                                     const char *name, const H5S_t *space,
-                                     H5P_genplist_t *new_plist, H5O_layout_t *layout,
-                                     H5T_t *type, hbool_t allocate_header,
-                                     haddr_t header);
-H5_DLL herr_t H5D_update_external_storage_cache(H5F_t *file, H5G_entry_t *ent,
-                                                H5O_efl_t *efl, H5O_layout_t *layout);
-
-H5_DLL H5D_t *H5D_create(H5G_entry_t *loc, const char *name, 
-                          const H5T_t *type, const H5S_t *space, 
-                          hid_t dcpl_id);
-H5_DLL H5D_t *H5D_open(H5G_entry_t *loc, const char *name);
+H5_DLL hid_t H5D_open(H5G_entry_t *ent);
 H5_DLL herr_t H5D_close(H5D_t *dataset);
 H5_DLL htri_t H5D_isa(H5G_entry_t *ent);
-H5_DLL herr_t H5D_read(H5D_t *dataset, const H5T_t *mem_type,
-			const H5S_t *mem_space, const H5S_t *file_space,
-			hid_t dset_xfer_plist, void *buf/*out*/);
-H5_DLL herr_t H5D_write(H5D_t *dataset, const H5T_t *mem_type,
-			 const H5S_t *mem_space, const H5S_t *file_space,
-			 hid_t dset_xfer_plist, const void *buf);
 H5_DLL herr_t H5D_extend(H5D_t *dataset, const hsize_t *size);
 H5_DLL H5G_entry_t *H5D_entof(H5D_t *dataset);
 H5_DLL H5T_t *H5D_typeof(H5D_t *dset);
-H5_DLL H5S_t *H5D_get_space(H5D_t *dset);
-H5_DLL H5D_t * H5D_open_oid(H5G_entry_t *ent);
-H5_DLL H5F_t * H5D_get_file(const H5D_t *dset);
-H5_DLL hsize_t H5D_get_storage_size(H5D_t *dset);
-H5_DLL haddr_t H5D_get_offset(H5D_t *dset);
-H5_DLL void *H5D_vlen_get_buf_size_alloc(size_t size, void *info);
-H5_DLL herr_t H5D_vlen_get_buf_size(void *elem, hid_t type_id, hsize_t ndim, 
-                                     hssize_t *point, void *op_data);
 H5_DLL herr_t H5D_crt_copy(hid_t new_plist_t, hid_t old_plist_t, 
                             void *copy_data);
 H5_DLL herr_t H5D_crt_close(hid_t dxpl_id, void *close_data);
@@ -192,7 +172,6 @@ H5_DLL herr_t H5D_xfer_create(hid_t dxpl_id, void *create_data);
 H5_DLL herr_t H5D_xfer_copy(hid_t new_plist_id, hid_t old_plist_id, 
                              void *copy_data);
 H5_DLL herr_t H5D_xfer_close(hid_t dxpl_id, void *close_data);
-H5_DLL herr_t H5D_set_extent(H5D_t *dataset, const hsize_t *size);
 H5_DLL herr_t H5D_flush(H5F_t *f);
 
 
diff --git a/src/H5Dseq.c b/src/H5Dseq.c
index 6176003..9592725 100644
--- a/src/H5Dseq.c
+++ b/src/H5Dseq.c
@@ -59,9 +59,9 @@ static int interface_initialize_g = 0;
  */
 herr_t
 H5F_seq_read(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist,
-        const H5S_t *file_space, size_t elmt_size,
-        size_t seq_len, hsize_t dset_offset, void *buf/*out*/)
+    H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
+    const H5S_t *file_space, size_t elmt_size,
+    size_t seq_len, hsize_t dset_offset, void *buf/*out*/)
 {
     herr_t      ret_value=SUCCEED;       /* Return value */
 
@@ -70,10 +70,11 @@ H5F_seq_read(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     /* Check args */
     assert(f);
     assert(layout);
+    assert(efl);
     assert(buf);
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
 
-    if (H5F_seq_readv(f, dxpl_id, layout, dc_plist, file_space, elmt_size, 1, &seq_len, &dset_offset, buf)<0)
+    if (H5F_seq_readv(f, dxpl_id, layout, dc_plist, efl, file_space, elmt_size, 1, &seq_len, &dset_offset, buf)<0)
         HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "vector read failed");
 
 done:
@@ -104,9 +105,9 @@ done:
  */
 herr_t
 H5F_seq_write(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist,
-        const H5S_t *file_space, size_t elmt_size,
-        size_t seq_len, hsize_t dset_offset, const void *buf)
+    H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
+    const H5S_t *file_space, size_t elmt_size,
+    size_t seq_len, hsize_t dset_offset, const void *buf)
 {
     herr_t      ret_value=SUCCEED;       /* Return value */
 
@@ -115,10 +116,11 @@ H5F_seq_write(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
     /* Check args */
     assert(f);
     assert(layout);
+    assert(efl);
     assert(buf);
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
 
-    if (H5F_seq_writev(f, dxpl_id, layout, dc_plist, file_space, elmt_size, 1, &seq_len, &dset_offset, buf)<0)
+    if (H5F_seq_writev(f, dxpl_id, layout, dc_plist, efl, file_space, elmt_size, 1, &seq_len, &dset_offset, buf)<0)
         HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "vector write failed");
 
 done:
@@ -151,7 +153,7 @@ done:
  */
 herr_t
 H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist,
+        H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
         const H5S_t *file_space, size_t elmt_size,
         size_t nseq, size_t seq_len_arr[], hsize_t dset_offset_arr[],
         void *_buf/*out*/)
@@ -172,7 +174,6 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     unsigned	u;				/*counters		*/
     size_t      v;                              /*counters              */
     int	i,j;				/*counters		*/
-    struct H5O_efl_t efl;               /* External File List info */
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;
     H5P_genplist_t *plist=NULL;                 /* Property list */
@@ -184,6 +185,7 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     /* Check args */
     assert(f);
     assert(layout);
+    assert(efl);
     assert(real_buf);
     /* Make certain we have the correct type of property list */
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
@@ -221,14 +223,10 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
         HGOTO_ERROR (H5E_DATASET, H5E_READERROR, FAIL, "collective access on non-contiguous datasets not supported yet");
 #endif /* H5_HAVE_PARALLEL */
 
-    /* Get necessary properties from property list */
-    if(H5P_get(dc_plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get EFL value");
-
     switch (layout->type) {
         case H5D_CONTIGUOUS:
             /* Read directly from file if the dataset is in an external file */
-            if (efl.nused>0) {
+            if (efl->nused>0) {
                 /* Iterate through the sequence vectors */
                 for(v=0; v<nseq; v++) {
 #ifdef H5_HAVE_PARALLEL
@@ -260,7 +258,7 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
                      *  file offsets, totally mixing up the data sieve buffer information. -QAK
                      */
                     H5_CHECK_OVERFLOW(dset_offset_arr[v],hsize_t,haddr_t);
-                    if (H5O_efl_read(f, &efl, (haddr_t)dset_offset_arr[v], seq_len_arr[v], real_buf)<0)
+                    if (H5O_efl_read(f, efl, (haddr_t)dset_offset_arr[v], seq_len_arr[v], real_buf)<0)
                         HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "external data read failed");
 
                     /* Increment offset in buffer */
@@ -281,7 +279,7 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
             /*
              * This method is unable to access external raw data files 
              */
-            if (efl.nused>0)
+            if (efl->nused>0)
                 HGOTO_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "chunking and external files are mutually exclusive");
 
             /* Compute the file offset coordinates and hyperslab size */
@@ -542,7 +540,7 @@ done:
  */
 herr_t
 H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist,
+        H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
         const H5S_t *file_space, size_t elmt_size,
         size_t nseq, size_t seq_len_arr[], hsize_t dset_offset_arr[],
         const void *_buf)
@@ -563,7 +561,6 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
     unsigned	u;				/*counters		*/
     size_t      v;                              /*counters              */
     int	i,j;				/*counters		*/
-    struct H5O_efl_t efl;               /* External File List info */
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;
     H5P_genplist_t *plist=NULL;                 /* Property list */
@@ -575,6 +572,7 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
     /* Check args */
     assert(f);
     assert(layout);
+    assert(efl);
     assert(real_buf);
     /* Make certain we have the correct type of property list */
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
@@ -612,14 +610,10 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
         HGOTO_ERROR (H5E_DATASET, H5E_WRITEERROR, FAIL, "collective access on chunked datasets not supported yet");
 #endif /* H5_HAVE_PARALLEL */
 
-    /* Get necessary properties from property list */
-    if(H5P_get(dc_plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get EFL value");
-
     switch (layout->type) {
         case H5D_CONTIGUOUS:
             /* Write directly to file if the dataset is in an external file */
-            if (efl.nused>0) {
+            if (efl->nused>0) {
                 /* Iterate through the sequence vectors */
                 for(v=0; v<nseq; v++) {
 #ifdef H5_HAVE_PARALLEL
@@ -650,7 +644,7 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
                      *  file offsets, totally mixing up the data sieve buffer information. -QAK
                      */
                     H5_CHECK_OVERFLOW(dset_offset_arr[v],hsize_t,haddr_t);
-                    if (H5O_efl_write(f, &efl, (haddr_t)dset_offset_arr[v], seq_len_arr[v], real_buf)<0)
+                    if (H5O_efl_write(f, efl, (haddr_t)dset_offset_arr[v], seq_len_arr[v], real_buf)<0)
                         HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "external data write failed");
 
                     /* Increment offset in buffer */
@@ -671,7 +665,7 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
             /*
              * This method is unable to access external raw data files 
              */
-            if (efl.nused>0)
+            if (efl->nused>0)
                 HGOTO_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "chunking and external files are mutually exclusive");
 
             /* Compute the file offset coordinates and hyperslab size */
diff --git a/src/H5E.c b/src/H5E.c
index 98bfe1d..8b9ab13 100644
--- a/src/H5E.c
+++ b/src/H5E.c
@@ -72,6 +72,8 @@ static const H5E_major_mesg_t H5E_major_mesg_g[] = {
     {H5E_VFL,		"Virtual File Layer"},
     {H5E_TBBT,		"Threaded, Balanced, Binary Trees"},
     {H5E_FPHDF5,	"Flexible Parallel HDF5"},
+    {H5E_TST,		"Ternary Search Trees"},
+    {H5E_RS,		"Reference Counted Strings"},
 };
 
 static const H5E_minor_mesg_t H5E_minor_mesg_g[] = {
diff --git a/src/H5Epublic.h b/src/H5Epublic.h
index 09e5af2..607bbf2 100644
--- a/src/H5Epublic.h
+++ b/src/H5Epublic.h
@@ -101,7 +101,9 @@ typedef enum H5E_major_t {
     H5E_REFERENCE,              /*References                                 */
     H5E_VFL,			/*Virtual File Layer			     */
     H5E_TBBT, 		        /*Threaded, Balanced, Binary Trees           */
-    H5E_FPHDF5		        /*Flexible Parallel HDF5                     */
+    H5E_FPHDF5,		        /*Flexible Parallel HDF5                     */
+    H5E_TST, 		        /*Ternary Search Trees                       */
+    H5E_RS  		        /*Reference Counted Strings                  */
 } H5E_major_t;
 
 /* Declare an enumerated type which holds all the valid minor HDF error codes */
diff --git a/src/H5F.c b/src/H5F.c
index 492dc42..bafda9a 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -243,7 +243,7 @@ H5F_init_interface(void)
     assert(H5P_CLS_FILE_CREATE_g!=-1);
 
     /* Get the pointer to file creation class */
-    if(NULL == (crt_pclass = H5I_object_verify(H5P_CLS_FILE_CREATE_g, H5I_GENPROP_CLS)))
+    if(NULL == (crt_pclass = H5I_object(H5P_CLS_FILE_CREATE_g)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list class");
 
     /* Get the number of properties in the class */
@@ -326,7 +326,7 @@ H5F_init_interface(void)
     assert(H5P_CLS_FILE_ACCESS_g!=-1);
 
     /* Get the pointer to file creation class */
-    if(NULL == (acs_pclass = H5I_object_verify(H5P_CLS_FILE_ACCESS_g, H5I_GENPROP_CLS)))
+    if(NULL == (acs_pclass = H5I_object(H5P_CLS_FILE_ACCESS_g)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list class");
 
     /* Get the number of properties in the class */
@@ -407,7 +407,7 @@ H5F_init_interface(void)
     assert(H5P_CLS_MOUNT_g!=-1);
 
     /* Get the pointer to file mount class */
-    if(NULL == (mnt_pclass = H5I_object_verify(H5P_CLS_MOUNT_g, H5I_GENPROP_CLS)))
+    if(NULL == (mnt_pclass = H5I_object(H5P_CLS_MOUNT_g)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list class");
 
     /* Get the number of properties in the class */
@@ -503,7 +503,7 @@ H5F_acs_create(hid_t fapl_id, void UNUSED *copy_data)
     FUNC_ENTER_NOAPI(H5F_acs_create, FAIL);
 
     /* Check argument */
-    if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
+    if(NULL == (plist = H5I_object(fapl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list");
 
     /* Retrieve properties */
@@ -558,7 +558,7 @@ H5F_acs_close(hid_t fapl_id, void UNUSED *close_data)
     FUNC_ENTER_NOAPI(H5F_acs_close, FAIL);
 
     /* Check argument */
-    if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
+    if(NULL == (plist = H5I_object(fapl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list");
 
     if(H5P_get(plist, H5F_ACS_FILE_DRV_ID_NAME, &driver_id) < 0)
@@ -610,9 +610,9 @@ H5F_acs_copy(hid_t new_fapl_id, hid_t old_fapl_id, void UNUSED *copy_data)
 
     FUNC_ENTER_NOAPI(H5F_acs_copy, FAIL);
 
-    if(NULL == (new_plist = H5I_object_verify(new_fapl_id, H5I_GENPROP_LST)))
+    if(NULL == (new_plist = H5I_object(new_fapl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "can't get property list");
-    if(NULL == (old_plist = H5I_object_verify(old_fapl_id, H5I_GENPROP_LST)))
+    if(NULL == (old_plist = H5I_object(old_fapl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "can't get property list");
 
     /* Get values from old property list */
@@ -1375,7 +1375,7 @@ H5Fis_hdf5(const char *name)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADRANGE, FAIL, "no file name specified");
 
     /* Open the file at the virtual file layer */
-    if (NULL==(file=H5FD_open(name, H5F_ACC_RDONLY, H5P_DEFAULT, HADDR_UNDEF)))
+    if (NULL==(file=H5FD_open(name, H5F_ACC_RDONLY, H5P_FILE_ACCESS_DEFAULT, HADDR_UNDEF)))
 	HGOTO_ERROR(H5E_IO, H5E_CANTINIT, FAIL, "unable to open file");
 
     /* The file is an hdf5 file if the hdf5 file signature can be found */
@@ -1428,13 +1428,13 @@ H5F_new(H5F_file_t *shared, hid_t fcpl_id, hid_t fapl_id)
  
     FUNC_ENTER_NOINIT(H5F_new);
 
-    if (NULL==(f=H5FL_ALLOC(H5F_t,1)))
+    if (NULL==(f=H5FL_CALLOC(H5F_t)))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     if (shared) {
 	f->shared = shared;
     } else {
-	f->shared = H5FL_ALLOC(H5F_file_t,1);
+	f->shared = H5FL_CALLOC(H5F_file_t);
 	f->shared->boot_addr = HADDR_UNDEF;
 	f->shared->base_addr = HADDR_UNDEF;
 	f->shared->freespace_addr = HADDR_UNDEF;
@@ -1445,16 +1445,19 @@ H5F_new(H5F_file_t *shared, hid_t fcpl_id, hid_t fapl_id)
 	 * new file handle.  We do this early because some values might need
 	 * to change as the file is being opened.
 	 */
-        if(H5P_DEFAULT == fcpl_id)
-            fcpl_id = H5P_FILE_CREATE_DEFAULT;
-        if(NULL == (plist = H5P_object_verify(fcpl_id,H5P_FILE_CREATE)))
+        if(NULL == (plist = H5I_object(fcpl_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not property list");
         f->shared->fcpl_id = H5P_copy_plist(plist);
 
+        /* Get the FCPL values to cache */
+        if(H5P_get(plist, H5F_CRT_ADDR_BYTE_NUM_NAME, &f->shared->sizeof_addr)<0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get byte number for address");
+        if(H5P_get(plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &f->shared->sizeof_size)<0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get byte number for object size");
+        if(H5P_get(plist, H5F_CRT_SYM_LEAF_NAME, &f->shared->sym_leaf_k)<0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get byte number for object size");
 
-        if(H5P_DEFAULT == fapl_id)
-            fapl_id = H5P_FILE_ACCESS_DEFAULT;
-        if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
+        if(NULL == (plist = H5I_object(fapl_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not file access property list");
 
         if(H5P_get(plist, H5F_ACS_META_CACHE_SIZE_NAME, &(f->shared->mdc_nelmts)) < 0)
@@ -1486,6 +1489,10 @@ H5F_new(H5F_file_t *shared, hid_t fcpl_id, hid_t fapl_id)
 
 	/* Create the chunk cache */
 	H5F_istore_init(f);
+
+        /* Create the file's "open object" information */
+        if(H5FO_create(f)<0)
+	    HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, NULL, "unable to create open object TBBT");
     } /* end else */
     
     f->shared->nrefs++;
@@ -1561,13 +1568,17 @@ H5F_dest(H5F_t *f)
                 f->shared->root_grp=NULL;
             }
 	    if (H5AC_dest(f)) {
-		HERROR(H5E_FILE, H5E_CANTINIT, "problems closing file");
+		HERROR(H5E_FILE, H5E_CANTRELEASE, "problems closing file");
 		ret_value = FAIL; /*but keep going*/
 	    }
 	    if (H5F_istore_dest (f)<0) {
-		HERROR(H5E_FILE, H5E_CANTINIT, "problems closing file");
+		HERROR(H5E_FILE, H5E_CANTRELEASE, "problems closing file");
 		ret_value = FAIL; /*but keep going*/
 	    }
+	    if (H5FO_dest(f)<0) {
+                HERROR(H5E_FILE, H5E_CANTRELEASE, "problems closing file");
+                ret_value = FAIL; /*but keep going*/
+	    } /* end if */
 	    f->shared->cwfs = H5MM_xfree (f->shared->cwfs);
 
             /* Free the data sieve buffer, if it's been allocated */
@@ -1837,6 +1848,16 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
      * empty or not.
      */
     if (0==H5FD_get_eof(lf) && (flags & H5F_ACC_RDWR)) {
+        /* Get values to cache from the FCPL */
+        if(H5P_get(c_plist, H5F_CRT_ADDR_BYTE_NUM_NAME,&shared->sizeof_addr)<0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set byte number in an address");
+        if(H5P_get(c_plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &shared->sizeof_size)<0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set byte number for object size");
+        if(H5P_get(c_plist, H5F_CRT_SYM_LEAF_NAME, &shared->sym_leaf_k)<0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set rank for symbol table leaf nodes");
+        if(H5P_get(c_plist, H5F_CRT_BTREE_RANK_NAME, &shared->btree_k[0])<0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "unable to get rank for btree internal nodes");        
+
 	/*
 	 * The superblock starts immediately after the user-defined header,
 	 * which we have already insured is a proper size.  The base address
@@ -1903,6 +1924,7 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
 	    HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number in an address");
         if(H5P_set(c_plist, H5F_CRT_ADDR_BYTE_NUM_NAME,&sizeof_addr)<0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set byte number in an address");
+        shared->sizeof_addr=sizeof_addr;        /* Keep a local copy also */
 
 	/* Size of file sizes */
         sizeof_size = *p++;
@@ -1911,6 +1933,7 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
 	    HGOTO_ERROR(H5E_FILE, H5E_BADVALUE, NULL, "bad byte number for object size");
         if(H5P_set(c_plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &sizeof_size)<0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set byte number for object size");
+        shared->sizeof_size=sizeof_size;        /* Keep a local copy also */
 	
 	/* Reserved byte */
 	p++;
@@ -1921,6 +1944,7 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
 	    HGOTO_ERROR(H5E_FILE, H5E_BADRANGE, NULL, "bad symbol table leaf node 1/2 rank");
         if(H5P_set(c_plist, H5F_CRT_SYM_LEAF_NAME, &sym_leaf_k)<0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set rank for symbol table leaf nodes");
+        shared->sym_leaf_k=sym_leaf_k;        /* Keep a local copy also */
 
 	/* Need 'get' call to set other array values */
         if(H5P_get(c_plist, H5F_CRT_BTREE_RANK_NAME, btree_k)<0)
@@ -1930,6 +1954,7 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
 	    HGOTO_ERROR(H5E_FILE, H5E_BADRANGE, NULL, "bad 1/2 rank for btree internal nodes");
         if(H5P_set(c_plist, H5F_CRT_BTREE_RANK_NAME, btree_k)<0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTSET, NULL, "unable to set rank for btree internal nodes");
+        HDmemcpy(shared->btree_k,btree_k,sizeof(int)*H5B_NUM_BTREE_ID); /* Keep a local copy also */
 
 	/* File consistency flags. Not really used yet */
 	UINT32DECODE(p, shared->consist_flags);
@@ -2033,9 +2058,7 @@ H5F_open(const char *name, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
      * second time or later, verify the access property list value matches
      * the degree in shared file structure.
      */
-    if(H5P_DEFAULT == fapl_id)
-        fapl_id = H5P_FILE_ACCESS_DEFAULT;
-    if(NULL == (a_plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
+    if(NULL == (a_plist = H5I_object(fapl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not file access property list");
     if(H5P_get(a_plist, H5F_CLOSE_DEGREE_NAME, &fc_degree) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get file close degree");  
@@ -2138,14 +2161,16 @@ H5Fcreate(const char *filename, unsigned flags, hid_t fcpl_id,
     /* Check file creation property list */
     if(H5P_DEFAULT == fcpl_id)
         fcpl_id = H5P_FILE_CREATE_DEFAULT;
-    if(TRUE != H5P_isa_class(fcpl_id, H5P_FILE_CREATE))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file create property list");
+    else
+        if(TRUE != H5P_isa_class(fcpl_id, H5P_FILE_CREATE))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file create property list");
 
     /* Check the file access property list */
     if(H5P_DEFAULT == fapl_id)
         fapl_id = H5P_FILE_ACCESS_DEFAULT;
-    if(TRUE != H5P_isa_class(fapl_id, H5P_FILE_ACCESS))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file access property list");
+    else
+        if(TRUE != H5P_isa_class(fapl_id, H5P_FILE_ACCESS))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file access property list");
 
     /*
      * Adjust bit flags by turning on the creation bit and making sure that
@@ -2230,11 +2255,12 @@ H5Fopen(const char *filename, unsigned flags, hid_t fapl_id)
 	HGOTO_ERROR (H5E_ARGS, H5E_BADVALUE, FAIL, "invalid file open flags");
     if(H5P_DEFAULT == fapl_id)
         fapl_id = H5P_FILE_ACCESS_DEFAULT;
-    if(TRUE != H5P_isa_class(fapl_id, H5P_FILE_ACCESS))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file access property list");
+    else
+        if(TRUE != H5P_isa_class(fapl_id, H5P_FILE_ACCESS))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not file access property list");
 
     /* Open the file */
-    if (NULL==(new_file=H5F_open(filename, flags, H5P_DEFAULT, fapl_id)))
+    if (NULL==(new_file=H5F_open(filename, flags, H5P_FILE_CREATE_DEFAULT, fapl_id)))
 	HGOTO_ERROR(H5E_FILE, H5E_CANTOPENFILE, FAIL, "unable to open file");
 
     /* Get an atom for the file */
@@ -2399,8 +2425,6 @@ H5F_flush(H5F_t *f, H5F_scope_t scope, hbool_t invalidate,
     int                 freespace_vers; /* Freespace info version */
     int                 obj_dir_vers;   /* Object header info version */
     int                 share_head_vers;/* Shared header info version */
-    int                 btree_k[H5B_NUM_BTREE_ID];      /* B-tree size info */
-    unsigned            sym_leaf_k;     /* Number of symbols in B-tree leafs */
     H5P_genplist_t *plist;              /* Property list */
     herr_t              ret_value;      /* Return value */
     
@@ -2492,10 +2516,6 @@ H5F_flush(H5F_t *f, H5F_scope_t scope, hbool_t invalidate,
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get object directory version");
     if(H5P_get(plist, H5F_CRT_SHARE_HEAD_VERS_NAME, &share_head_vers) < 0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get shared-header format version");
-    if(H5P_get(plist, H5F_CRT_SYM_LEAF_NAME, &sym_leaf_k) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get rank for symbol table leaf nodes");
-    if(H5P_get(plist, H5F_CRT_BTREE_RANK_NAME, btree_k) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get rank for btree internal nodes");
 
     /* encode the file boot block */
     p = sbuf;
@@ -2511,8 +2531,8 @@ H5F_flush(H5F_t *f, H5F_scope_t scope, hbool_t invalidate,
     assert (H5F_SIZEOF_SIZE(f)<=255);
     *p++ = (uint8_t)H5F_SIZEOF_SIZE(f);
     *p++ = 0;			/*reserved */
-    UINT16ENCODE(p, sym_leaf_k);
-    UINT16ENCODE(p, btree_k[H5B_SNODE_ID]);
+    UINT16ENCODE(p, f->shared->sym_leaf_k);
+    UINT16ENCODE(p, f->shared->btree_k[H5B_SNODE_ID]);
     UINT32ENCODE(p, f->shared->consist_flags);    
     H5F_addr_encode(f, &p, f->shared->base_addr);
     H5F_addr_encode(f, &p, f->shared->freespace_addr);
@@ -2904,6 +2924,7 @@ H5F_mount(H5G_entry_t *loc, const char *name, H5F_t *child,
     H5F_t	*parent = NULL;		/*file containing mount point	*/
     int	lt, rt, md, cmp;	/*binary search indices		*/
     H5G_entry_t	*ent = NULL;		/*temporary symbol table entry	*/
+    H5RS_str_t  *name_r;                /* Ref-counted version of name */
     herr_t	ret_value = SUCCEED;	/*return value			*/
     
     FUNC_ENTER_NOINIT(H5F_mount);
@@ -2975,8 +2996,11 @@ H5F_mount(H5G_entry_t *loc, const char *name, H5F_t *child,
 
     /* Search the open IDs and replace names for mount operation */
     /* We pass H5G_UNKNOWN as object type; search all IDs */
-    if (H5G_replace_name( H5G_UNKNOWN, loc, name, NULL, NULL, NULL, OP_MOUNT )<0)
+    name_r=H5RS_wrap(name);
+    assert(name_r);
+    if (H5G_replace_name( H5G_UNKNOWN, loc, name_r, NULL, NULL, NULL, OP_MOUNT )<0)
 	HGOTO_ERROR(H5E_FILE, H5E_MOUNT, FAIL, "unable to replace name");
+    H5RS_decr(name_r);
 
 done:
     if (ret_value<0 && mount_point)
@@ -3050,7 +3074,7 @@ H5F_unmount(H5G_entry_t *loc, const char *name)
 	for (i=0; i<parent->mtab.nmounts; i++) {
 	    if (parent->mtab.child[i].file==child) {
                 /* Search the open IDs replace names to reflect unmount operation */
-                if (H5G_replace_name( H5G_UNKNOWN, mnt_ent, mnt_ent->user_path, NULL, NULL, NULL, OP_UNMOUNT )<0)
+                if (H5G_replace_name( H5G_UNKNOWN, mnt_ent, mnt_ent->user_path_r, NULL, NULL, NULL, OP_UNMOUNT )<0)
                     HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to replace name ");
 
 		/* Unmount the child */
@@ -3181,6 +3205,74 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5F_has_mount
+ *
+ * Purpose:	Check if a file has mounted files within it.
+ *
+ * Return:	Success:	TRUE/FALSE
+ *		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, January  2, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5F_has_mount(const H5F_t *file)
+{
+    htri_t ret_value;   /* Return value */
+    
+    FUNC_ENTER_NOAPI(H5F_has_mount, FAIL);
+
+    assert(file);
+
+    if(file->mtab.nmounts>0)
+        ret_value=TRUE;
+    else
+        ret_value=FALSE;
+    
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5F_has_mount() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5F_is_mount
+ *
+ * Purpose:	Check if a file is mounted within another file.
+ *
+ * Return:	Success:	TRUE/FALSE
+ *		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, January  2, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5F_is_mount(const H5F_t *file)
+{
+    htri_t ret_value;   /* Return value */
+    
+    FUNC_ENTER_NOAPI(H5F_is_mount, FAIL);
+
+    assert(file);
+
+    if(file->mtab.parent!=NULL)
+        ret_value=TRUE;
+    else
+        ret_value=FALSE;
+    
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5F_is_mount() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5Fmount
  *
  * Purpose:	Mount file CHILD_ID onto the group specified by LOC_ID and
@@ -3214,8 +3306,9 @@ H5Fmount(hid_t loc_id, const char *name, hid_t child_id, hid_t plist_id)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file");
     if(H5P_DEFAULT == plist_id)
         plist_id = H5P_MOUNT_DEFAULT;
-    if(TRUE != H5P_isa_class(plist_id, H5P_MOUNT))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not property list");
+    else
+        if(TRUE != H5P_isa_class(plist_id, H5P_MOUNT))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not property list");
 
     /* Do the mount */
     if (H5F_mount(loc, name, child, plist_id)<0)
@@ -3307,7 +3400,7 @@ H5Freopen(hid_t file_id)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file");
 
     /* Get a new "top level" file struct, sharing the same "low level" file struct */
-    if (NULL==(new_file=H5F_new(old_file->shared, H5P_DEFAULT, H5P_DEFAULT)))
+    if (NULL==(new_file=H5F_new(old_file->shared, H5P_FILE_CREATE_DEFAULT, H5P_FILE_ACCESS_DEFAULT)))
 	HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to reopen file");
 
     /* Keep old file's read/write intent in new file */
@@ -3373,27 +3466,14 @@ H5F_get_intent(const H5F_t *f)
 size_t
 H5F_sizeof_addr(const H5F_t *f)
 {
-    size_t sizeof_addr = 0;
-    H5P_genplist_t *plist;              /* Property list */
-    size_t      ret_value;              /* Return value */
-
-    FUNC_ENTER_NOAPI(H5F_sizeof_addr, 0);
+    /* Use FUNC_ENTER_NOINIT here to avoid performance issues */
+    FUNC_ENTER_NOINIT(H5F_sizeof_addr);
 
     assert(f);
     assert(f->shared);
 
-    /* Get property list */
-    if(NULL == (plist = H5I_object(f->shared->fcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, UFAIL, "not a property list");
-
-    if(H5P_get(plist, H5F_CRT_ADDR_BYTE_NUM_NAME, &sizeof_addr)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, UFAIL, "can't get byte number for address");
-
-    /* Set return value */
-    ret_value=sizeof_addr;
-
 done:
-    FUNC_LEAVE(ret_value);
+    FUNC_LEAVE(f->shared->sizeof_addr);
 }
 
 
@@ -3419,31 +3499,88 @@ done:
 size_t
 H5F_sizeof_size(const H5F_t *f)
 {
-    size_t   sizeof_size = 0;
-    H5P_genplist_t *plist;              /* Property list */
-    size_t      ret_value;              /* Return value */
-
-    FUNC_ENTER_NOAPI(H5F_sizeof_size, 0);
+    /* Use FUNC_ENTER_NOINIT here to avoid performance issues */
+    FUNC_ENTER_NOINIT(H5F_sizeof_size);
 
     assert(f);
     assert(f->shared);
 
-    /* Get property list */
-    if(NULL == (plist = H5I_object(f->shared->fcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, UFAIL, "not a property list");
+done:
+    FUNC_LEAVE(f->shared->sizeof_size);
+}
 
-    if(H5P_get(plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &sizeof_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, UFAIL, "can't get byte number for object size");
+
+/*-------------------------------------------------------------------------
+ * Function:	H5F_sym_leaf_k
+ *
+ * Purpose:	Replaced a macro to retrieve the symbol table leaf size,
+ *              now that the generic properties are being used to store
+ *              the values.
+ *
+ * Return:	Success:	Non-negative, and the symbol table leaf size is
+ *                              returned.
+ *
+ * 		Failure:	Negative (should not happen)
+ *
+ * Programmer:	Raymond Lu
+ *		slu@ncsa.uiuc.edu
+ *		Oct 14 2001
+ *
+ * Modifications:
+ *		Quincey Koziol, 2001-10-15
+ *		Added this header and removed unused ret_value variable.
+ *-------------------------------------------------------------------------
+ */
+unsigned H5F_sym_leaf_k(const H5F_t *f)
+{
+    /* Use FUNC_ENTER_NOINIT here to avoid performance issues */
+    FUNC_ENTER_NOINIT(H5F_sym_leaf_k);
 
-    /* Set return value */
-    ret_value=sizeof_size;
+    assert(f);
+    assert(f->shared);
 
 done:
-    FUNC_LEAVE(ret_value);
+    FUNC_LEAVE(f->shared->sym_leaf_k);
 }
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5F_Kvalue
+ *
+ * Purpose:	Replaced a macro to retrieve a B-tree key value for a certain
+ *              type, now that the generic properties are being used to store
+ *              the B-tree values.
+ *
+ * Return:	Success:	Non-negative, and the B-tree key value is
+ *                              returned.
+ *
+ * 		Failure:	Negative (should not happen)
+ *
+ * Programmer:	Raymond Lu
+ *		slu@ncsa.uiuc.edu
+ *		Oct 14 2001
+ *
+ * Modifications:
+ *		Quincey Koziol, 2001-10-15
+ *		Added this header and removed unused ret_value variable.
+ *-------------------------------------------------------------------------
+ */
+int
+H5F_Kvalue(const H5F_t *f, const H5B_class_t *type)
+{
+    /* Use FUNC_ENTER_NOINIT here to avoid performance issues */
+    FUNC_ENTER_NOINIT(H5F_Kvalue);
+
+    assert(f);
+    assert(f->shared);
+    assert(type);
+
+done:
+    FUNC_LEAVE(f->shared->btree_k[type->id]);
+} /* end H5F_Kvalue() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5F_get_driver_id
  *
  * Purpose:	Quick and dirty routine to retrieve the file's 'driver_id' value
@@ -3509,23 +3646,35 @@ done:
     FUNC_LEAVE(ret_value);
 } /* end H5F_get_fileno() */
 
-
+
+/*-------------------------------------------------------------------------
+ * Function:	H5F_get_base_addr
+ *
+ * Purpose:	Quick and dirty routine to retrieve the file's 'base_addr' value
+ *          (Mainly added to stop non-file routines from poking about in the
+ *          H5F_t data structure)
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Raymond Lu <slu@ncsa.uiuc.edu>
+ *		December 20, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
 haddr_t 
 H5F_get_base_addr(const H5F_t *f)
 {
-    haddr_t	ret_value;
-
-    FUNC_ENTER_NOAPI(H5F_get_base_addr, FAIL);
+    /* Use FUNC_ENTER_NOINIT here to avoid performance issues */
+    FUNC_ENTER_NOINIT(H5F_get_base_addr);
 
     assert(f);
     assert(f->shared);
 
-    /* Retrieve the file's base address */
-    ret_value = f->shared->base_addr;
-
 done:
-    FUNC_LEAVE(ret_value);
-}
+    FUNC_LEAVE(f->shared->base_addr);
+} /* end H5F_get_bass_addr() */
 
 
 /*-------------------------------------------------------------------------
@@ -3800,9 +3949,6 @@ H5F_debug(H5F_t *f, haddr_t UNUSED addr, FILE * stream, int indent,
 	  int fwidth)
 {
     hsize_t userblock_size;
-    int     btree_k[H5B_NUM_BTREE_ID];
-    unsigned sym_leaf_k;
-    size_t  sizeof_addr, sizeof_size;
     int     boot_vers, freespace_vers, obj_dir_vers, share_head_vers;
     H5P_genplist_t *plist;              /* Property list */
     herr_t      ret_value=SUCCEED;       /* Return value */
@@ -3822,15 +3968,6 @@ H5F_debug(H5F_t *f, haddr_t UNUSED addr, FILE * stream, int indent,
 
     if(H5P_get(plist, H5F_CRT_USER_BLOCK_NAME, &userblock_size)<0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get user block size");
-    if(H5P_get(plist, H5F_CRT_SYM_LEAF_NAME, &sym_leaf_k)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get rank for symbol table leaf nodes");
-    if(H5P_get(plist, H5F_CRT_BTREE_RANK_NAME, btree_k)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get rank for btree nodes");
-
-    if(H5P_get(plist, H5F_CRT_ADDR_BYTE_NUM_NAME, &sizeof_addr)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get byte number for an address");
-    if(H5P_get(plist, H5F_CRT_OBJ_BYTE_NUM_NAME, &sizeof_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get byte number for object size");
 
     if(H5P_get(plist, H5F_CRT_BOOT_VERS_NAME, &boot_vers)<0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get boot block version");
@@ -3868,14 +4005,14 @@ H5F_debug(H5F_t *f, haddr_t UNUSED addr, FILE * stream, int indent,
     HDfprintf(stream, "%*s%-*s %lu bytes\n", indent, "", fwidth,
 	      "Size of user block:", (unsigned long) userblock_size);
     HDfprintf(stream, "%*s%-*s %u bytes\n", indent, "", fwidth,
-	      "Size of file size_t type:", (unsigned) sizeof_size);
+	      "Size of file size_t type:", (unsigned) f->shared->sizeof_size);
     HDfprintf(stream, "%*s%-*s %u bytes\n", indent, "", fwidth,
-	      "Size of file haddr_t type:", (unsigned) sizeof_addr);
+	      "Size of file haddr_t type:", (unsigned) f->shared->sizeof_addr);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
-	      "Symbol table leaf node 1/2 rank:", sym_leaf_k);
+	      "Symbol table leaf node 1/2 rank:", f->shared->sym_leaf_k);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
 	      "Symbol table internal node 1/2 rank:",
-              (unsigned) (btree_k[H5B_SNODE_ID]));
+              (unsigned) (f->shared->btree_k[H5B_SNODE_ID]));
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
 	      "Boot block version number:", (unsigned) boot_vers);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
diff --git a/src/H5FD.c b/src/H5FD.c
index 60ab418..70098ce 100644
--- a/src/H5FD.c
+++ b/src/H5FD.c
@@ -513,7 +513,7 @@ H5FD_fapl_copy(hid_t driver_id, const void *old_fapl)
     FUNC_ENTER_NOAPI(H5FD_fapl_copy, NULL);
 
     /* Check args */
-    if (NULL==(driver=H5I_object_verify(driver_id,H5I_VFL)))
+    if (NULL==(driver=H5I_object(driver_id)))
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a driver ID");
     if (!old_fapl)
         HGOTO_DONE(NULL); /*but no error*/
@@ -560,7 +560,7 @@ H5FD_fapl_free(hid_t driver_id, void *fapl)
     FUNC_ENTER_NOAPI(H5FD_fapl_free, FAIL);
 
     /* Check args */
-    if (NULL==(driver=H5I_object_verify(driver_id,H5I_VFL)))
+    if (NULL==(driver=H5I_object(driver_id)))
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a driver ID");
     
     /* Allow driver to free or do it ourselves */
@@ -606,7 +606,7 @@ H5FD_dxpl_copy(hid_t driver_id, const void *old_dxpl)
     FUNC_ENTER_NOAPI(H5FD_dxpl_copy, NULL);
 
     /* Check args */
-    if (NULL==(driver=H5I_object_verify(driver_id,H5I_VFL)))
+    if (NULL==(driver=H5I_object(driver_id)))
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a driver ID");
     if (!old_dxpl)
         HGOTO_DONE(NULL); /*but no error*/
@@ -653,7 +653,7 @@ H5FD_dxpl_free(hid_t driver_id, void *dxpl)
     FUNC_ENTER_NOAPI(H5FD_dxpl_free, FAIL);
 
     /* Check args */
-    if (NULL==(driver=H5I_object_verify(driver_id,H5I_VFL)))
+    if (NULL==(driver=H5I_object(driver_id)))
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a driver ID");
     
     /* Allow driver to free or do it ourselves */
@@ -731,6 +731,13 @@ H5FDopen(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
 
     FUNC_ENTER_API(H5FDopen, NULL);
 
+    /* Check arguments */
+    if(H5P_DEFAULT == fapl_id)
+        fapl_id = H5P_FILE_ACCESS_DEFAULT;
+    else
+        if (TRUE!=H5P_isa_class(fapl_id,H5P_FILE_ACCESS))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
+
     if (NULL==(ret_value=H5FD_open(name, flags, fapl_id, maxaddr)))
 	HGOTO_ERROR(H5E_VFL, H5E_CANTINIT, NULL, "unable to open file");
 
@@ -773,10 +780,8 @@ H5FD_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
     
     FUNC_ENTER_NOAPI(H5FD_open, NULL);
 
-    /* Check arguments */
-    if(H5P_DEFAULT == fapl_id)
-        fapl_id = H5P_FILE_ACCESS_DEFAULT;
-    if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
+    /* Get file access property list */
+    if(NULL == (plist = H5I_object(fapl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list"); 
  
     if (0==maxaddr)
@@ -786,7 +791,7 @@ H5FD_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, NULL, "can't get driver ID");
 
     /* Get driver info */
-    if (NULL==(driver=H5I_object_verify(driver_id,H5I_VFL)))
+    if (NULL==(driver=H5I_object(driver_id)))
 	HGOTO_ERROR(H5E_VFL, H5E_BADVALUE, NULL, "invalid driver ID in file access property list");
     if (NULL==driver->open)
 	HGOTO_ERROR(H5E_VFL, H5E_UNSUPPORTED, NULL, "file driver has no `open' method");
@@ -1392,7 +1397,7 @@ H5FD_alloc(H5FD_t *file, H5FD_mem_t type, hsize_t size)
                 else {
 
                     /* Attempt to allocate memory for temporary node */ 
-                    tmp = H5FL_ALLOC(H5FD_free_t,0);
+                    tmp = H5FL_MALLOC(H5FD_free_t);
 #ifdef H5F_DEBUG
                     if (H5DEBUG(F)) {
                         HDfprintf(H5DEBUG(F),
@@ -1807,7 +1812,7 @@ H5FD_free(H5FD_t *file, H5FD_mem_t type, haddr_t addr, hsize_t size)
                     tail_size=(file->accum_loc+file->accum_size)-tail_addr;
 
                     /* Write out the part of the accumulator after the block to free */
-                    if (H5FD_write(file, H5FD_MEM_DEFAULT, H5P_DEFAULT, tail_addr, tail_size, file->meta_accum+(tail_addr-file->accum_loc))<0)
+                    if (H5FD_write(file, H5FD_MEM_DEFAULT, H5P_DATASET_XFER_DEFAULT, tail_addr, tail_size, file->meta_accum+(tail_addr-file->accum_loc))<0)
                         HGOTO_ERROR(H5E_VFL, H5E_WRITEERROR, FAIL, "file write request failed");
                 } /* end if */
 
@@ -1904,7 +1909,7 @@ H5FD_free(H5FD_t *file, H5FD_mem_t type, haddr_t addr, hsize_t size)
         } /* end if */
         else {
             /* Allocate a new node to hold the free block's information */
-            if(NULL==(last = H5FL_ALLOC(H5FD_free_t,0)))
+            if(NULL==(last = H5FL_MALLOC(H5FD_free_t)))
                 HGOTO_ERROR(H5E_FILE, H5E_NOSPACE, FAIL, "can't allocate node for free space info");
 
             last->addr = addr;
@@ -2336,8 +2341,9 @@ H5FDread(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, size_t size
     /* Get the default dataset transfer property list if the user didn't provide one */
     if (H5P_DEFAULT == dxpl_id)
         dxpl_id= H5P_DATASET_XFER_DEFAULT;
-    if (TRUE!=H5P_isa_class(dxpl_id,H5P_DATASET_XFER))
-	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data transfer property list");
+    else
+        if (TRUE!=H5P_isa_class(dxpl_id,H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data transfer property list");
     if (!buf)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "null result buffer");
 
@@ -2563,8 +2569,9 @@ H5FDwrite(H5FD_t *file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, size_t siz
     /* Get the default dataset transfer property list if the user didn't provide one */
     if (H5P_DEFAULT == dxpl_id)
         dxpl_id= H5P_DATASET_XFER_DEFAULT;
-    if (TRUE!=H5P_isa_class(dxpl_id,H5P_DATASET_XFER))
-	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data transfer property list");
+    else
+        if (TRUE!=H5P_isa_class(dxpl_id,H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data transfer property list");
     if (!buf)
 	HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "null buffer");
 
diff --git a/src/H5FDfamily.c b/src/H5FDfamily.c
index 00a98db..f6ad440 100644
--- a/src/H5FDfamily.c
+++ b/src/H5FDfamily.c
@@ -194,8 +194,11 @@ H5Pset_fapl_family(hid_t fapl_id, hsize_t memb_size, hid_t memb_fapl_id)
     /* Check arguments */
     if(TRUE != H5P_isa_class(fapl_id, H5P_FILE_ACCESS))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access property list");
-    if(memb_fapl_id!=H5P_DEFAULT && TRUE != H5P_isa_class(memb_fapl_id, H5P_FILE_ACCESS))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access list");
+    if(H5P_DEFAULT == memb_fapl_id)
+        memb_fapl_id = H5P_FILE_ACCESS_DEFAULT;
+    else
+        if(TRUE != H5P_isa_class(memb_fapl_id, H5P_FILE_ACCESS))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access list");
 
     /*
      * Initialize driver specific information. No need to copy it into the FA
@@ -345,8 +348,8 @@ H5FD_family_fapl_copy(const void *_old_fa)
     memcpy(new_fa, old_fa, sizeof(H5FD_family_fapl_t));
 
     /* Deep copy the property list objects in the structure */
-    if(old_fa->memb_fapl_id==H5P_DEFAULT)
-        new_fa->memb_fapl_id = H5P_DEFAULT;
+    if(old_fa->memb_fapl_id==H5P_FILE_ACCESS_DEFAULT)
+        H5I_inc_ref(new_fa->memb_fapl_id);
     else {
         if(NULL == (plist = H5I_object(old_fa->memb_fapl_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
@@ -427,9 +430,14 @@ H5FD_family_dxpl_copy(const void *_old_dx)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     memcpy(new_dx, old_dx, sizeof(H5FD_family_dxpl_t));
-    if(NULL == (plist = H5I_object(old_dx->memb_dxpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
-    new_dx->memb_dxpl_id = H5P_copy_plist(plist);
+
+    if(old_dx->memb_dxpl_id==H5P_DATASET_XFER_DEFAULT)
+        H5I_inc_ref(new_dx->memb_dxpl_id);
+    else {
+        if(NULL == (plist = H5I_object(old_dx->memb_dxpl_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
+        new_dx->memb_dxpl_id = H5P_copy_plist(plist);
+    } /* end else */
 
     /* Set return value */
     ret_value=new_dx;
@@ -515,8 +523,9 @@ H5FD_family_open(const char *name, unsigned flags, hid_t fapl_id,
     /* Initialize file from file access properties */
     if (NULL==(file=H5MM_calloc(sizeof(H5FD_family_t))))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "unable to allocate file struct");
-    if (H5P_DEFAULT==fapl_id) {
-        file->memb_fapl_id = H5P_DEFAULT;
+    if (H5P_FILE_ACCESS_DEFAULT==fapl_id) {
+        file->memb_fapl_id = H5P_FILE_ACCESS_DEFAULT;
+        H5I_inc_ref(file->memb_fapl_id);
         file->memb_size = 1024*1024*1024; /*1GB*/
     } else {
         H5FD_family_fapl_t *fa;
@@ -524,8 +533,8 @@ H5FD_family_open(const char *name, unsigned flags, hid_t fapl_id,
         if(NULL == (plist = H5I_object(fapl_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
         fa = H5P_get_driver_info(plist);
-        if(fa->memb_fapl_id==H5P_DEFAULT)
-            file->memb_fapl_id = H5P_DEFAULT;
+        if(fa->memb_fapl_id==H5P_FILE_ACCESS_DEFAULT)
+            H5I_inc_ref(file->memb_fapl_id);
         else {
             if(NULL == (plist = H5I_object(fa->memb_fapl_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
@@ -920,8 +929,6 @@ H5FD_family_get_handle(H5FD_t *_file, hid_t fapl, void** file_handle)
     FUNC_ENTER_NOAPI(H5FD_family_get_handle, FAIL);
 
     /* Get the plist structure and family offset */
-    if(H5P_DEFAULT == fapl)
-        fapl = H5Pcreate(H5P_FILE_ACCESS);
     if(NULL == (plist = H5P_object_verify(fapl, H5P_FILE_ACCESS)))
         HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
     if(H5P_get(plist, H5F_ACS_FAMILY_OFFSET_NAME, &offset) < 0)
@@ -963,7 +970,7 @@ H5FD_family_read(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, si
 {
     H5FD_family_t	*file = (H5FD_family_t*)_file;
     unsigned char	*buf = (unsigned char*)_buf;
-    hid_t		memb_dxpl_id = H5P_DEFAULT;
+    hid_t		memb_dxpl_id = H5P_DATASET_XFER_DEFAULT;
     int			i;
     haddr_t		sub;
     size_t		req;
@@ -979,7 +986,7 @@ H5FD_family_read(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, si
      */
     if(NULL == (plist = H5I_object(dxpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access property list");
-    if (H5P_DEFAULT!=dxpl_id && H5FD_FAMILY==H5P_get_driver(plist)) {
+    if (H5P_DATASET_XFER_DEFAULT!=dxpl_id && H5FD_FAMILY==H5P_get_driver(plist)) {
         H5FD_family_dxpl_t *dx = H5P_get_driver_info(plist);
 
         assert(TRUE==H5P_isa_class(dxpl_id, H5P_DATASET_XFER));
@@ -1040,7 +1047,7 @@ H5FD_family_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, s
 {
     H5FD_family_t	*file = (H5FD_family_t*)_file;
     const unsigned char	*buf = (const unsigned char*)_buf;
-    hid_t		memb_dxpl_id = H5P_DEFAULT;
+    hid_t		memb_dxpl_id = H5P_DATASET_XFER_DEFAULT;
     int			i;
     haddr_t		sub;
     size_t		req;
@@ -1056,7 +1063,7 @@ H5FD_family_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, s
      */
     if(NULL == (plist = H5I_object(dxpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access property list");
-    if (H5P_DEFAULT!=dxpl_id && H5FD_FAMILY==H5P_get_driver(plist)) {
+    if (H5P_DATASET_XFER_DEFAULT!=dxpl_id && H5FD_FAMILY==H5P_get_driver(plist)) {
         H5FD_family_dxpl_t *dx = H5P_get_driver_info(plist);
 
         assert(TRUE==H5P_isa_class(dxpl_id, H5P_DATASET_XFER));
diff --git a/src/H5FDgass.c b/src/H5FDgass.c
index 1f01240..4b42b27 100644
--- a/src/H5FDgass.c
+++ b/src/H5FDgass.c
@@ -17,15 +17,11 @@
 #include "H5MMprivate.h"        /* Memory allocation */
 #include "H5Pprivate.h"		/*property lists			*/
 
-
-#undef MAX
-#define MAX(X,Y)	((X)>(Y)?(X):(Y))
+#ifdef H5_HAVE_GASS
 
 /* The driver identification number, initialized at runtime */
 static hid_t H5FD_GASS_g = 0;
 
-#ifdef H5_HAVE_GASS
-
 /* File operations */
 #define OP_UNKNOWN	0
 #define OP_READ		1
@@ -363,7 +359,7 @@ H5FD_gass_open(const char *name, unsigned flags, hid_t fapl_id,
     /* Obtain a pointer to gass-specific file access properties */
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
-    if (H5P_DEFAULT==fapl_id || H5FD_GASS!=H5P_get_driver(plist)) {
+    if (H5P_FILE_ACCESS_DEFAULT==fapl_id || H5FD_GASS!=H5P_get_driver(plist)) {
         GASS_INFO_NULL (_fa.info);
         /* _fa.info = GASS_INFO_NULL; */
         /* _fa.info = {0,0}; */ /*default*/
diff --git a/src/H5FDlog.c b/src/H5FDlog.c
index 5e81260..f42da62 100644
--- a/src/H5FDlog.c
+++ b/src/H5FDlog.c
@@ -39,7 +39,7 @@ static hid_t H5FD_LOG_g = 0;
 
 /* Driver-specific file access properties */
 typedef struct H5FD_log_fapl_t {
-    char *logfile;		/* Allocated log file name */
+    char *logfile;	        /* Allocated log file name */
     unsigned flags;             /* Flags for logging behavior */
     size_t buf_size;            /* Size of buffers for track flavor and number of times each byte is accessed */
 } H5FD_log_fapl_t;
@@ -283,7 +283,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5Pset_fapl_log(hid_t fapl_id, char *logfile, int verbosity)
+H5Pset_fapl_log(hid_t fapl_id, const char *logfile, int verbosity)
 {
     H5FD_log_fapl_t	fa;     /* File access property list information */
     H5P_genplist_t *plist;      /* Property list pointer */
@@ -330,7 +330,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5Pset_fapl_log(hid_t fapl_id, char *logfile, unsigned flags, size_t buf_size)
+H5Pset_fapl_log(hid_t fapl_id, const char *logfile, unsigned flags, size_t buf_size)
 {
     H5FD_log_fapl_t	fa;     /* File access property list information */
     H5P_genplist_t *plist;      /* Property list pointer */
diff --git a/src/H5FDlog.h b/src/H5FDlog.h
index adb4e0a..3a4bfc9 100644
--- a/src/H5FDlog.h
+++ b/src/H5FDlog.h
@@ -48,9 +48,9 @@ extern "C" {
 
 H5_DLL hid_t H5FD_log_init(void);
 #ifdef H5_WANT_H5_V1_4_COMPAT
-H5_DLL herr_t H5Pset_fapl_log(hid_t fapl_id, char *logfile, int verbosity);
+H5_DLL herr_t H5Pset_fapl_log(hid_t fapl_id, const char *logfile, int verbosity);
 #else /* H5_WANT_H5_V1_4_COMPAT */
-H5_DLL herr_t H5Pset_fapl_log(hid_t fapl_id, char *logfile, unsigned flags, size_t buf_size);
+H5_DLL herr_t H5Pset_fapl_log(hid_t fapl_id, const char *logfile, unsigned flags, size_t buf_size);
 #endif /* H5_WANT_H5_V1_4_COMPAT */
 
 #ifdef __cplusplus
diff --git a/src/H5FDmpio.c b/src/H5FDmpio.c
index 73a66db..0a483f0 100644
--- a/src/H5FDmpio.c
+++ b/src/H5FDmpio.c
@@ -25,6 +25,8 @@
 #include "H5MMprivate.h"        /* Memory allocation */
 #include "H5Pprivate.h"		/*property lists			*/
 
+#ifdef H5_HAVE_PARALLEL
+
 /*
  * The driver identification number, initialized at runtime if H5_HAVE_PARALLEL
  * is defined. This allows applications to still have the H5FD_MPIO
@@ -33,8 +35,6 @@
  */
 static hid_t H5FD_MPIO_g = 0;
 
-#ifdef H5_HAVE_PARALLEL
-
 /*
  * The description of a file belonging to this driver.
  * The EOF value is only used just after the file is opened in order for the
@@ -255,6 +255,9 @@ H5Pset_fapl_mpio(hid_t fapl_id, MPI_Comm comm, MPI_Info info)
     FUNC_ENTER_API(H5Pset_fapl_mpio, FAIL);
     H5TRACE3("e","iMcMi",fapl_id,comm,info);
 
+    if(fapl_id==H5P_DEFAULT)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list");
+
     /* Check arguments */
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a file access list");
@@ -370,6 +373,9 @@ H5Pset_dxpl_mpio(hid_t dxpl_id, H5FD_mpio_xfer_t xfer_mode)
     FUNC_ENTER_API(H5Pset_dxpl_mpio, FAIL);
     H5TRACE2("e","iDt",dxpl_id,xfer_mode);
     
+    if(dxpl_id==H5P_DEFAULT)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't set values in default property list");
+
     /* Check arguments */
     if(NULL == (plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_PLIST, H5E_BADTYPE, FAIL, "not a dxpl");
@@ -848,7 +854,7 @@ H5FD_mpio_open(const char *name, unsigned flags, hid_t fapl_id,
     /* Obtain a pointer to mpio-specific file access properties */
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
-    if (H5P_DEFAULT==fapl_id || H5FD_MPIO!=H5P_get_driver(plist)) {
+    if (H5P_FILE_ACCESS_DEFAULT==fapl_id || H5FD_MPIO!=H5P_get_driver(plist)) {
 	_fa.comm = MPI_COMM_SELF; /*default*/
 	_fa.info = MPI_INFO_NULL; /*default*/
 	fa = &_fa;
diff --git a/src/H5FDmpiposix.c b/src/H5FDmpiposix.c
index 63b445b..f1a2768 100644
--- a/src/H5FDmpiposix.c
+++ b/src/H5FDmpiposix.c
@@ -53,6 +53,8 @@
 #   include <gpfs_fcntl.h>
 #endif
 
+#ifdef H5_HAVE_PARALLEL
+
 /*
  * The driver identification number, initialized at runtime if H5_HAVE_PARALLEL
  * is defined. This allows applications to still have the H5FD_MPIPOSIX
@@ -61,8 +63,6 @@
  */
 static hid_t H5FD_MPIPOSIX_g = 0;
 
-#ifdef H5_HAVE_PARALLEL
-
 /* File operations */
 #define OP_UNKNOWN	0
 #define OP_READ		1
@@ -569,7 +569,7 @@ H5FD_mpiposix_open(const char *name, unsigned flags, hid_t fapl_id,
     /* Obtain a pointer to mpiposix-specific file access properties */
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
-    if (H5P_DEFAULT==fapl_id || H5FD_MPIPOSIX!=H5P_get_driver(plist)) {
+    if (H5P_FILE_ACCESS_DEFAULT==fapl_id || H5FD_MPIPOSIX!=H5P_get_driver(plist)) {
 	_fa.comm = MPI_COMM_SELF; /*default*/
 	fa = &_fa;
     } /* end if */
diff --git a/src/H5FDmulti.c b/src/H5FDmulti.c
index 9a9667e..45ee689 100644
--- a/src/H5FDmulti.c
+++ b/src/H5FDmulti.c
@@ -417,7 +417,7 @@ H5Pset_fapl_multi(hid_t fapl_id, const H5FD_mem_t *memb_map,
     }
     if (!memb_fapl) {
 	for (mt=H5FD_MEM_DEFAULT; mt<H5FD_MEM_NTYPES; mt=(H5FD_mem_t)(mt+1)) {
-	    _memb_fapl[mt] = H5P_DEFAULT;
+	    _memb_fapl[mt] = H5Pcreate(H5P_FILE_ACCESS);
 	}
 	memb_fapl = _memb_fapl;
     }
@@ -464,6 +464,12 @@ H5Pset_fapl_multi(hid_t fapl_id, const H5FD_mem_t *memb_map,
     memcpy(fa.memb_name, memb_name, H5FD_MEM_NTYPES*sizeof(char*));
     memcpy(fa.memb_addr, memb_addr, H5FD_MEM_NTYPES*sizeof(haddr_t));
     fa.relax = relax;
+
+    /* Patch up H5P_DEFAULT property lists for members */
+    for (mt=H5FD_MEM_DEFAULT; mt<H5FD_MEM_NTYPES; mt=(H5FD_mem_t)(mt+1)) {
+        if(fa.memb_fapl[mt]==H5P_DEFAULT)
+            fa.memb_fapl[mt] = H5Pcreate(H5P_FILE_ACCESS);
+    }
     return H5Pset_driver(fapl_id, H5FD_MULTI, &fa);
 }
 
@@ -581,13 +587,19 @@ H5Pset_dxpl_multi(hid_t dxpl_id, const hid_t *memb_dxpl)
     if (!memb_dxpl)
         H5Epush_ret(func, H5E_INTERNAL, H5E_BADVALUE, "invalid pointer", -1);
     for (mt=H5FD_MEM_DEFAULT; mt<H5FD_MEM_NTYPES; mt=(H5FD_mem_t)(mt+1)) {
-	if (H5P_DEFAULT!=memb_dxpl[mt] &&
-            TRUE!=H5Pisa_class(memb_dxpl[mt], H5P_DATASET_XFER))
+        if (memb_dxpl[mt]!=H5P_DEFAULT && TRUE!=H5Pisa_class(memb_dxpl[mt], H5P_DATASET_XFER))
             H5Epush_ret(func, H5E_PLIST, H5E_BADTYPE, "not a data transfer property list", -1);
     }
 
     /* Initialize the data transfer property list */
     memcpy(dx.memb_dxpl, memb_dxpl, H5FD_MEM_NTYPES*sizeof(hid_t));
+
+    /* Convert "generic" default property lists into default dataset transfer property lists */
+    for (mt=H5FD_MEM_DEFAULT; mt<H5FD_MEM_NTYPES; mt=(H5FD_mem_t)(mt+1)) {
+        if (dx.memb_dxpl[mt]==H5P_DEFAULT)
+            dx.memb_dxpl[mt]=H5P_DATASET_XFER_DEFAULT;
+    }
+
     return H5Pset_driver(dxpl_id, H5FD_MULTI, &dx);
 }
 
@@ -1173,7 +1185,7 @@ H5FD_multi_open(const char *name, unsigned flags, hid_t fapl_id,
      */
     if (NULL==(file=calloc(1, sizeof(H5FD_multi_t))))
         H5Epush_ret(func, H5E_RESOURCE, H5E_NOSPACE, "memory allocation failed", NULL);
-    if (H5P_DEFAULT==fapl_id || H5FD_MULTI!=H5Pget_driver(fapl_id)) {
+    if (H5P_FILE_ACCESS_DEFAULT==fapl_id || H5FD_MULTI!=H5Pget_driver(fapl_id)) {
         close_fapl = fapl_id = H5Pcreate(H5P_FILE_ACCESS);
         H5Pset_fapl_multi(fapl_id, NULL, NULL, NULL, NULL, TRUE);
     }
@@ -1652,7 +1664,7 @@ H5FD_multi_read(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, siz
     H5Eclear();
 
     /* Get the data transfer properties */
-    if (H5P_DEFAULT!=dxpl_id && H5FD_MULTI==H5Pget_driver(dxpl_id)) {
+    if (H5P_FILE_ACCESS_DEFAULT!=dxpl_id && H5FD_MULTI==H5Pget_driver(dxpl_id)) {
 	dx = H5Pget_driver_info(dxpl_id);
     }
     
@@ -1707,7 +1719,7 @@ H5FD_multi_write(H5FD_t *_file, H5FD_mem_t type, hid_t dxpl_id, haddr_t addr, si
     H5Eclear();
 
     /* Get the data transfer properties */
-    if (H5P_DEFAULT!=dxpl_id && H5FD_MULTI==H5Pget_driver(dxpl_id)) {
+    if (H5P_FILE_ACCESS_DEFAULT!=dxpl_id && H5FD_MULTI==H5Pget_driver(dxpl_id)) {
 	dx = H5Pget_driver_info(dxpl_id);
     }
     
diff --git a/src/H5FDsec2.c b/src/H5FDsec2.c
index f65bcbe..526f539 100644
--- a/src/H5FDsec2.c
+++ b/src/H5FDsec2.c
@@ -310,7 +310,7 @@ H5FD_sec2_open(const char *name, unsigned flags, hid_t UNUSED fapl_id,
         HGOTO_ERROR(H5E_FILE, H5E_BADFILE, NULL, "unable to fstat file");
 
     /* Create the new file struct */
-    if (NULL==(file=H5FL_ALLOC(H5FD_sec2_t,1)))
+    if (NULL==(file=H5FL_CALLOC(H5FD_sec2_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "unable to allocate file struct");
 
     file->fd = fd;
diff --git a/src/H5FDsrb.c b/src/H5FDsrb.c
index bd44382..f2d87c8 100644
--- a/src/H5FDsrb.c
+++ b/src/H5FDsrb.c
@@ -17,11 +17,10 @@
 #include "H5Pprivate.h"		/*property lists			*/
 
 
-/* The driver identification number, initialized at runtime */
-static hid_t H5FD_SRB_g = 0;
-
 #ifdef H5_HAVE_SRB
 
+/* The driver identification number, initialized at runtime */
+static hid_t H5FD_SRB_g = 0;
 
 /*
  * This driver supports systems that have the lseek64() function by defining
@@ -320,7 +319,7 @@ H5FD_srb_open(const char *name, unsigned flags, hid_t fapl_id, haddr_t maxaddr)
 
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
-    if(H5P_DEFAULT==fapl_id || H5FD_SRB!=H5P_get_driver(plist)) {
+    if(H5P_FILE_ACCESS_DEFAULT==fapl_id || H5FD_SRB!=H5P_get_driver(plist)) {
         HDmemset((void*)&_fa, 0, sizeof(H5FD_srb_fapl_t));        
         fa = &_fa;
     }
diff --git a/src/H5FDstream.c b/src/H5FDstream.c
index ee3ca99..a5c89bf 100644
--- a/src/H5FDstream.c
+++ b/src/H5FDstream.c
@@ -594,7 +594,7 @@ H5FD_stream_open (const char *filename,
 #endif
 
   fapl = NULL;
-  if (H5P_DEFAULT != fapl_id) {
+  if (H5P_FILE_ACCESS_DEFAULT != fapl_id) {
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a file access property list");
     fapl = H5P_get_driver_info (plist);
diff --git a/src/H5FL.c b/src/H5FL.c
index 917821c..1e49834 100644
--- a/src/H5FL.c
+++ b/src/H5FL.c
@@ -34,12 +34,12 @@ static int		interface_initialize_g = 0;
     Default limits on how much memory can accumulate on each free list before
     it is garbage collected.
  */
-static size_t H5FL_reg_glb_mem_lim=1*16*65536;/* Default to 1MB limit on all regular free lists */
-static size_t H5FL_reg_lst_mem_lim=1*65536;   /* Default to 64KB limit on each regular free list */
-static size_t H5FL_arr_glb_mem_lim=4*16*65536;/* Default to 4MB limit on all array free lists */
-static size_t H5FL_arr_lst_mem_lim=4*65536;   /* Default to 256KB limit on each array free list */
-static size_t H5FL_blk_glb_mem_lim=16*16*65536; /* Default to 16MB limit on all block free lists */
-static size_t H5FL_blk_lst_mem_lim=16*65536;  /* Default to 1024KB (1MB) limit on each block free list */
+static size_t H5FL_reg_glb_mem_lim=1*1024*1024; /* Default to 1MB limit on all regular free lists */
+static size_t H5FL_reg_lst_mem_lim=1*65536;     /* Default to 64KB limit on each regular free list */
+static size_t H5FL_arr_glb_mem_lim=4*1024*1024; /* Default to 4MB limit on all array free lists */
+static size_t H5FL_arr_lst_mem_lim=4*65536;     /* Default to 256KB limit on each array free list */
+static size_t H5FL_blk_glb_mem_lim=16*1024*1024; /* Default to 16MB limit on all block free lists */
+static size_t H5FL_blk_lst_mem_lim=1024*1024;   /* Default to 1024KB (1MB) limit on each block free list */
 
 /* A garbage collection node for regular free lists */
 typedef struct H5FL_reg_gc_node_t {
@@ -248,7 +248,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FL_reg_alloc
+ * Function:	H5FL_reg_malloc
  *
  * Purpose:	Allocate a block on a free list
  *
@@ -263,11 +263,11 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5FL_reg_alloc(H5FL_reg_head_t *head, unsigned clear)
+H5FL_reg_malloc(H5FL_reg_head_t *head)
 {
     void *ret_value;        /* Pointer to object to return */
 
-    FUNC_ENTER_NOAPI(H5FL_reg_alloc, NULL);
+    FUNC_ENTER_NOAPI(H5FL_reg_malloc, NULL);
 
     /* Double check parameters */
     assert(head);
@@ -301,13 +301,46 @@ H5FL_reg_alloc(H5FL_reg_head_t *head, unsigned clear)
         head->allocated++;
     } /* end else */
 
-    /* Clear to zeros, if asked */
-    if(clear)
-        HDmemset(ret_value,0,head->size);
+done:
+    FUNC_LEAVE (ret_value);
+}   /* end H5FL_reg_malloc() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FL_reg_calloc
+ *
+ * Purpose:	Allocate a block on a free list and clear it to zeros
+ *
+ * Return:	Success:	Pointer to a valid object
+ * 		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Monday, December 23, 2002
+ *
+ * Modifications:
+ * 	
+ *-------------------------------------------------------------------------
+ */
+void *
+H5FL_reg_calloc(H5FL_reg_head_t *head)
+{
+    void *ret_value;        /* Pointer to object to return */
+
+    FUNC_ENTER_NOAPI(H5FL_reg_calloc, NULL);
+
+    /* Double check parameters */
+    assert(head);
+
+    /* Allocate the block */
+    if (NULL==(ret_value = H5FL_reg_malloc(head)))
+        HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+
+    /* Clear to zeros */
+    HDmemset(ret_value,0,head->size);
 
 done:
     FUNC_LEAVE (ret_value);
-}   /* end H5FL_reg_alloc() */
+}   /* end H5FL_reg_calloc() */
 
 
 /*-------------------------------------------------------------------------
@@ -562,7 +595,7 @@ H5FL_blk_create_list(H5FL_blk_node_t **head, size_t size)
     FUNC_ENTER_NOINIT(H5FL_blk_create_list);
 
     /* Allocate room for the new free list node */
-    if(NULL==(temp=H5FL_ALLOC(H5FL_blk_node_t,0)))
+    if(NULL==(temp=H5FL_MALLOC(H5FL_blk_node_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for chunk info");
     
     /* Set the correct values for the new free list */
@@ -632,7 +665,45 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FL_blk_alloc
+ * Function:	H5FL_blk_free_block_avail
+ *
+ * Purpose:	Checks if a free block of the appropriate size is available
+ *      for a given list.
+ *
+ * Return:	Success:	non-negative
+ *		Failure:	negative
+ *
+ * Programmer:	Quincey Koziol
+ *		Monday, December 16, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5FL_blk_free_block_avail(H5FL_blk_head_t *head, size_t size)
+{
+    H5FL_blk_node_t *free_list;  /* The free list of nodes of correct size */
+    htri_t ret_value;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FL_blk_free_block_avail, FAIL);
+
+    /* Double check parameters */
+    assert(head);
+
+    /* check if there is a free list for blocks of this size */
+    /* and if there are any blocks available on the list */
+    if((free_list=H5FL_blk_find_list(&(head->head),size))!=NULL && free_list->list!=NULL)
+        ret_value=TRUE;
+    else
+        ret_value=FALSE;
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5FL_blk_free_block_avail() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FL_blk_malloc
  *
  * Purpose:	Allocates memory for a block.  This routine is used
  *      instead of malloc because the block can be kept on a free list so
@@ -650,13 +721,13 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5FL_blk_alloc(H5FL_blk_head_t *head, size_t size, unsigned clear)
+H5FL_blk_malloc(H5FL_blk_head_t *head, size_t size)
 {
     H5FL_blk_node_t *free_list;  /* The free list of nodes of correct size */
     H5FL_blk_list_t *temp;  /* Temp. ptr to the new native list allocated */
     void *ret_value;    /* Pointer to the block to return to the user */
 
-    FUNC_ENTER_NOAPI(H5FL_blk_alloc, NULL);
+    FUNC_ENTER_NOAPI(H5FL_blk_malloc, NULL);
 
     /* Double check parameters */
     assert(head);
@@ -702,13 +773,50 @@ H5FL_blk_alloc(H5FL_blk_head_t *head, size_t size, unsigned clear)
         ret_value=((char *)temp)+sizeof(H5FL_blk_list_t);
     } /* end else */
 
-    /* Clear the block to zeros, if requested */
-    if(clear)
-        HDmemset(ret_value,0,size);
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5FL_blk_malloc() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FL_blk_calloc
+ *
+ * Purpose:	Allocates memory for a block and clear it to zeros.
+ *      This routine is used
+ *      instead of malloc because the block can be kept on a free list so
+ *      they don't thrash malloc/free as much.
+ *
+ * Return:	Success:	valid pointer to the block
+ *
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *		Monday, December 23, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+void *
+H5FL_blk_calloc(H5FL_blk_head_t *head, size_t size)
+{
+    void *ret_value;    /* Pointer to the block to return to the user */
+
+    FUNC_ENTER_NOAPI(H5FL_blk_calloc, NULL);
+
+    /* Double check parameters */
+    assert(head);
+
+    /* Allocate the block */
+    if (NULL==(ret_value = H5FL_blk_malloc(head,size)))
+        HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+
+    /* Clear the block to zeros */
+    HDmemset(ret_value,0,size);
 
 done:
     FUNC_LEAVE(ret_value);
-} /* end H5FL_blk_alloc() */
+} /* end H5FL_blk_calloc() */
 
 
 /*-------------------------------------------------------------------------
@@ -818,7 +926,7 @@ H5FL_blk_realloc(H5FL_blk_head_t *head, void *block, size_t new_size)
 
         /* check if we are actually changing the size of the buffer */
         if(new_size!=temp->size) {
-            if((ret_value=H5FL_blk_alloc(head,new_size,0))==NULL)
+            if((ret_value=H5FL_blk_malloc(head,new_size))==NULL)
                 HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for block");
             blk_size=MIN(new_size,temp->size);
             HDmemcpy(ret_value,block,blk_size);
@@ -829,7 +937,7 @@ H5FL_blk_realloc(H5FL_blk_head_t *head, void *block, size_t new_size)
     } /* end if */
     /* Not re-allocating, just allocate a fresh block */
     else
-        ret_value=H5FL_blk_alloc(head,new_size,0);
+        ret_value=H5FL_blk_malloc(head,new_size);
 
 done:
     FUNC_LEAVE(ret_value);
@@ -1141,7 +1249,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5FL_arr_alloc
+ * Function:	H5FL_arr_malloc
  *
  * Purpose:	Allocate an array of objects
  *
@@ -1156,13 +1264,13 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5FL_arr_alloc(H5FL_arr_head_t *head, size_t elem, unsigned clear)
+H5FL_arr_malloc(H5FL_arr_head_t *head, size_t elem)
 {
     H5FL_arr_node_t *new_obj;   /* Pointer to the new free list node allocated */
     void *ret_value;        /* Pointer to object to return */
     size_t mem_size;        /* Size of memory block being recycled */
 
-    FUNC_ENTER_NOAPI(H5FL_arr_alloc, NULL);
+    FUNC_ENTER_NOAPI(H5FL_arr_malloc, NULL);
 
     /* Double check parameters */
     assert(head);
@@ -1215,18 +1323,51 @@ H5FL_arr_alloc(H5FL_arr_head_t *head, size_t elem, unsigned clear)
             /* Get a pointer to the new block */
             ret_value=((char *)new_obj)+sizeof(H5FL_arr_node_t);
         } /* end else */
-
-        /* Clear to zeros, if asked */
-        if(clear)
-            HDmemset(ret_value,0,mem_size);
     } /* end if */
     /* No fixed number of elements, use PQ routine */
     else
-        ret_value=H5FL_blk_alloc(&(head->u.queue),mem_size,clear);
+        ret_value=H5FL_blk_malloc(&(head->u.queue),mem_size);
+
+done:
+    FUNC_LEAVE (ret_value);
+}   /* end H5FL_arr_malloc() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5FL_arr_calloc
+ *
+ * Purpose:	Allocate an array of objects and clear it to zeros
+ *
+ * Return:	Success:	Pointer to a valid array object
+ * 		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Monday, December 23, 2002
+ *
+ * Modifications:
+ * 	
+ *-------------------------------------------------------------------------
+ */
+void *
+H5FL_arr_calloc(H5FL_arr_head_t *head, size_t elem)
+{
+    void *ret_value;        /* Pointer to object to return */
+
+    FUNC_ENTER_NOAPI(H5FL_arr_calloc, NULL);
+
+    /* Double check parameters */
+    assert(head);
+
+    /* Allocate the array */
+    if (NULL==(ret_value = H5FL_arr_malloc(head,elem)))
+        HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+
+    /* Clear to zeros */
+    HDmemset(ret_value,0,head->size*elem);
 
 done:
     FUNC_LEAVE (ret_value);
-}   /* end H5FL_arr_alloc() */
+}   /* end H5FL_arr_calloc() */
 
 
 /*-------------------------------------------------------------------------
@@ -1258,7 +1399,7 @@ H5FL_arr_realloc(H5FL_arr_head_t *head, void * obj, size_t new_elem)
 
     /* Check if we are really allocating the object */
     if(obj==NULL) {
-        ret_value=H5FL_arr_alloc(head,new_elem,0);
+        ret_value=H5FL_arr_malloc(head,new_elem);
     } /* end if */
     else {
         /* Check if there is a maximum number of elements in array */
@@ -1272,7 +1413,7 @@ H5FL_arr_realloc(H5FL_arr_head_t *head, void * obj, size_t new_elem)
             /* Check if the size is really changing */
             if(temp->nelem!=new_elem) {
                 /* Get the new array of objects */
-                ret_value=H5FL_arr_alloc(head,new_elem,0);
+                ret_value=H5FL_arr_malloc(head,new_elem);
 
                 /* Copy the appropriate amount of elements */
                 blk_size=head->size*MIN(temp->nelem,new_elem);
diff --git a/src/H5FLprivate.h b/src/H5FLprivate.h
index 35b3555..72e28d8 100644
--- a/src/H5FLprivate.h
+++ b/src/H5FLprivate.h
@@ -66,7 +66,10 @@ typedef struct H5FL_reg_head_t {
 #define H5FL_DEFINE_STATIC(t)  static H5FL_DEFINE(t)
 
 /* Allocate an object of type 't' */
-#define H5FL_ALLOC(t,clr) H5FL_reg_alloc(&(t##_free_list),clr)
+#define H5FL_MALLOC(t) H5FL_reg_malloc(&(t##_free_list))
+
+/* Allocate an object of type 't' and clear it to all zeros */
+#define H5FL_CALLOC(t) H5FL_reg_calloc(&(t##_free_list))
 
 /* Free an object of type 't' */
 #define H5FL_FREE(t,obj) H5FL_reg_free(&(t##_free_list),obj)
@@ -80,7 +83,8 @@ typedef struct H5FL_reg_head_t {
 #define H5FL_DEFINE(t)  int t##_reg_free_list_placeholder
 #define H5FL_EXTERN(t)  extern int t##_reg_free_list_placeholder
 #define H5FL_DEFINE_STATIC(t)  static H5FL_DEFINE(t)
-#define H5FL_ALLOC(t,clr) (clr ? H5MM_calloc(sizeof(t)) : H5MM_malloc(sizeof(t)))
+#define H5FL_MALLOC(t) H5MM_malloc(sizeof(t))
+#define H5FL_CALLOC(t) H5MM_calloc(sizeof(t))
 #define H5FL_FREE(t,obj) H5MM_xfree(obj)
 #endif /* H5_NO_REG_FREE_LISTS */
 
@@ -124,7 +128,10 @@ typedef struct H5FL_blk_head_t {
 #define H5FL_BLK_DEFINE_STATIC(t)  static H5FL_BLK_DEFINE(t)
 
 /* Allocate an block of type 't' */
-#define H5FL_BLK_ALLOC(t,size,clr) H5FL_blk_alloc(&(t##_pq),size,clr)
+#define H5FL_BLK_MALLOC(t,size) H5FL_blk_malloc(&(t##_pq),size)
+
+/* Allocate an block of type 't' and clear it to zeros */
+#define H5FL_BLK_CALLOC(t,size) H5FL_blk_calloc(&(t##_pq),size)
 
 /* Free a block of type 't' */
 #define H5FL_BLK_FREE(t,blk) H5FL_blk_free(&(t##_pq),blk)
@@ -132,13 +139,18 @@ typedef struct H5FL_blk_head_t {
 /* Re-allocate a block of type 't' */
 #define H5FL_BLK_REALLOC(t,blk,new_size) H5FL_blk_realloc(&(t##_pq),blk,new_size)
 
+/* Check if there is a free block available to re-use */
+#define H5FL_BLK_AVAIL(t,size)  H5FL_blk_free_block_avail(&(t##_pq),size)
+
 #else /* H5_NO_BLK_FREE_LISTS */
 #define H5FL_BLK_DEFINE(t)      int t##_blk_free_list_placeholder
 #define H5FL_BLK_EXTERN(t)      extern int t##_blk_free_list_placeholder
 #define H5FL_BLK_DEFINE_STATIC(t)  static H5FL_BLK_DEFINE(t)
-#define H5FL_BLK_ALLOC(t,size,clr) (clr ? H5MM_calloc(size) : H5MM_malloc(size))
+#define H5FL_BLK_MALLOC(t,size) H5MM_malloc(size)
+#define H5FL_BLK_CALLOC(t,size) H5MM_calloc(size)
 #define H5FL_BLK_FREE(t,blk) H5MM_xfree(blk)
 #define H5FL_BLK_REALLOC(t,blk,new_size) H5MM_realloc(blk,new_size)
+#define H5FL_BLK_AVAIL(t,size)  (FALSE)
 #endif /* H5_NO_BLK_FREE_LISTS */
 
 /* Data structure to store each array in free list */
@@ -178,7 +190,10 @@ typedef struct H5FL_arr_head_t {
 #define H5FL_ARR_DEFINE_STATIC(t,m)  static H5FL_ARR_DEFINE(t,m)
 
 /* Allocate an array of type 't' */
-#define H5FL_ARR_ALLOC(t,elem,clr) H5FL_arr_alloc(&(t##_arr_free_list),elem,clr)
+#define H5FL_ARR_MALLOC(t,elem) H5FL_arr_malloc(&(t##_arr_free_list),elem)
+
+/* Allocate an array of type 't' and clear it to all zeros */
+#define H5FL_ARR_CALLOC(t,elem) H5FL_arr_calloc(&(t##_arr_free_list),elem)
 
 /* Free an array of type 't' */
 #define H5FL_ARR_FREE(t,obj) H5FL_arr_free(&(t##_arr_free_list),obj)
@@ -190,7 +205,8 @@ typedef struct H5FL_arr_head_t {
 #define H5FL_ARR_DEFINE(t,m)    int t##_arr_free_list_placeholder
 #define H5FL_ARR_EXTERN(t)      extern int t##_arr_free_list_placeholder
 #define H5FL_ARR_DEFINE_STATIC(t,m)  static H5FL_ARR_DEFINE(t,m)
-#define H5FL_ARR_ALLOC(t,elem,clr) (clr ? H5MM_calloc(elem*sizeof(t)) : H5MM_malloc(elem*sizeof(t)))
+#define H5FL_ARR_MALLOC(t,elem) H5MM_malloc(elem*sizeof(t))
+#define H5FL_ARR_CALLOC(t,elem) H5MM_calloc(elem*sizeof(t))
 #define H5FL_ARR_FREE(t,obj) H5MM_xfree(obj)
 #define H5FL_ARR_REALLOC(t,obj,new_elem) H5MM_realloc(obj,new_elem*sizeof(t))
 #endif /* H5_NO_ARR_FREE_LISTS */
@@ -198,12 +214,16 @@ typedef struct H5FL_arr_head_t {
 /*
  * Library prototypes.
  */
-H5_DLL void * H5FL_blk_alloc(H5FL_blk_head_t *head, size_t size, unsigned clear);
+H5_DLL void * H5FL_blk_malloc(H5FL_blk_head_t *head, size_t size);
+H5_DLL void * H5FL_blk_calloc(H5FL_blk_head_t *head, size_t size);
 H5_DLL void * H5FL_blk_free(H5FL_blk_head_t *head, void *block);
 H5_DLL void * H5FL_blk_realloc(H5FL_blk_head_t *head, void *block, size_t new_size);
-H5_DLL void * H5FL_reg_alloc(H5FL_reg_head_t *head, unsigned clear);
+H5_DLL htri_t H5FL_blk_free_block_avail(H5FL_blk_head_t *head, size_t size);
+H5_DLL void * H5FL_reg_malloc(H5FL_reg_head_t *head);
+H5_DLL void * H5FL_reg_calloc(H5FL_reg_head_t *head);
 H5_DLL void * H5FL_reg_free(H5FL_reg_head_t *head, void *obj);
-H5_DLL void * H5FL_arr_alloc(H5FL_arr_head_t *head, size_t elem, unsigned clear);
+H5_DLL void * H5FL_arr_malloc(H5FL_arr_head_t *head, size_t elem);
+H5_DLL void * H5FL_arr_calloc(H5FL_arr_head_t *head, size_t elem);
 H5_DLL void * H5FL_arr_free(H5FL_arr_head_t *head, void *obj);
 H5_DLL void * H5FL_arr_realloc(H5FL_arr_head_t *head, void *obj, size_t new_elem);
 H5_DLL herr_t H5FL_garbage_coll(void);
diff --git a/src/H5FO.c b/src/H5FO.c
new file mode 100644
index 0000000..29f3998
--- /dev/null
+++ b/src/H5FO.c
@@ -0,0 +1,277 @@
+/****************************************************************************
+ * NCSA HDF								    *
+ * Software Development Group						    *
+ * National Center for Supercomputing Applications			    *
+ * University of Illinois at Urbana-Champaign				    *
+ * 605 E. Springfield, Champaign IL 61820				    *
+ *									    *
+ * For conditions of distribution and use, see the accompanying		    *
+ * hdf/COPYING file.							    *
+ *									    *
+ ****************************************************************************/
+
+/*
+ * Open object info algorithms.
+ *
+ * These are used to track the objects currently open in a file, for various
+ * internal mechanisms which need to be aware of such things.
+ *
+ */
+
+#define H5F_PACKAGE		/*suppress error about including H5Fpkg	  */
+
+#include "H5Eprivate.h"		/* Error handling		  	*/
+#include "H5Fpkg.h"             /* File access                          */
+#include "H5FLprivate.h"	/* Free lists                           */
+#include "H5FOprivate.h"        /* File objects                         */
+
+#define PABLO_MASK	H5FO_mask
+
+/* Interface initialization */
+static int		interface_initialize_g = 0;
+#define INTERFACE_INIT	NULL
+
+/* Private typedefs */
+
+/* Information about object objects in a file */
+typedef struct H5FO_open_obj_t {
+    haddr_t addr;                       /* Address of object header for object */
+                                        /* THIS MUST BE FIRST FOR TBBT ROUTINES */
+    hid_t id;                           /* Current ID for object            */
+} H5FO_open_obj_t;
+
+/* Declare a free list to manage the H5FO_open_obj_t struct */
+H5FL_DEFINE_STATIC(H5FO_open_obj_t);
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5FO_create
+ PURPOSE
+    Create an open object info set
+ USAGE
+    herr_t H5FO_create(f)
+        H5F_t *f;       IN/OUT: File to create opened object info set for
+
+ RETURNS
+    Returns non-negative on success, negative on failure
+ DESCRIPTION
+    Create a new open object info set.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5FO_create(H5F_t *f)
+{
+    herr_t ret_value=SUCCEED;          /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FO_create,FAIL);
+
+    /* Sanity check */
+    assert(f);
+    assert(f->shared);
+
+    /* Create TBBT used to store open object info */
+    if((f->shared->open_objs=H5TB_fast_dmake(H5TB_FAST_HADDR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, FAIL, "unable to create open object TBBT");
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5FO_create() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5FO_opened
+ PURPOSE
+    Checks if an object at an address is already open in the file.
+ USAGE
+    hid_t H5FO_opened(f,addr)
+        const H5F_t *f;         IN: File to check opened object info set
+        haddr_t addr;           IN: Address of object to check
+
+ RETURNS
+    Returns a non-negative ID for the object on success, negative on failure
+ DESCRIPTION
+    Check is an object at an address (the address of the object's object header)
+    is already open in the file and return the ID for that object if it is open.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+hid_t
+H5FO_opened(const H5F_t *f, haddr_t addr)
+{
+    H5TB_NODE *obj_node;        /* TBBT node holding open object */
+    H5FO_open_obj_t *open_obj;  /* Information about open object */
+    hid_t ret_value;            /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FO_opened,FAIL);
+
+    /* Sanity check */
+    assert(f);
+    assert(f->shared);
+    assert(f->shared->open_objs);
+    assert(H5F_addr_defined(addr));
+
+    /* Get the object node from the TBBT */
+    if((obj_node=H5TB_dfind(f->shared->open_objs,&addr,NULL))!=NULL) {
+        open_obj=H5TB_NODE_DATA(obj_node);
+        assert(open_obj);
+        ret_value=open_obj->id;
+        assert(ret_value>0);
+    } /* end if */
+    else
+        ret_value=FAIL;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5FO_opened() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5FO_insert
+ PURPOSE
+    Insert a newly opened object/ID pair into the opened object info set
+ USAGE
+    herr_t H5FO_insert(f,addr,id)
+        H5F_t *f;               IN/OUT: File's opened object info set
+        haddr_t addr;           IN: Address of object to insert
+        hid_t id;               IN: ID of object to insert
+
+ RETURNS
+    Returns a non-negative on success, negative on failure
+ DESCRIPTION
+    Insert an object/ID pair into the opened object info set.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5FO_insert(H5F_t *f, haddr_t addr, hid_t id)
+{
+    H5FO_open_obj_t *open_obj;  /* Information about open object */
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FO_insert,FAIL);
+
+    /* Sanity check */
+    assert(f);
+    assert(f->shared);
+    assert(f->shared->open_objs);
+    assert(H5F_addr_defined(addr));
+    assert(id>0);
+
+    /* Allocate new opened object information structure */
+    if((open_obj=H5FL_MALLOC(H5FO_open_obj_t))==NULL)
+        HGOTO_ERROR(H5E_CACHE,H5E_NOSPACE,NULL,"memory allocation failed");
+
+    /* Assign information */
+    open_obj->addr=addr;
+    open_obj->id=id;
+
+    /* Insert into TBBT */
+    if(H5TB_dins(f->shared->open_objs,open_obj,open_obj)==NULL)
+        HGOTO_ERROR(H5E_CACHE,H5E_CANTINSERT,FAIL,"can't insert object into TBBT");
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5FO_insert() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5FO_delete
+ PURPOSE
+    Remove an opened object/ID pair from the opened object info set
+ USAGE
+    herr_t H5FO_delete(f,addr)
+        H5F_t *f;               IN/OUT: File's opened object info set
+        haddr_t addr;           IN: Address of object to remove
+
+ RETURNS
+    Returns a non-negative on success, negative on failure
+ DESCRIPTION
+    Remove an object/ID pair from the opened object info.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5FO_delete(H5F_t *f, haddr_t addr)
+{
+    H5TB_NODE *obj_node;        /* TBBT node holding open object */
+    H5FO_open_obj_t *open_obj;  /* Information about open object */
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FO_delete,FAIL);
+
+    /* Sanity check */
+    assert(f);
+    assert(f->shared);
+    assert(f->shared->open_objs);
+    assert(H5F_addr_defined(addr));
+
+    /* Get the object node from the TBBT */
+    if((obj_node=H5TB_dfind(f->shared->open_objs,&addr,NULL))==NULL)
+        HGOTO_ERROR(H5E_CACHE,H5E_NOTFOUND,FAIL,"can't locate object in TBBT");
+
+    /* Remove from TBBT */
+    if((open_obj=H5TB_rem(&f->shared->open_objs->root,obj_node,NULL))==NULL)
+        HGOTO_ERROR(H5E_CACHE,H5E_CANTRELEASE,FAIL,"can't remove object from TBBT");
+
+    /* Release the object information */
+    H5FL_FREE(H5FO_open_obj_t,open_obj);
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5FO_delete() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5FO_dest
+ PURPOSE
+    Destroy an open object info set
+ USAGE
+    herr_t H5FO_create(f)
+        H5F_t *f;               IN/OUT: File's opened object info set
+
+ RETURNS
+    Returns a non-negative on success, negative on failure
+ DESCRIPTION
+    Destroy an existing open object info set.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5FO_dest(H5F_t *f)
+{
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5FO_dest,FAIL);
+
+    /* Sanity check */
+    assert(f);
+    assert(f->shared);
+    assert(f->shared->open_objs);
+
+    /* Check if the object info set is empty */
+    if(H5TB_count(f->shared->open_objs)!=0)
+        HGOTO_ERROR(H5E_CACHE, H5E_CANTRELEASE, FAIL, "objects still in open object info set");
+
+    /* Release the open object info set TBBT */
+    f->shared->open_objs=H5TB_dfree(f->shared->open_objs,NULL,NULL);
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5FO_dest() */
+
diff --git a/src/H5FOprivate.h b/src/H5FOprivate.h
new file mode 100644
index 0000000..6f89ec2
--- /dev/null
+++ b/src/H5FOprivate.h
@@ -0,0 +1,42 @@
+/****************************************************************************
+ * NCSA HDF								    *
+ * Software Development Group						    *
+ * National Center for Supercomputing Applications			    *
+ * University of Illinois at Urbana-Champaign				    *
+ * 605 E. Springfield, Champaign IL 61820				    *
+ *									    *
+ * For conditions of distribution and use, see the accompanying		    *
+ * hdf/COPYING file.							    *
+ *									    *
+ ****************************************************************************/
+
+/*
+ * This file contains library private information about the H5FO module
+ */
+#ifndef _H5FOprivate_H
+#define _H5FOprivate_H
+
+#ifdef LATER
+#include "H5FOpublic.h"
+#endif /* LATER */
+
+/* Private headers needed by this file */
+#include "H5private.h"
+#include "H5TBprivate.h"	/* TBBTs	  		        */
+
+/* Typedefs */
+
+/* Typedef for open object cache */
+typedef H5TB_TREE H5FO_t;       /* Currently, all open objects are stored in TBBT */
+
+/* Macros */
+
+/* Private routines */
+H5_DLL herr_t H5FO_create(H5F_t *f);
+H5_DLL hid_t H5FO_opened(const H5F_t *f, haddr_t addr);
+H5_DLL herr_t H5FO_insert(H5F_t *f, haddr_t addr, hid_t id);
+H5_DLL herr_t H5FO_delete(H5F_t *f, haddr_t addr);
+H5_DLL herr_t H5FO_dest(H5F_t *f);
+
+#endif /* _H5FOprivate_H */
+
diff --git a/src/H5FPclient.c b/src/H5FPclient.c
index cae4c60..7912b4e 100644
--- a/src/H5FPclient.c
+++ b/src/H5FPclient.c
@@ -583,6 +583,7 @@ H5FP_update_file_cache(hid_t file_id, struct SAP_sync *sap_sync, uint8_t *msg)
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, FAIL, "unable to open group");
 
     switch (sap_sync->action) {
+#ifdef OLD_WAY
     case H5FP_ACT_CREATE:
         if (sap_sync->obj_type == H5FP_OBJ_DATASET) {
             H5O_efl_t efl;
@@ -598,7 +599,7 @@ H5FP_update_file_cache(hid_t file_id, struct SAP_sync *sap_sync, uint8_t *msg)
                                       fmeta->sdim->size, fmeta->sdim->max) < 0)
                 HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "can't set dimensions");
 
-            if (H5D_update_entry_cache(file, ent, H5G_entof(grp),
+            if (H5D_update_entry_info(file, ent, H5G_entof(grp),
                                        fmeta->dset->s, space,
                                        fmeta->plist, fmeta->layout, fmeta->dtype,
                                        FALSE, fmeta->header) == FAIL)
@@ -607,7 +608,7 @@ H5FP_update_file_cache(hid_t file_id, struct SAP_sync *sap_sync, uint8_t *msg)
             if (H5P_get(fmeta->plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
                 HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get external file list");
 
-            if (H5D_update_external_storage_cache(file, ent, &efl, fmeta->layout) == FAIL)
+            if (H5D_update_external_storage_info(file, ent, &efl, fmeta->layout) == FAIL)
                 HGOTO_ERROR(H5E_FPHDF5, H5E_CANTINIT, FAIL,
                             "can't update external file layout metadata cache");
         }
@@ -624,6 +625,7 @@ H5FP_update_file_cache(hid_t file_id, struct SAP_sync *sap_sync, uint8_t *msg)
         }
 
         break;
+#endif /* OLD_WAY */
 
     case H5FP_ACT_DELETE:
     default:
diff --git a/src/H5Fcontig.c b/src/H5Fcontig.c
index fce1ba9..a63a9ce 100644
--- a/src/H5Fcontig.c
+++ b/src/H5Fcontig.c
@@ -36,8 +36,11 @@ static int		interface_initialize_g = 0;
 /* Declare a PQ free list to manage the sieve buffer information */
 H5FL_BLK_DEFINE(sieve_buf);
 
-/* Extern the free list to manage blocks of type conversion data */
-H5FL_BLK_EXTERN(type_conv);
+/* Declare the free list to manage blocks of non-zero fill-value data */
+H5FL_BLK_DEFINE_STATIC(non_zero_fill);
+
+/* Declare the free list to manage blocks of zero fill-value data */
+H5FL_BLK_DEFINE_STATIC(zero_fill);
 
 
 /*-------------------------------------------------------------------------
@@ -56,11 +59,10 @@ H5FL_BLK_EXTERN(type_conv);
  */
 herr_t
 H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
-    struct H5P_genplist_t *dc_plist, const struct H5S_t *space,
-    size_t elmt_size)
+    struct H5P_genplist_t *dc_plist, const struct H5O_efl_t *efl,
+    const struct H5S_t *space,
+    const struct H5O_fill_t *fill, size_t elmt_size)
 {
-    H5O_fill_t  fill;           /* Fill value information */
-    H5O_efl_t   efl;            /* External File List info */
     hssize_t    snpoints;       /* Number of points in space (for error checking) */
     size_t      npoints;        /* Number of points in space */
     size_t      ptsperbuf;      /* Maximum # of points which fit in the buffer */
@@ -77,6 +79,7 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
     unsigned    blocks_written=0; /* Flag to indicate that chunk was actually written */
     unsigned    using_mpi=0;    /* Flag to indicate that the file is being accessed with an MPI-capable file driver */
 #endif /* H5_HAVE_PARALLEL */
+    int         non_zero_fill_f=(-1);   /* Indicate that a non-zero fill-value was used */
     herr_t	ret_value=SUCCEED;	/* Return value */
     
     FUNC_ENTER_NOAPI(H5F_contig_fill, FAIL);
@@ -91,12 +94,6 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
     assert(space);
     assert(elmt_size>0);
 
-    /* Get necessary properties from dataset creation property list */
-    if(H5P_get(dc_plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
-        HGOTO_ERROR(H5E_STORAGE, H5E_CANTGET, FAIL, "can't get fill value");
-    if(H5P_get(dc_plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't retrieve external file list");
-
 #ifdef H5_HAVE_PARALLEL
     /* Retrieve up MPI parameters */
     if(IS_H5FD_MPIO(f)) {
@@ -136,46 +133,62 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
     assert(snpoints>=0);
     H5_ASSIGN_OVERFLOW(npoints,snpoints,hssize_t,size_t);
 
-    /* Don't write default fill-values to external files */
-    if(efl.nused>0 && !fill.buf)
-        HGOTO_DONE(SUCCEED);
-
-    /* If fill value is library default, use the element size */
-    if(!fill.buf)
-        fill.size=elmt_size;
+    /* If fill value is not library default, use it to set the element size */
+    if(fill->buf)
+        elmt_size=fill->size;
 
     /*
      * Fill the entire current extent with the fill value.  We can do
      * this quite efficiently by making sure we copy the fill value
      * in relatively large pieces.
      */
-     ptsperbuf = MAX(1, bufsize/fill.size);
-     bufsize = ptsperbuf*fill.size;
-
-     /* Allocate temporary buffer */
-     if ((buf=H5FL_BLK_ALLOC(type_conv,bufsize,0))==NULL)
-         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for fill buffer");
-
-     /* Fill the buffer with the user's fill value */
-     if(fill.buf)
-        H5V_array_fill(buf, fill.buf, fill.size, ptsperbuf);
-     else /* Fill the buffer with the default fill value */
-        HDmemset(buf,0,bufsize);
+     ptsperbuf = MAX(1, bufsize/elmt_size);
+     bufsize = ptsperbuf*elmt_size;
+
+    /* Fill the buffer with the user's fill value */
+    if(fill->buf) {
+        /* Allocate temporary buffer */
+        if ((buf=H5FL_BLK_MALLOC(non_zero_fill,bufsize))==NULL)
+            HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for fill buffer");
+
+        H5V_array_fill(buf, fill->buf, elmt_size, ptsperbuf);
+
+        /* Indicate that a non-zero fill buffer was used */
+        non_zero_fill_f=1;
+    } /* end if */
+    else {      /* Fill the buffer with the default fill value */
+        htri_t buf_avail;
+
+        /* Check if there is an already zeroed out buffer available */
+        buf_avail=H5FL_BLK_AVAIL(zero_fill,bufsize);
+        assert(buf_avail!=FAIL);
+
+        /* Allocate temporary buffer (zeroing it if no buffer is available) */
+        if(!buf_avail)
+            buf=H5FL_BLK_CALLOC(zero_fill,bufsize);
+        else
+            buf=H5FL_BLK_MALLOC(zero_fill,bufsize);
+        if(buf==NULL)
+            HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for fill buffer");
+
+        /* Indicate that a zero fill buffer was used */
+        non_zero_fill_f=0;
+    } /* end else */
      
-     /* Start at the beginning of the dataset */
-     addr = 0;
+    /* Start at the beginning of the dataset */
+    addr = 0;
 
-     /* Loop through writing the fill value to the dataset */
-     while (npoints>0) {
-          size = MIN(ptsperbuf, npoints) * fill.size;
+    /* Loop through writing the fill value to the dataset */
+    while (npoints>0) {
+          size = MIN(ptsperbuf, npoints) * elmt_size;
 
 #ifdef H5_HAVE_PARALLEL
             /* Check if this file is accessed with an MPI-capable file driver */
             if(using_mpi) {
                 /* Round-robin write the chunks out from only one process */
                 if(mpi_round==mpi_rank) {
-                    if (H5F_seq_write(f, dxpl_id, layout, dc_plist, space,
-                            fill.size, size, addr, buf)<0)
+                    if (H5F_seq_write(f, dxpl_id, layout, dc_plist, efl, space,
+                            elmt_size, size, addr, buf)<0)
                         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to write fill value to dataset");
                 } /* end if */
                 mpi_round=(++mpi_round)%mpi_size;
@@ -185,8 +198,8 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
             } /* end if */
             else {
 #endif /* H5_HAVE_PARALLEL */
-                if (H5F_seq_write(f, dxpl_id, layout, dc_plist, space,
-                        fill.size, size, addr, buf)<0)
+                if (H5F_seq_write(f, dxpl_id, layout, dc_plist, efl, space,
+                        elmt_size, size, addr, buf)<0)
                     HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to write fill value to dataset");
 #ifdef H5_HAVE_PARALLEL
             } /* end else */
@@ -211,8 +224,13 @@ H5F_contig_fill(H5F_t *f, hid_t dxpl_id, struct H5O_layout_t *layout,
 
 done:
     /* Free the buffer for fill values */
-    if (buf)
-        H5FL_BLK_FREE(type_conv,buf);
+    if (buf) {
+        assert(non_zero_fill_f>=0);
+        if(non_zero_fill_f)
+            H5FL_BLK_FREE(non_zero_fill,buf);
+        else
+            H5FL_BLK_FREE(zero_fill,buf);
+    } /* end if */
 
     FUNC_LEAVE(ret_value);
 }
@@ -661,7 +679,7 @@ H5F_contig_readv(H5F_t *f, hsize_t _max_data, H5FD_mem_t type, haddr_t _addr,
                 } /* end if */
                 else {
                     /* Allocate room for the data sieve buffer */
-                    if (NULL==(f->shared->sieve_buf=H5FL_BLK_ALLOC(sieve_buf,f->shared->sieve_buf_size,0)))
+                    if (NULL==(f->shared->sieve_buf=H5FL_BLK_MALLOC(sieve_buf,f->shared->sieve_buf_size)))
                         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
                     /* Determine the new sieve buffer size & location */
@@ -1128,7 +1146,7 @@ H5F_contig_writev(H5F_t *f, hsize_t _max_data, H5FD_mem_t type, haddr_t _addr,
                 } /* end if */
                 else {
                     /* Allocate room for the data sieve buffer */
-                    if (NULL==(f->shared->sieve_buf=H5FL_BLK_ALLOC(sieve_buf,f->shared->sieve_buf_size,0)))
+                    if (NULL==(f->shared->sieve_buf=H5FL_BLK_MALLOC(sieve_buf,f->shared->sieve_buf_size)))
                         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
                     /* Determine the new sieve buffer size & location */
diff --git a/src/H5Fistore.c b/src/H5Fistore.c
index ea74165..f617092 100644
--- a/src/H5Fistore.c
+++ b/src/H5Fistore.c
@@ -862,7 +862,7 @@ H5F_istore_init (H5F_t *f)
     HDmemset (rdcc, 0, sizeof(H5F_rdcc_t));
     if (f->shared->rdcc_nbytes>0 && f->shared->rdcc_nelmts>0) {
 	rdcc->nslots = f->shared->rdcc_nelmts;
-	rdcc->slot = H5FL_ARR_ALLOC (H5F_rdcc_ent_ptr_t,rdcc->nslots,1);
+	rdcc->slot = H5FL_ARR_CALLOC (H5F_rdcc_ent_ptr_t,rdcc->nslots);
 	if (NULL==rdcc->slot)
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     }
@@ -1440,7 +1440,7 @@ H5F_istore_lock(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
             HGOTO_ERROR(H5E_IO, H5E_CANTINIT, NULL, "unable to preempt chunk(s) from cache");
 
         /* Create a new entry */
-        ent = H5FL_ALLOC(H5F_rdcc_ent_t,0);
+        ent = H5FL_MALLOC(H5F_rdcc_ent_t);
         ent->locked = 0;
         ent->dirty = FALSE;
         ent->chunk_size = chunk_size;
@@ -1943,8 +1943,9 @@ H5F_istore_write(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
 
 #ifdef H5_HAVE_PARALLEL
             /* Additional sanity check when operating in parallel */
-            if (chunk_addr==HADDR_UNDEF || pline.nfilters>0)
+            if (chunk_addr==HADDR_UNDEF || pline.nfilters>0) {
                 HGOTO_ERROR (H5E_IO, H5E_WRITEERROR, FAIL, "unable to locate raw data chunk");
+            }
 #endif /* H5_HAVE_PARALLEL */
             
             /*
@@ -2312,7 +2313,7 @@ done:
  */
 herr_t
 H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
-		    const hsize_t *space_dim, H5P_genplist_t *dc_plist)
+        const hsize_t *space_dim, H5P_genplist_t *dc_plist, hbool_t full_overwrite)
 {
     hssize_t	chunk_offset[H5O_LAYOUT_NDIMS]; /* Offset of current chunk */
     hsize_t	chunk_size;     /* Size of chunk in bytes */
@@ -2407,7 +2408,7 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     } /* end for */
 
     /* Check if fill values should be written to blocks */
-    if(fill_time != H5D_FILL_TIME_NEVER) {
+    if(fill_time != H5D_FILL_TIME_NEVER && !full_overwrite) {
         /* Allocate chunk buffer for processes to use when writing fill values */
         H5_CHECK_OVERFLOW(chunk_size,hsize_t,size_t);
         if (NULL==(chunk = H5MM_malloc((size_t)chunk_size)))
@@ -2484,7 +2485,7 @@ H5F_istore_allocate(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
                 HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "unable to allocate chunk");
 
             /* Check if fill values should be written to blocks */
-            if(fill_time != H5D_FILL_TIME_NEVER) {
+            if(fill_time != H5D_FILL_TIME_NEVER && !full_overwrite) {
 #ifdef H5_HAVE_PARALLEL
                 /* Check if this file is accessed with an MPI-capable file driver */
                 if(using_mpi) {
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 4c42ced..9326060 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -17,10 +17,13 @@
 #define _H5Fpkg_H
 
 #include "H5Fprivate.h"
+#include "H5FOprivate.h"        /* File objects                         */
 
 /* This is a near top-level header! Try not to include much! */
 #include "H5private.h"
 
+#include "H5Bpublic.h"          /* B-tree header, for H5B_NUM_BTREE_ID */
+
 /*
  * Feature: Define this constant to be non-zero if you want to enable code
  *	    that minimizes the number of calls to lseek().  This has a huge
@@ -94,6 +97,13 @@ typedef struct H5F_file_t {
     H5FD_t	*lf; 		/* Lower level file handle for I/O	*/
     unsigned	nrefs;		/* Ref count for times file is opened	*/
     uint32_t	consist_flags;	/* File Consistency Flags		*/
+
+    /* Cached values from FCPL */
+    size_t	sizeof_addr;	/* Size of addresses in file            */
+    size_t	sizeof_size;	/* Size of offsets in file              */
+    unsigned	sym_leaf_k;	/* Size of leaves in symbol tables      */
+    int btree_k[H5B_NUM_BTREE_ID];  /* B-tree key values for each type  */
+
     haddr_t	boot_addr;	/* Absolute address of boot block	*/
     haddr_t	base_addr;	/* Absolute base address for rel.addrs. */
     haddr_t	freespace_addr;	/* Relative address of free-space info	*/
@@ -110,8 +120,9 @@ typedef struct H5F_file_t {
     hsize_t	alignment;	/* Alignment				*/
     unsigned	gc_ref;		/* Garbage-collect references?		*/
     struct H5G_t *root_grp;	/* Open root group			*/
-    int	ncwfs;		/* Num entries on cwfs list		*/
+    int	ncwfs;			/* Num entries on cwfs list		*/
     struct H5HG_heap_t **cwfs;	/* Global heap cache			*/
+    H5FO_t *open_objs;          /* Open objects in file                 */
 
     /* Data Sieve Buffering fields */
     unsigned char *sieve_buf;   /* Buffer to hold data sieve buffer */
@@ -121,7 +132,7 @@ typedef struct H5F_file_t {
     unsigned sieve_dirty;       /* Flag to indicate that the data sieve buffer is dirty */
 
     H5F_rdcc_t	rdcc;		/* Raw data chunk cache			*/
-    H5F_close_degree_t fc_degree;	/* File close behavior degree	*/
+    H5F_close_degree_t fc_degree;   /* File close behavior degree	*/
 } H5F_file_t;
 
 /* A record of the mount table */
diff --git a/src/H5Fprivate.h b/src/H5Fprivate.h
index 42f174c..395b5e2 100644
--- a/src/H5Fprivate.h
+++ b/src/H5Fprivate.h
@@ -152,8 +152,10 @@ typedef struct H5F_t H5F_t;
 				 (X)+(haddr_t)(Z)<(X))
 #define H5F_addr_hash(X,M)	((unsigned)((X)%(M)))
 #define H5F_addr_defined(X)	(X!=HADDR_UNDEF)
+/* The H5F_addr_eq() macro guarantees that Y is not HADDR_UNDEF by making
+ * certain that X is not HADDR_UNDEF and then checking that X equals Y
+ */
 #define H5F_addr_eq(X,Y)	((X)!=HADDR_UNDEF &&			      \
-				 (Y)!=HADDR_UNDEF &&			      \
 				 (X)==(Y))
 #define H5F_addr_ne(X,Y)	(!H5F_addr_eq((X),(Y)))
 #define H5F_addr_lt(X,Y) 	((X)!=HADDR_UNDEF &&			      \
@@ -174,12 +176,22 @@ typedef struct H5F_t H5F_t;
 #define H5F_addr_overlap(O1,L1,O2,L2) ((O1<O2 && (O1+L1)>O2) ||               \
                                  (O1>=O2 && O1<(O2+L2)))
 
+/* If the module using this macro is allowed access to the private variables, access them directly */
+#ifdef H5F_PACKAGE
 /* size of size_t and off_t as they exist on disk */
+#define H5F_SIZEOF_ADDR(F)      ((F)->shared->sizeof_addr)
+#define H5F_SIZEOF_SIZE(F)      ((F)->shared->sizeof_size)
+/* Size of symbol table leafs */
+#define H5F_SYM_LEAF_K(F)       ((F)->shared->sym_leaf_k)
+/* B-tree key value size */
+#define H5F_KVALUE(F,T)         ((F)->shared->btree_k[(T)->id])
+#else /* H5F_PACKAGE */
 #define H5F_SIZEOF_ADDR(F)      (H5F_sizeof_addr(F))
 #define H5F_SIZEOF_SIZE(F)      (H5F_sizeof_size(F))
+#define H5F_SYM_LEAF_K(F)       (H5F_sym_leaf_k(F))
+#define H5F_KVALUE(F,T)         (H5F_Kvalue(F,T))
+#endif /* H5F_PACKAGE */
 
-H5_DLL size_t H5F_sizeof_addr(const H5F_t *f);
-H5_DLL size_t H5F_sizeof_size(const H5F_t *f);
 
 /* Macros to encode/decode offset/length's for storing in the file */
 #ifdef NOT_YET
@@ -344,6 +356,7 @@ struct H5O_pline_t;
 struct H5O_fill_t;
 struct H5P_genplist_t;
 struct H5S_t;
+struct H5B_class_t;
 
 /* Private functions, not part of the publicly documented API */
 H5_DLL herr_t H5F_init(void);
@@ -356,6 +369,17 @@ H5_DLL herr_t H5F_get_obj_ids(H5F_t *f, unsigned types, hid_t *obj_id_list);
 H5_DLL herr_t H5F_get_vfd_handle(H5F_t *file, hid_t fapl, void** file_handle);
 H5_DLL haddr_t H5F_get_base_addr(const H5F_t *f);
 
+/* Functions than check file mounting information */
+H5_DLL htri_t H5F_is_mount(const H5F_t *file);
+H5_DLL htri_t H5F_has_mount(const H5F_t *file);
+
+/* Functions than retrieve values set from the FCPL */
+H5_DLL size_t H5F_sizeof_addr(const H5F_t *f);
+H5_DLL size_t H5F_sizeof_size(const H5F_t *f);
+H5_DLL unsigned H5F_sym_leaf_k(const H5F_t *f);
+H5_DLL int H5F_Kvalue(const H5F_t *f, const struct H5B_class_t *type);
+
+
 /* Functions that operate on array storage */
 H5_DLL herr_t H5F_arr_read (H5F_t *f, hid_t dxpl_id,
                             const struct H5O_layout_t *layout,
@@ -381,24 +405,24 @@ H5_DLL herr_t H5F_block_write(H5F_t *f, H5FD_mem_t type, haddr_t addr,
 /* Functions that operate on byte sequences */
 H5_DLL herr_t H5F_seq_read(H5F_t *f, hid_t dxpl_id,
         const struct H5O_layout_t *layout,
-        struct H5P_genplist_t *dc_plist,
+        struct H5P_genplist_t *dc_plist, const struct H5O_efl_t *efl,
         const struct H5S_t *file_space, size_t elmt_size, size_t seq_len,
         hsize_t file_offset, void *_buf/*out*/);
 H5_DLL herr_t H5F_seq_write (H5F_t *f, hid_t dxpl_id,
         struct H5O_layout_t *layout,
-        struct H5P_genplist_t *dc_plist,
+        struct H5P_genplist_t *dc_plist, const struct H5O_efl_t *efl,
         const struct H5S_t *file_space, size_t elmt_size, size_t seq_len,
         hsize_t file_offset, const void *_buf);
 
 /* Functions that operate on vectors of byte sequences */
 H5_DLL herr_t H5F_seq_readv(H5F_t *f, hid_t dxpl_id,
         const struct H5O_layout_t *layout,
-        struct H5P_genplist_t *dc_plist,
+        struct H5P_genplist_t *dc_plist, const struct H5O_efl_t *efl,
         const struct H5S_t *file_space, size_t elmt_size, size_t nseq,
         size_t seq_len[], hsize_t file_offset[], void *_buf/*out*/);
 H5_DLL herr_t H5F_seq_writev(H5F_t *f, hid_t dxpl_id,
         struct H5O_layout_t *layout,
-        struct H5P_genplist_t *dc_plist,
+        struct H5P_genplist_t *dc_plist, const struct H5O_efl_t *efl,
         const struct H5S_t *file_space, size_t elmt_size, size_t nseq,
         size_t seq_len[], hsize_t file_offset[], const void *_buf);
 
@@ -406,15 +430,15 @@ H5_DLL herr_t H5F_seq_writev(H5F_t *f, hid_t dxpl_id,
 /* Functions that operate on contiguous storage */
 H5_DLL herr_t H5F_contig_fill(H5F_t *f, hid_t dxpl_id,
         struct H5O_layout_t *layout, struct H5P_genplist_t *dc_plist,
-        const struct H5S_t *space, size_t elmt_size);
+        const struct H5O_efl_t *efl, const struct H5S_t *space,
+        const struct H5O_fill_t *fill, size_t elmt_size);
 
 /* Functions that operate on indexed storage */
 H5_DLL herr_t H5F_istore_create(H5F_t *f,
 				 struct H5O_layout_t *layout/*in,out*/);
 H5_DLL herr_t H5F_istore_allocate (H5F_t *f, hid_t dxpl_id,
-                                const struct H5O_layout_t *layout,
-                                const hsize_t *space_dim,
-                                struct H5P_genplist_t *dc_plist);
+    const struct H5O_layout_t *layout, const hsize_t *space_dim,
+    struct H5P_genplist_t *dc_plist, hbool_t full_overwrite);
 H5_DLL hsize_t H5F_istore_allocated(H5F_t *f, unsigned ndims, haddr_t addr);
 H5_DLL herr_t H5F_istore_dump_btree(H5F_t *f, FILE *stream, unsigned ndims,
         haddr_t addr);
diff --git a/src/H5Fpublic.h b/src/H5Fpublic.h
index adddd83..edee20b 100644
--- a/src/H5Fpublic.h
+++ b/src/H5Fpublic.h
@@ -28,13 +28,25 @@
  * which are compatible with the library to which the application is linked.
  * We're assuming that these constants are used rather early in the hdf5
  * session.
+ *
+ * NOTE: When adding H5F_ACC_* macros, remember to redefine them in H5Fprivate.h
+ *
  */
-#define H5F_ACC_RDONLY	(H5check(),0x0000u)	/*absence of rdwr => rd-only */
-#define H5F_ACC_RDWR	(H5check(),0x0001u)	/*open for read and write    */
-#define H5F_ACC_TRUNC	(H5check(),0x0002u)	/*overwrite existing files   */
-#define H5F_ACC_EXCL	(H5check(),0x0004u)	/*fail if file already exists*/
-#define H5F_ACC_DEBUG	(H5check(),0x0008u)	/*print debug info	     */
-#define H5F_ACC_CREAT	(H5check(),0x0010u)	/*create non-existing files  */
+
+/* When this header is included from H5Fprivate.h, don't make calls to H5check() */
+#undef H5CHECK
+#ifndef _H5Fprivate_H
+#define H5CHECK          H5check(),
+#else   /* _H5Fprivate_H */
+#define H5CHECK
+#endif  /* _H5Fprivate_H */
+
+#define H5F_ACC_RDONLY	(H5CHECK 0x0000u)	/*absence of rdwr => rd-only */
+#define H5F_ACC_RDWR	(H5CHECK 0x0001u)	/*open for read and write    */
+#define H5F_ACC_TRUNC	(H5CHECK 0x0002u)	/*overwrite existing files   */
+#define H5F_ACC_EXCL	(H5CHECK 0x0004u)	/*fail if file already exists*/
+#define H5F_ACC_DEBUG	(H5CHECK 0x0008u)	/*print debug info	     */
+#define H5F_ACC_CREAT	(H5CHECK 0x0010u)	/*create non-existing files  */
 
 #define H5F_OBJ_FILE	(0x0001u)
 #define H5F_OBJ_DATASET	(0x0002u)
diff --git a/src/H5Fseq.c b/src/H5Fseq.c
index 6176003..9592725 100644
--- a/src/H5Fseq.c
+++ b/src/H5Fseq.c
@@ -59,9 +59,9 @@ static int interface_initialize_g = 0;
  */
 herr_t
 H5F_seq_read(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist,
-        const H5S_t *file_space, size_t elmt_size,
-        size_t seq_len, hsize_t dset_offset, void *buf/*out*/)
+    H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
+    const H5S_t *file_space, size_t elmt_size,
+    size_t seq_len, hsize_t dset_offset, void *buf/*out*/)
 {
     herr_t      ret_value=SUCCEED;       /* Return value */
 
@@ -70,10 +70,11 @@ H5F_seq_read(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     /* Check args */
     assert(f);
     assert(layout);
+    assert(efl);
     assert(buf);
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
 
-    if (H5F_seq_readv(f, dxpl_id, layout, dc_plist, file_space, elmt_size, 1, &seq_len, &dset_offset, buf)<0)
+    if (H5F_seq_readv(f, dxpl_id, layout, dc_plist, efl, file_space, elmt_size, 1, &seq_len, &dset_offset, buf)<0)
         HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "vector read failed");
 
 done:
@@ -104,9 +105,9 @@ done:
  */
 herr_t
 H5F_seq_write(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist,
-        const H5S_t *file_space, size_t elmt_size,
-        size_t seq_len, hsize_t dset_offset, const void *buf)
+    H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
+    const H5S_t *file_space, size_t elmt_size,
+    size_t seq_len, hsize_t dset_offset, const void *buf)
 {
     herr_t      ret_value=SUCCEED;       /* Return value */
 
@@ -115,10 +116,11 @@ H5F_seq_write(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
     /* Check args */
     assert(f);
     assert(layout);
+    assert(efl);
     assert(buf);
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
 
-    if (H5F_seq_writev(f, dxpl_id, layout, dc_plist, file_space, elmt_size, 1, &seq_len, &dset_offset, buf)<0)
+    if (H5F_seq_writev(f, dxpl_id, layout, dc_plist, efl, file_space, elmt_size, 1, &seq_len, &dset_offset, buf)<0)
         HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "vector write failed");
 
 done:
@@ -151,7 +153,7 @@ done:
  */
 herr_t
 H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist,
+        H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
         const H5S_t *file_space, size_t elmt_size,
         size_t nseq, size_t seq_len_arr[], hsize_t dset_offset_arr[],
         void *_buf/*out*/)
@@ -172,7 +174,6 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     unsigned	u;				/*counters		*/
     size_t      v;                              /*counters              */
     int	i,j;				/*counters		*/
-    struct H5O_efl_t efl;               /* External File List info */
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;
     H5P_genplist_t *plist=NULL;                 /* Property list */
@@ -184,6 +185,7 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
     /* Check args */
     assert(f);
     assert(layout);
+    assert(efl);
     assert(real_buf);
     /* Make certain we have the correct type of property list */
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
@@ -221,14 +223,10 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
         HGOTO_ERROR (H5E_DATASET, H5E_READERROR, FAIL, "collective access on non-contiguous datasets not supported yet");
 #endif /* H5_HAVE_PARALLEL */
 
-    /* Get necessary properties from property list */
-    if(H5P_get(dc_plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get EFL value");
-
     switch (layout->type) {
         case H5D_CONTIGUOUS:
             /* Read directly from file if the dataset is in an external file */
-            if (efl.nused>0) {
+            if (efl->nused>0) {
                 /* Iterate through the sequence vectors */
                 for(v=0; v<nseq; v++) {
 #ifdef H5_HAVE_PARALLEL
@@ -260,7 +258,7 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
                      *  file offsets, totally mixing up the data sieve buffer information. -QAK
                      */
                     H5_CHECK_OVERFLOW(dset_offset_arr[v],hsize_t,haddr_t);
-                    if (H5O_efl_read(f, &efl, (haddr_t)dset_offset_arr[v], seq_len_arr[v], real_buf)<0)
+                    if (H5O_efl_read(f, efl, (haddr_t)dset_offset_arr[v], seq_len_arr[v], real_buf)<0)
                         HGOTO_ERROR(H5E_IO, H5E_READERROR, FAIL, "external data read failed");
 
                     /* Increment offset in buffer */
@@ -281,7 +279,7 @@ H5F_seq_readv(H5F_t *f, hid_t dxpl_id, const H5O_layout_t *layout,
             /*
              * This method is unable to access external raw data files 
              */
-            if (efl.nused>0)
+            if (efl->nused>0)
                 HGOTO_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "chunking and external files are mutually exclusive");
 
             /* Compute the file offset coordinates and hyperslab size */
@@ -542,7 +540,7 @@ done:
  */
 herr_t
 H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist,
+        H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
         const H5S_t *file_space, size_t elmt_size,
         size_t nseq, size_t seq_len_arr[], hsize_t dset_offset_arr[],
         const void *_buf)
@@ -563,7 +561,6 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
     unsigned	u;				/*counters		*/
     size_t      v;                              /*counters              */
     int	i,j;				/*counters		*/
-    struct H5O_efl_t efl;               /* External File List info */
 #ifdef H5_HAVE_PARALLEL
     H5FD_mpio_xfer_t xfer_mode=H5FD_MPIO_INDEPENDENT;
     H5P_genplist_t *plist=NULL;                 /* Property list */
@@ -575,6 +572,7 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
     /* Check args */
     assert(f);
     assert(layout);
+    assert(efl);
     assert(real_buf);
     /* Make certain we have the correct type of property list */
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
@@ -612,14 +610,10 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
         HGOTO_ERROR (H5E_DATASET, H5E_WRITEERROR, FAIL, "collective access on chunked datasets not supported yet");
 #endif /* H5_HAVE_PARALLEL */
 
-    /* Get necessary properties from property list */
-    if(H5P_get(dc_plist, H5D_CRT_EXT_FILE_LIST_NAME, &efl) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get EFL value");
-
     switch (layout->type) {
         case H5D_CONTIGUOUS:
             /* Write directly to file if the dataset is in an external file */
-            if (efl.nused>0) {
+            if (efl->nused>0) {
                 /* Iterate through the sequence vectors */
                 for(v=0; v<nseq; v++) {
 #ifdef H5_HAVE_PARALLEL
@@ -650,7 +644,7 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
                      *  file offsets, totally mixing up the data sieve buffer information. -QAK
                      */
                     H5_CHECK_OVERFLOW(dset_offset_arr[v],hsize_t,haddr_t);
-                    if (H5O_efl_write(f, &efl, (haddr_t)dset_offset_arr[v], seq_len_arr[v], real_buf)<0)
+                    if (H5O_efl_write(f, efl, (haddr_t)dset_offset_arr[v], seq_len_arr[v], real_buf)<0)
                         HGOTO_ERROR(H5E_IO, H5E_WRITEERROR, FAIL, "external data write failed");
 
                     /* Increment offset in buffer */
@@ -671,7 +665,7 @@ H5F_seq_writev(H5F_t *f, hid_t dxpl_id, H5O_layout_t *layout,
             /*
              * This method is unable to access external raw data files 
              */
-            if (efl.nused>0)
+            if (efl->nused>0)
                 HGOTO_ERROR(H5E_IO, H5E_UNSUPPORTED, FAIL, "chunking and external files are mutually exclusive");
 
             /* Compute the file offset coordinates and hyperslab size */
diff --git a/src/H5G.c b/src/H5G.c
index d6d4ea1..bc63e05 100644
--- a/src/H5G.c
+++ b/src/H5G.c
@@ -111,16 +111,25 @@ static size_t H5G_comp_alloc_g = 0;             /*sizeof component buffer */
 /* Struct only used by change name callback function */
 typedef struct H5G_names_t {
     H5G_entry_t	*loc;
-    const char *src_name;
+    H5RS_str_t *src_name;
     H5G_entry_t	*src_loc;
-    const char *dst_name;
+    H5RS_str_t *dst_name;
     H5G_entry_t	*dst_loc;
     H5G_names_op_t op;
 } H5G_names_t;  
 
+/* Enum for H5G_namei actions */
+typedef enum {
+    H5G_NAMEI_TRAVERSE,         /* Just traverse groups */
+    H5G_NAMEI_INSERT            /* Insert entry in group */
+}H5G_namei_act_t ;
+
 /* Declare a free list to manage the H5G_t struct */
 H5FL_DEFINE(H5G_t);
 
+/* Declare extern the PQ free list for the wrapped strings */
+H5FL_BLK_EXTERN(str_buf);
+
 /* Private prototypes */
 static herr_t H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key);
 static herr_t H5G_traverse_slink(H5G_entry_t *grp_ent/*in,out*/,
@@ -1186,21 +1195,28 @@ H5G_basename(const char *name, size_t *size_p)
  *      Modified to deep copies of symbol table entries
  *      Added `id to name' support.
  *
+ *      Quincey Koziol, 2003-01-06
+ *      Added "action" and "ent" parameters to allow different actions when
+ *      working on the last component of a name.  (Specifically, this allows
+ *      inserting an entry into a group, instead of trying to look it up)
+ *
  *-------------------------------------------------------------------------
  */
 static herr_t
 H5G_namei(H5G_entry_t *loc_ent, const char *name, const char **rest/*out*/,
 	  H5G_entry_t *grp_ent/*out*/, H5G_entry_t *obj_ent/*out*/,
-	  unsigned target, int *nlinks/*out*/)
+	  unsigned target, int *nlinks/*out*/, H5G_namei_act_t action,
+          H5G_entry_t *ent)
 {
     H5G_entry_t		  _grp_ent;     /*entry for current group	*/
     H5G_entry_t		  _obj_ent;     /*entry found			*/
     size_t		  nchars;	/*component name length		*/
     int			  _nlinks = H5G_NLINKS;
     const char		   *s = NULL;
-    unsigned null_obj = obj_ent == NULL ? 1 : 0;        /* Flag to indicate this function was called with obj_ent set to NULL */
-    unsigned null_grp = grp_ent == NULL ? 1 : 0;        /* Flag to indicate this function was called with grp_ent set to NULL */
-    unsigned group_copy = 0;            /* Flag to indicate that the group entry is copied */
+    unsigned null_obj;          /* Flag to indicate this function was called with obj_ent set to NULL */
+    unsigned null_grp;          /* Flag to indicate this function was called with grp_ent set to NULL */
+    unsigned group_copy = 0;    /* Flag to indicate that the group entry is copied */
+    unsigned last_comp = 0;     /* Flag to indicate that a component is the last component in the name */
     herr_t      ret_value=SUCCEED;       /* Return value */
     
     FUNC_ENTER_NOINIT(H5G_namei);
@@ -1209,13 +1225,17 @@ H5G_namei(H5G_entry_t *loc_ent, const char *name, const char **rest/*out*/,
     if (rest)
         *rest = name;
     if (!grp_ent) {
-        HDmemset(&_grp_ent,0,sizeof(H5G_entry_t));
         grp_ent = &_grp_ent;
+        null_grp = 1;
     } /* end if */
+    else
+        null_grp = 0;
     if (!obj_ent) {
-        HDmemset(&_obj_ent,0,sizeof(H5G_entry_t));
         obj_ent = &_obj_ent;
+        null_obj = 1;
     } /* end if */
+    else
+        null_obj = 0;
     if (!nlinks)
         nlinks = &_nlinks;
     
@@ -1293,21 +1313,46 @@ H5G_namei(H5G_entry_t *loc_ent, const char *name, const char **rest/*out*/,
 	/* Set flag that we've copied a new entry into the group entry */
 	group_copy =1;
 
-	if (H5G_stab_find(grp_ent, H5G_comp_g, obj_ent/*out*/ )<0) {
-	    /*
-	     * Component was not found in the current symbol table, possibly
-	     * because GRP_ENT isn't a symbol table.
-	     */
-	    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "component not found");
-	}
+        /* Check if this is the last component of the name */
+        if(!((s=H5G_component(name+nchars, NULL)) && *s))
+            last_comp=1;
+
+        switch(action) {
+            case H5G_NAMEI_TRAVERSE:
+                if (H5G_stab_find(grp_ent, H5G_comp_g, obj_ent/*out*/ )<0) {
+                    /*
+                     * Component was not found in the current symbol table, possibly
+                     * because GRP_ENT isn't a symbol table.
+                     */
+                    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "component not found");
+                }
+                break;
+
+            case H5G_NAMEI_INSERT:
+                if(!last_comp) {
+                    if (H5G_stab_find(grp_ent, H5G_comp_g, obj_ent/*out*/ )<0) {
+                        /*
+                         * Component was not found in the current symbol table, possibly
+                         * because GRP_ENT isn't a symbol table.
+                         */
+                        HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "component not found");
+                    }
+                } /* end if */
+                else {
+                    if (H5G_stab_insert(grp_ent, H5G_comp_g, ent) < 0)
+                        HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, FAIL, "unable to insert name");
+                    HGOTO_DONE(SUCCEED);
+                } /* end else */
+                break;
+        } /* end switch */
 
 	/*
 	 * If we found a symbolic link then we should follow it.  But if this
 	 * is the last component of the name and the H5G_TARGET_SLINK bit of
 	 * TARGET is set then we don't follow it.
 	 */
-	if(H5G_CACHED_SLINK==obj_ent->type && (0==(target & H5G_TARGET_SLINK) ||
-                ((s=H5G_component(name+nchars, NULL)) && *s))) {
+	if(H5G_CACHED_SLINK==obj_ent->type &&
+                (0==(target & H5G_TARGET_SLINK) || !last_comp)) {
 	    if ((*nlinks)-- <= 0)
 		HGOTO_ERROR (H5E_SYM, H5E_SLINK, FAIL, "too many symbolic links");
 	    if (H5G_traverse_slink (grp_ent, obj_ent, nlinks)<0)
@@ -1319,10 +1364,8 @@ H5G_namei(H5G_entry_t *loc_ent, const char *name, const char **rest/*out*/,
 	 * the H5G_TARGET_MOUNT bit of TARGET is set and this is the last
 	 * component of the name.
 	 */
-	if (0==(target & H5G_TARGET_MOUNT) ||
-                ((s=H5G_component(name+nchars, NULL)) && *s)) {
+	if (0==(target & H5G_TARGET_MOUNT) || !last_comp)
 	    H5F_mountpoint(obj_ent/*in,out*/);
-	}
 	
 	/* next component */
 	name += nchars;
@@ -1376,7 +1419,7 @@ H5G_traverse_slink (H5G_entry_t *grp_ent/*in,out*/,
     const char		*clv = NULL;		/*cached link value	*/
     char		*linkval = NULL;	/*the copied link value	*/
     H5G_entry_t         tmp_grp_ent;            /* Temporary copy of group entry */
-    char                *tmp_user_path=NULL, *tmp_canon_path=NULL; /* Temporary pointer to object's user path & canonical path */
+    H5RS_str_t          *tmp_user_path_r=NULL, *tmp_canon_path_r=NULL; /* Temporary pointer to object's user path & canonical path */
     herr_t      ret_value=SUCCEED;       /* Return value */
     
     FUNC_ENTER_NOAPI(H5G_traverse_slink, FAIL);
@@ -1393,10 +1436,10 @@ H5G_traverse_slink (H5G_entry_t *grp_ent/*in,out*/,
     linkval = H5MM_xstrdup (clv);
 		
     /* Hold the entry's name (& old_name) to restore later */
-    tmp_user_path=obj_ent->user_path;
-    obj_ent->user_path=NULL;
-    tmp_canon_path=obj_ent->canon_path;
-    obj_ent->canon_path=NULL;
+    tmp_user_path_r=obj_ent->user_path_r;
+    obj_ent->user_path_r=NULL;
+    tmp_canon_path_r=obj_ent->canon_path_r;
+    obj_ent->canon_path_r=NULL;
 
     /* Free the names for the group entry */
     H5G_free_ent_name(grp_ent);
@@ -1405,24 +1448,24 @@ H5G_traverse_slink (H5G_entry_t *grp_ent/*in,out*/,
     H5G_ent_copy(&tmp_grp_ent,grp_ent,H5G_COPY_DEEP);
 
     /* Traverse the link */
-    if (H5G_namei (&tmp_grp_ent, linkval, NULL, grp_ent, obj_ent, H5G_TARGET_NORMAL, nlinks))
+    if (H5G_namei (&tmp_grp_ent, linkval, NULL, grp_ent, obj_ent, H5G_TARGET_NORMAL, nlinks, H5G_NAMEI_TRAVERSE, NULL))
 	HGOTO_ERROR (H5E_SYM, H5E_NOTFOUND, FAIL, "unable to follow symbolic link");
 
     /* Free the entry's names, we will use the original name for the object */
     H5G_free_ent_name(obj_ent);
 
     /* Restore previous name for object */
-    obj_ent->user_path = tmp_user_path;
-    tmp_user_path=NULL;
-    obj_ent->canon_path = tmp_canon_path;
-    tmp_canon_path=NULL;
+    obj_ent->user_path_r = tmp_user_path_r;
+    tmp_user_path_r=NULL;
+    obj_ent->canon_path_r = tmp_canon_path_r;
+    tmp_canon_path_r=NULL;
 	
 done:
     /* Error cleanup */
-    if(tmp_user_path)
-        H5MM_xfree(tmp_user_path);
-    if(tmp_canon_path)
-        H5MM_xfree(tmp_canon_path);
+    if(tmp_user_path_r)
+        H5RS_decr(tmp_user_path_r);
+    if(tmp_canon_path_r)
+        H5RS_decr(tmp_canon_path_r);
 
     /* Release cloned copy of group entry */
     H5G_free_ent_name(&tmp_grp_ent);
@@ -1475,6 +1518,7 @@ H5G_mkroot (H5F_t *f, H5G_entry_t *ent)
      */
     if (!ent) {
 	ent = &new_root;
+        HDmemset(ent, 0, sizeof(H5G_entry_t));
 	if (H5G_stab_create (f, 256, ent/*out*/)<0)
 	    HGOTO_ERROR (H5E_SYM, H5E_CANTINIT, FAIL, "unable to create root group");
 	if (1 != H5O_link (ent, 1))
@@ -1493,10 +1537,10 @@ H5G_mkroot (H5F_t *f, H5G_entry_t *ent)
     }
 
     /* Create the path names for the root group's entry */
-    ent->user_path=HDstrdup("/");
-    assert(ent->user_path);
-    ent->canon_path=HDstrdup("/");
-    assert(ent->canon_path);
+    ent->user_path_r=H5RS_create("/");
+    assert(ent->user_path_r);
+    ent->canon_path_r=H5RS_create("/");
+    assert(ent->canon_path_r);
     ent->user_path_hidden=0;
 
     /*
@@ -1504,7 +1548,7 @@ H5G_mkroot (H5F_t *f, H5G_entry_t *ent)
      * don't count the root group as an open object.  The root group will
      * never be closed.
      */
-    if (NULL==(f->shared->root_grp = H5FL_ALLOC (H5G_t,1)))
+    if (NULL==(f->shared->root_grp = H5FL_CALLOC (H5G_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     f->shared->root_grp->ent = *ent;
     f->shared->root_grp->nref = 1;
@@ -1544,11 +1588,8 @@ done:
 H5G_t *
 H5G_create(H5G_entry_t *loc, const char *name, size_t size_hint)
 {
-    const char	*rest = NULL;		/*the base name			*/
-    H5G_entry_t	grp_ent;		/*group containing new group	*/
-    char	_comp[1024];		/*name component		*/
-    size_t	nchars;			/*number of characters in compon*/
     H5G_t	*grp = NULL;		/*new group			*/
+    H5F_t       *file;                  /* File new group will be in    */
     H5G_t	*ret_value;		/* Return value */
 
     FUNC_ENTER_NOAPI(H5G_create, NULL);
@@ -1557,51 +1598,28 @@ H5G_create(H5G_entry_t *loc, const char *name, size_t size_hint)
     assert(loc);
     assert(name && *name);
 
-    /* lookup name */
-    if (0 == H5G_namei(loc, name, &rest, &grp_ent, NULL, H5G_TARGET_NORMAL, NULL))
-	HGOTO_ERROR(H5E_SYM, H5E_EXISTS, NULL, "already exists");
-    H5E_clear(); /*it's OK that we didn't find it */
-    assert(H5F_addr_defined(grp_ent.header));
-
-    /* should be one null-terminated component left */
-    rest = H5G_component(rest, &nchars);
-    assert(rest && *rest);
-    if (rest[nchars]) {
-	const char *t = H5G_component(rest+nchars, NULL);
-	if (t && *t) {
-	    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, NULL, "missing component");
-	} else if (nchars+1 > sizeof _comp) {
-	    HGOTO_ERROR(H5E_SYM, H5E_COMPLEN, NULL, "component is too long");
-	} else {
-	    /* null terminate */
-	    HDmemcpy(_comp, rest, nchars);
-	    _comp[nchars] = '\0';
-	    rest = _comp;
-	}
-    }
-    
     /* create an open group */
-    if (NULL==(grp = H5FL_ALLOC(H5G_t,1)))
+    if (NULL==(grp = H5FL_CALLOC(H5G_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-    if (H5G_stab_create(grp_ent.file, size_hint, &(grp->ent)/*out*/) < 0)
+
+    /* What file is the group being added to? */
+    if (NULL==(file=H5G_insertion_file(loc, name)))
+        HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, NULL, "unable to locate insertion point");
+
+    /* Create the group entry */
+    if (H5G_stab_create(file, size_hint, &(grp->ent)/*out*/) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, NULL, "can't create grp");
     
     /* insert child name into parent */
-    if (1!=H5O_link(&(grp->ent), 1))
-	HGOTO_ERROR(H5E_SYM, H5E_LINK, NULL, "link inc failure");
-    if (H5G_stab_insert(&grp_ent, rest, &(grp->ent)) < 0) {
-	H5O_close(&(grp->ent));
-	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, NULL, "can't insert");
-    }
+    if(H5G_insert(loc,name,&(grp->ent))<0)
+	HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, NULL, "can't insert group");
+
     grp->nref = 1;
 
     /* Set return value */
     ret_value=grp;
 
 done:
-    /* Free the group entry created from H5G_namei() */
-    H5G_free_ent_name(&grp_ent);
-    
     if(ret_value==NULL) {
         if(grp!=NULL)
             H5FL_FREE(H5G_t,grp);
@@ -1733,7 +1751,7 @@ H5G_open_oid(H5G_entry_t *ent)
     assert(ent);
 
     /* Open the object, making sure it's a group */
-    if (NULL==(grp = H5FL_ALLOC(H5G_t,1)))
+    if (NULL==(grp = H5FL_CALLOC(H5G_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* Copy over (take ownership) of the group entry object */
@@ -1894,10 +1912,6 @@ done:
 herr_t
 H5G_insert(H5G_entry_t *loc, const char *name, H5G_entry_t *ent)
 {
-    const char	*rest = NULL;	/*part of name not existing yet */
-    H5G_entry_t	grp;		/*entry for group to contain obj */
-    size_t	nchars;		/*number of characters in name	*/
-    char	_comp[1024];	/*name component		*/
     herr_t      ret_value=SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5G_insert, FAIL);
@@ -1908,44 +1922,18 @@ H5G_insert(H5G_entry_t *loc, const char *name, H5G_entry_t *ent)
     assert (ent);
 
     /*
-     * Look up the name -- it shouldn't exist yet.
+     * Lookup and insert the name -- it shouldn't exist yet.
      */
-    if (H5G_namei(loc, name, &rest, &grp, NULL, H5G_TARGET_NORMAL, NULL)>=0)
+    if (H5G_namei(loc, name, NULL, NULL, NULL, H5G_TARGET_NORMAL, NULL, H5G_NAMEI_INSERT, ent)<0)
 	HGOTO_ERROR(H5E_SYM, H5E_EXISTS, FAIL, "already exists");
-    H5E_clear(); /*it's OK that we didn't find it */
-    rest = H5G_component(rest, &nchars);
-
-    /*
-     * There should be one component left.  Make sure it's null
-     * terminated.
-     */
-    if (rest[nchars]) {
-	if (H5G_component(rest + nchars, NULL)) {
-	    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "component not found");
-	} else if (nchars + 1 > sizeof _comp) {
-	    HGOTO_ERROR(H5E_SYM, H5E_COMPLEN, FAIL, "component is too long");
-	} else {
-	    /* null terminate */
-	    HDmemcpy(_comp, rest, nchars);
-	    _comp[nchars] = '\0';
-	    rest = _comp;
-	}
-    }
 
     /*
      * Insert the object into a symbol table.
      */
     if (H5O_link(ent, 1) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_LINK, FAIL, "unable to increment hard link count");
-    if (H5G_stab_insert(&grp, rest, ent) < 0) {
-	H5O_link(ent, -1);
-	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to insert name");
-    }
 
 done:
-    /*Free the ID to name buffer */
-    H5G_free_ent_name(&grp);
-
     FUNC_LEAVE(ret_value);
 }
 
@@ -1989,7 +1977,7 @@ H5G_find(H5G_entry_t *loc, const char *name,
     assert (loc);
     assert (name && *name);
 
-    if (H5G_namei(loc, name, NULL, grp_ent, obj_ent, H5G_TARGET_NORMAL, NULL)<0)
+    if (H5G_namei(loc, name, NULL, grp_ent, obj_ent, H5G_TARGET_NORMAL, NULL, H5G_NAMEI_TRAVERSE, NULL)<0)
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "object not found");
 
 done:
@@ -2184,8 +2172,8 @@ H5G_link (H5G_entry_t *cur_loc, const char *cur_name, H5G_entry_t *new_loc,
              * Lookup the the new_name so we can get the group which will contain
              * the new entry.  The entry shouldn't exist yet.
              */
-            if (H5G_namei (new_loc, new_name, &rest, &grp_ent, NULL, 
-                            H5G_TARGET_NORMAL, NULL)>=0)
+            if (H5G_namei(new_loc, new_name, &rest, &grp_ent, NULL, 
+                            H5G_TARGET_NORMAL, NULL, H5G_NAMEI_TRAVERSE, NULL)>=0)
                 HGOTO_ERROR (H5E_SYM, H5E_EXISTS, FAIL, "already exists");
             H5E_clear (); /*it's okay that we didn't find it*/
             rest = H5G_component (rest, &nchars);
@@ -2239,7 +2227,7 @@ H5G_link (H5G_entry_t *cur_loc, const char *cur_name, H5G_entry_t *new_loc,
             break;
 
         case H5G_LINK_HARD:
-            if (H5G_namei(cur_loc, cur_name, NULL, NULL, &cur_obj, namei_flags, NULL)<0)
+            if (H5G_namei(cur_loc, cur_name, NULL, NULL, &cur_obj, namei_flags, NULL, H5G_NAMEI_TRAVERSE, NULL)<0)
                 HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "source object not found");
             if (H5G_insert (new_loc, new_name, &cur_obj)<0)
                 HGOTO_ERROR (H5E_SYM, H5E_CANTINIT, FAIL, "unable to create new name/link for object");
@@ -2339,8 +2327,8 @@ H5G_get_objinfo (H5G_entry_t *loc, const char *name, hbool_t follow_link,
     if (statbuf) HDmemset (statbuf, 0, sizeof *statbuf);
 
     /* Find the object's symbol table entry */
-    if (H5G_namei (loc, name, NULL, &grp_ent/*out*/, &obj_ent/*out*/,
-		   (unsigned)(follow_link?H5G_TARGET_NORMAL:H5G_TARGET_SLINK), NULL)<0)
+    if (H5G_namei(loc, name, NULL, &grp_ent/*out*/, &obj_ent/*out*/,
+		   (unsigned)(follow_link?H5G_TARGET_NORMAL:H5G_TARGET_SLINK), NULL, H5G_NAMEI_TRAVERSE, NULL)<0)
 	HGOTO_ERROR (H5E_SYM, H5E_NOTFOUND, FAIL, "unable to stat object");
 
     /*
@@ -2374,7 +2362,10 @@ H5G_get_objinfo (H5G_entry_t *loc, const char *name, hbool_t follow_link,
 	    statbuf->type = H5G_LINK;
 	    if (NULL==H5O_read(&obj_ent, H5O_MTIME, 0, &(statbuf->mtime))) {
 		H5E_clear();
-		statbuf->mtime = 0;
+                if (NULL==H5O_read(&obj_ent, H5O_MTIME_NEW, 0, &(statbuf->mtime))) {
+                    H5E_clear();
+                    statbuf->mtime = 0;
+                }
 	    }
 	    statbuf->type = H5G_get_type(&obj_ent);
 	    H5E_clear(); /*clear errors resulting from checking type*/
@@ -2450,7 +2441,7 @@ done:
 ssize_t 
 H5G_get_objname_by_idx(H5G_t *grp, hsize_t idx, char* name, size_t size)
 {
-    ssize_t		ret_value = FAIL;
+    ssize_t		ret_value;
     H5G_bt_ud3_t	udata;
     
     FUNC_ENTER_NOAPI(H5G_get_objname_by_idx, FAIL);
@@ -2472,10 +2463,10 @@ H5G_get_objname_by_idx(H5G_t *grp, hsize_t idx, char* name, size_t size)
             name[size-1]='\0';
     }
 
-    /* Free the duplicated name */
-    H5MM_xfree(udata.name);
-    
 done:
+    /* Free the duplicated name */
+    if(udata.name!=NULL)
+        H5MM_xfree(udata.name);
     FUNC_LEAVE(ret_value);
 }
 
@@ -2558,8 +2549,8 @@ H5G_linkval (H5G_entry_t *loc, const char *name, size_t size, char *buf/*out*/)
      * Get the symbol table entry for the link head and the symbol table
      * entry for the group in which the link head appears.
      */
-    if (H5G_namei (loc, name, NULL, &grp_ent/*out*/, &obj_ent/*out*/,
-		   H5G_TARGET_SLINK, NULL)<0)
+    if (H5G_namei(loc, name, NULL, &grp_ent/*out*/, &obj_ent/*out*/,
+		   H5G_TARGET_SLINK, NULL, H5G_NAMEI_TRAVERSE, NULL)<0)
 	HGOTO_ERROR (H5E_SYM, H5E_NOTFOUND, FAIL, "symbolic link was not found");
     if (H5G_CACHED_SLINK!=obj_ent.type)
 	HGOTO_ERROR (H5E_SYM, H5E_NOTFOUND, FAIL, "object is not a symbolic link");
@@ -2615,7 +2606,7 @@ H5G_set_comment(H5G_entry_t *loc, const char *name, const char *buf)
 
     /* Get the symbol table entry for the object */
     if (H5G_namei(loc, name, NULL, NULL, &obj_ent/*out*/, H5G_TARGET_NORMAL,
-		  NULL)<0)
+		  NULL, H5G_NAMEI_TRAVERSE, NULL)<0)
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "object not found");
 
     /* Remove the previous comment message if any */
@@ -2624,7 +2615,7 @@ H5G_set_comment(H5G_entry_t *loc, const char *name, const char *buf)
     /* Add the new message */
     if (buf && *buf) {
 	comment.s = H5MM_xstrdup(buf);
-	if (H5O_modify(&obj_ent, H5O_NAME, H5O_NEW_MESG, 0, &comment)<0)
+	if (H5O_modify(&obj_ent, H5O_NAME, H5O_NEW_MESG, 0, 1, &comment)<0)
 	    HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to set comment object header message");
 	H5O_reset(H5O_NAME, &comment);
     }
@@ -2669,7 +2660,7 @@ H5G_get_comment(H5G_entry_t *loc, const char *name, size_t bufsize, char *buf)
 
     /* Get the symbol table entry for the object */
     if (H5G_namei(loc, name, NULL, NULL, &obj_ent/*out*/, H5G_TARGET_NORMAL,
-		  NULL)<0)
+		  NULL, H5G_NAMEI_TRAVERSE, NULL)<0)
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "object not found");
 
     /* Get the message */
@@ -2717,6 +2708,7 @@ H5G_unlink(H5G_entry_t *loc, const char *name)
     size_t		len;
     const char		*base=NULL;
     H5G_stat_t		statbuf;        /* Info about object to unlink */
+    H5RS_str_t          *name_r;        /* Ref-counted version of name */
     herr_t      ret_value=SUCCEED;       /* Return value */
     
     FUNC_ENTER_NOAPI(H5G_unlink, FAIL);
@@ -2733,7 +2725,7 @@ H5G_unlink(H5G_entry_t *loc, const char *name)
 
     /* Get the entry for the group that contains the object to be unlinked */
     if (H5G_namei(loc, name, NULL, &grp_ent, &obj_ent,
-		  H5G_TARGET_SLINK|H5G_TARGET_MOUNT, NULL)<0)
+		  H5G_TARGET_SLINK|H5G_TARGET_MOUNT, NULL, H5G_NAMEI_TRAVERSE, NULL)<0)
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "object not found");
     if (!H5F_addr_defined(grp_ent.header))
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "no containing group specified");
@@ -2745,8 +2737,11 @@ H5G_unlink(H5G_entry_t *loc, const char *name)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to unlink name from symbol table");
 
     /* Search the open IDs and replace names for unlinked object */
-    if (H5G_replace_name(statbuf.type, &obj_ent, name, NULL, NULL, NULL, OP_UNLINK )<0)
+    name_r=H5RS_wrap(name);
+    assert(name_r);
+    if (H5G_replace_name(statbuf.type, &obj_ent, name_r, NULL, NULL, NULL, OP_UNLINK )<0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to replace name");
+    H5RS_decr(name_r);
 
 done:
     /* Free the ID to name buffers */
@@ -2785,6 +2780,8 @@ H5G_move(H5G_entry_t *src_loc, const char *src_name, H5G_entry_t *dst_loc,
     char		*linkval=NULL;
     size_t		lv_size=32;
     H5G_entry_t         obj_ent;        /* Object entry for object being moved */
+    H5RS_str_t         *src_name_r;     /* Ref-counted version of src name */
+    H5RS_str_t         *dst_name_r;     /* Ref-counted version of dest name */
     herr_t      ret_value=SUCCEED;      /* Return value */
     
     FUNC_ENTER_NOAPI(H5G_move, FAIL);
@@ -2825,10 +2822,16 @@ H5G_move(H5G_entry_t *src_loc, const char *src_name, H5G_entry_t *dst_loc,
      * This has to be done here because H5G_link and H5G_unlink have 
      * internal object entries, and do not modify the entries list
     */
-    if (H5G_namei (src_loc, src_name, NULL, NULL, &obj_ent, H5G_TARGET_NORMAL|H5G_TARGET_SLINK, NULL))
+    if (H5G_namei(src_loc, src_name, NULL, NULL, &obj_ent, H5G_TARGET_NORMAL|H5G_TARGET_SLINK, NULL, H5G_NAMEI_TRAVERSE, NULL))
 	HGOTO_ERROR (H5E_SYM, H5E_NOTFOUND, FAIL, "unable to follow symbolic link");
-    if (H5G_replace_name(sb.type, &obj_ent, src_name, src_loc, dst_name, dst_loc, OP_MOVE )<0)
+    src_name_r=H5RS_wrap(src_name);
+    assert(src_name_r);
+    dst_name_r=H5RS_wrap(dst_name);
+    assert(dst_name_r);
+    if (H5G_replace_name(sb.type, &obj_ent, src_name_r, src_loc, dst_name_r, dst_loc, OP_MOVE )<0)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to replace name ");
+    H5RS_decr(src_name_r);
+    H5RS_decr(dst_name_r);
     H5G_free_ent_name(&obj_ent);
 
     /* Remove the old name */
@@ -2864,37 +2867,53 @@ done:
 H5F_t *
 H5G_insertion_file(H5G_entry_t *loc, const char *name)
 {
-    const char	*rest;
-    H5G_entry_t	grp_ent;
-    size_t	size;
     H5F_t      *ret_value;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5G_insertion_file, NULL);
+
     assert(loc);
     assert(name && *name);
 
-    /*
-     * Look up the name to get the containing group and to make sure the name
-     * doesn't already exist.
+    /* Check if the location the object will be inserted into is part of a
+     * file mounting chain (either a parent or a child) and perform a more
+     * rigorous determination of the location's file (which traverses into
+     * mounted files, etc.).
      */
-    if (H5G_namei(loc, name, &rest, &grp_ent, NULL, H5G_TARGET_NORMAL, NULL)>=0)
-	HGOTO_ERROR(H5E_SYM, H5E_EXISTS, NULL, "name already exists");
-    H5E_clear();
+    if(H5F_has_mount(loc->file) || H5F_is_mount(loc->file)) {
+        const char	*rest;
+        H5G_entry_t	grp_ent;
+        size_t	size;
+
+        /*
+         * Look up the name to get the containing group and to make sure the name
+         * doesn't already exist.
+         */
+        if (H5G_namei(loc, name, &rest, &grp_ent, NULL, H5G_TARGET_NORMAL, NULL, H5G_NAMEI_TRAVERSE, NULL)>=0) {
+            H5G_free_ent_name(&grp_ent);
+            HGOTO_ERROR(H5E_SYM, H5E_EXISTS, NULL, "name already exists");
+        } /* end if */
+        H5E_clear();
+
+        /* Make sure only the last component wasn't resolved */
+        rest = H5G_component(rest, &size);
+        assert(*rest && size>0);
+        rest = H5G_component(rest+size, NULL);
+        if (*rest) {
+            H5G_free_ent_name(&grp_ent);
+            HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, NULL, "insertion point not found");
+        } /* end if */
 
-    /* Make sure only the last component wasn't resolved */
-    rest = H5G_component(rest, &size);
-    assert(*rest && size>0);
-    rest = H5G_component(rest+size, NULL);
-    if (*rest)
-	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, NULL, "insertion point not found");
+        /* Set return value */
+        ret_value=grp_ent.file;
 
-    /* Set return value */
-    ret_value=grp_ent.file;
+        /* Free the ID to name buffer */
+        H5G_free_ent_name(&grp_ent);
+    } /* end if */
+    else
+        /* Use the location's file */
+        ret_value=loc->file;
 
 done:
-    /* Free the ID to name buffer */
-    H5G_free_ent_name(&grp_ent);
-
     FUNC_LEAVE(ret_value);
 }
 
@@ -2967,10 +2986,14 @@ H5G_free_ent_name(H5G_entry_t *ent)
     /* Check args */
     assert(ent);
 
-    if(ent->user_path)
-        ent->user_path = H5MM_xfree(ent->user_path);
-    if(ent->canon_path)
-        ent->canon_path = H5MM_xfree(ent->canon_path);
+    if(ent->user_path_r) {
+        H5RS_decr(ent->user_path_r);
+        ent->user_path_r=NULL;
+    } /* end if */
+    if(ent->canon_path_r) {
+        H5RS_decr(ent->canon_path_r);
+        ent->canon_path_r=NULL;
+    } /* end if */
  
 done:
     FUNC_LEAVE(ret_value);
@@ -3001,8 +3024,8 @@ done:
  */
 herr_t
 H5G_replace_name( int type, H5G_entry_t *loc,
-    const char *src_name, H5G_entry_t *src_loc,
-    const char *dst_name, H5G_entry_t *dst_loc, H5G_names_op_t op )
+    H5RS_str_t *src_name, H5G_entry_t *src_loc,
+    H5RS_str_t *dst_name, H5G_entry_t *dst_loc, H5G_names_op_t op )
 {
     H5G_names_t names;          /* Structure to hold operation information for callback */
     unsigned search_group=0;    /* Flag to indicate that groups are to be searched */
@@ -3095,16 +3118,22 @@ done:
  *-------------------------------------------------------------------------
  */
 static htri_t
-H5G_common_path(const char *fullpath, const char *prefix)
+H5G_common_path(const H5RS_str_t *fullpath_r, const H5RS_str_t *prefix_r)
 {
+    const char *fullpath;       /* Pointer to actual fullpath string */
+    const char *prefix;         /* Pointer to actual prefix string */
     size_t  nchars1,nchars2;    /* Number of characters in components */
     htri_t ret_value=FALSE;     /* Return value */
   
     FUNC_ENTER_NOINIT(H5G_common_path);
   
     /* Get component of each name */
+    fullpath=H5RS_GET_STR(fullpath_r);
+    assert(fullpath);
     fullpath=H5G_component(fullpath,&nchars1);
     assert(fullpath);
+    prefix=H5RS_GET_STR(prefix_r);
+    assert(prefix);
     prefix=H5G_component(prefix,&nchars2);
     assert(prefix);
 
@@ -3199,12 +3228,11 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
         *-------------------------------------------------------------------------
         */
         case OP_MOUNT:
-            if(ent->file->mtab.parent && HDstrcmp(ent->user_path,ent->canon_path)) {
+            if(ent->file->mtab.parent && H5RS_cmp(ent->user_path_r,ent->canon_path_r)) {
                 /* Find the "top" file in the chain of mounted files */
                 top_ent_file=ent->file->mtab.parent;
-                while(top_ent_file->mtab.parent!=NULL) {
+                while(top_ent_file->mtab.parent!=NULL)
                     top_ent_file=top_ent_file->mtab.parent;
-                } /* end while */
             } /* end if */
             else
                 top_ent_file=ent->file;
@@ -3213,8 +3241,8 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
             if(top_ent_file->shared == names->loc->file->shared) {
                 /* Check if the source is along the entry's path */
                 /* (But not actually the entry itself) */
-                if(H5G_common_path(ent->user_path,names->src_name) &&
-                    HDstrcmp(ent->user_path,names->src_name)!=0) {
+                if(H5G_common_path(ent->user_path_r,names->src_name) &&
+                        H5RS_cmp(ent->user_path_r,names->src_name)!=0) {
                     /* Hide the user path */
                     ent->user_path_hidden++;
                 } /* end if */
@@ -3229,9 +3257,8 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
             if(ent->file->mtab.parent) {
                 /* Find the "top" file in the chain of mounted files for the entry */
                 top_ent_file=ent->file->mtab.parent;
-                while(top_ent_file->mtab.parent!=NULL) {
+                while(top_ent_file->mtab.parent!=NULL)
                     top_ent_file=top_ent_file->mtab.parent;
-                } /* end while */
             } /* end if */
             else
                 top_ent_file=ent->file;
@@ -3239,9 +3266,8 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
             if(names->loc->file->mtab.parent) {
                 /* Find the "top" file in the chain of mounted files for the location */
                 top_loc_file=names->loc->file->mtab.parent;
-                while(top_loc_file->mtab.parent!=NULL) {
+                while(top_loc_file->mtab.parent!=NULL)
                     top_loc_file=top_loc_file->mtab.parent;
-                } /* end while */
             } /* end if */
             else
                 top_loc_file=names->loc->file;
@@ -3249,7 +3275,7 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
             if(ent->user_path_hidden) {
                 /* If the ID's entry is not in the file we operated on, skip it */
                 if(top_ent_file->shared == top_loc_file->shared) {
-                    if(H5G_common_path(ent->user_path,names->src_name)) {
+                    if(H5G_common_path(ent->user_path_r,names->src_name)) {
                         /* Un-hide the user path */
                         ent->user_path_hidden--;
                     } /* end if */
@@ -3258,9 +3284,12 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
             else {
                 /* If the ID's entry is not in the file we operated on, skip it */
                 if(top_ent_file->shared == top_loc_file->shared) {
-                    if(ent->user_path && H5G_common_path(ent->user_path,names->src_name)) {
+                    if(ent->user_path_r && H5G_common_path(ent->user_path_r,names->src_name)) {
                         /* Free user path */
-                        ent->user_path=H5MM_xfree(ent->user_path);
+                        if(ent->user_path_r!=NULL) {
+                            H5RS_decr(ent->user_path_r);
+                            ent->user_path_r=NULL;
+                        } /* end if */
                     } /* end if */
                 } /* end if */
             } /* end else */
@@ -3276,16 +3305,22 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
                 /* Check if we are referring to the same object */
                 if(H5F_addr_eq(ent->header, names->loc->header)) {
                     /* Check if the object was opened with the same canonical path as the one being moved */
-                    if(HDstrcmp(ent->canon_path,names->loc->canon_path)==0) {
+                    if(H5RS_cmp(ent->canon_path_r,names->loc->canon_path_r)==0) {
                         /* Free user path */
-                        ent->user_path=H5MM_xfree(ent->user_path);
+                        if(ent->user_path_r!=NULL) {
+                            H5RS_decr(ent->user_path_r);
+                            ent->user_path_r=NULL;
+                        } /* end if */
                     } /* end if */
                 } /* end if */
                 else {
                     /* Check if the location being unlinked is in the canonical path for the current object */
-                    if(H5G_common_path(ent->canon_path,names->loc->canon_path)) {
+                    if(H5G_common_path(ent->canon_path_r,names->loc->canon_path_r)) {
                         /* Free user path */
-                        ent->user_path=H5MM_xfree(ent->user_path);
+                        if(ent->user_path_r!=NULL) {
+                            H5RS_decr(ent->user_path_r);
+                            ent->user_path_r=NULL;
+                        } /* end if */
                     } /* end if */
                 } /* end else */
             } /* end if */
@@ -3298,90 +3333,116 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
         case OP_MOVE: /* H5Gmove case, check for relative names case */
             /* If the ID's entry is not in the file we operated on, skip it */
             if(ent->file->shared == names->loc->file->shared) {
-                char *src_path;         /* Full user path of source name */
-                char *dst_path;         /* Full user path of destination name */
-                char *canon_src_path;   /* Pointer to canonical part of source path */
-                char *canon_dst_path;   /* Pointer to canonical part of destination path */
+                H5RS_str_t *src_path_r; /* Full user path of source name */
+                H5RS_str_t *dst_path_r; /* Full user path of destination name */
+                H5RS_str_t *canon_src_path_r;   /* Copy of canonical part of source path */
+                H5RS_str_t *canon_dst_path_r;   /* Copy of canonical part of destination path */
 
                 /* Make certain that the source and destination names are full (not relative) paths */
-                if(*(names->src_name)!='/') {
+                if(*(H5RS_GET_STR(names->src_name))!='/') {
+                    const char *src_name;         /* Pointer to raw string of src_name */
+                    char *src_path;         /* Full user path of source name */
+                    const char *src_user_path;    /* Pointer to raw string of src path */
                     size_t src_path_len;    /* Length of the source path */
                     unsigned need_sep;      /* Flag to indicate if separator is needed */
 
+                    /* Get the pointer to the raw src user path */
+                    src_user_path=H5RS_GET_STR(names->src_loc->user_path_r);
+
                     /* Get the length of the name for the source group's user path */
-                    src_path_len=HDstrlen(names->src_loc->user_path);
+                    src_path_len=HDstrlen(src_user_path);
 
                     /* Determine if there is a trailing separator in the name */
-                    if(names->src_loc->user_path[src_path_len-1]=='/')
+                    if(src_user_path[src_path_len-1]=='/')
                         need_sep=0;
                     else
                         need_sep=1;
 
+                    /* Get the pointer to the raw src user path */
+                    src_name=H5RS_GET_STR(names->src_name);
+
                     /* Add in the length needed for the '/' separator and the relative path */
-                    src_path_len+=HDstrlen(names->src_name)+need_sep;
+                    src_path_len+=HDstrlen(src_name)+need_sep;
 
                     /* Allocate space for the path */
-                    if(NULL==(src_path = H5MM_malloc(src_path_len+1)))
+                    if(NULL==(src_path = H5FL_BLK_MALLOC(str_buf,src_path_len+1)))
                         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
-                    HDstrcpy(src_path,names->src_loc->user_path);
+                    HDstrcpy(src_path,src_user_path);
                     if(need_sep)
                         HDstrcat(src_path,"/");
-                    HDstrcat(src_path,names->src_name);
+                    HDstrcat(src_path,src_name);
+
+                    /* Create reference counted string for src path */
+                    src_path_r=H5RS_own(src_path);
                 } /* end if */
                 else
-                    src_path=HDstrdup(names->src_name);
-                if(*(names->dst_name)!='/') {
-                    size_t dst_path_len;        /* Length of the destination path */
+                    src_path_r=H5RS_dup(names->src_name);
+                if(*(H5RS_GET_STR(names->dst_name))!='/') {
+                    const char *dst_name;         /* Pointer to raw string of dst_name */
+                    char *dst_path;         /* Full user path of destination name */
+                    const char *dst_user_path;    /* Pointer to raw string of dst path */
+                    size_t dst_path_len;    /* Length of the destination path */
                     unsigned need_sep;      /* Flag to indicate if separator is needed */
 
+                    /* Get the pointer to the raw dst user path */
+                    dst_user_path=H5RS_GET_STR(names->dst_loc->user_path_r);
+
                     /* Get the length of the name for the destination group's user path */
-                    dst_path_len=HDstrlen(names->dst_loc->user_path);
+                    dst_path_len=HDstrlen(dst_user_path);
 
                     /* Determine if there is a trailing separator in the name */
-                    if(names->dst_loc->user_path[dst_path_len-1]=='/')
+                    if(dst_user_path[dst_path_len-1]=='/')
                         need_sep=0;
                     else
                         need_sep=1;
 
+                    /* Get the pointer to the raw dst user path */
+                    dst_name=H5RS_GET_STR(names->dst_name);
+
                     /* Add in the length needed for the '/' separator and the relative path */
-                    dst_path_len+=HDstrlen(names->dst_name)+need_sep;
+                    dst_path_len+=HDstrlen(dst_name)+need_sep;
 
                     /* Allocate space for the path */
-                    if(NULL==(dst_path = H5MM_malloc(dst_path_len+1)))
+                    if(NULL==(dst_path = H5FL_BLK_MALLOC(str_buf,dst_path_len+1)))
                         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
-                    HDstrcpy(dst_path,names->dst_loc->user_path);
+                    HDstrcpy(dst_path,dst_user_path);
                     if(need_sep)
                         HDstrcat(dst_path,"/");
-                    HDstrcat(dst_path,names->dst_name);
+                    HDstrcat(dst_path,dst_name);
+
+                    /* Create reference counted string for dst path */
+                    dst_path_r=H5RS_own(dst_path);
                 } /* end if */
                 else
-                    dst_path=HDstrdup(names->dst_name);
+                    dst_path_r=H5RS_dup(names->dst_name);
 
                 /* Get the canonical parts of the source and destination names */
 
                 /* Check if the object being moved was accessed through a mounted file */
-                if(HDstrcmp(names->loc->user_path,names->loc->canon_path)!=0) {
+                if(H5RS_cmp(names->loc->user_path_r,names->loc->canon_path_r)!=0) {
                     size_t non_canon_name_len;   /* Length of non-canonical part of name */
 
                     /* Get current string lengths */
-                    non_canon_name_len=HDstrlen(names->loc->user_path)-HDstrlen(names->loc->canon_path);
+                    non_canon_name_len=H5RS_len(names->loc->user_path_r)-H5RS_len(names->loc->canon_path_r);
 
-                    canon_src_path=src_path+non_canon_name_len;
-                    canon_dst_path=dst_path+non_canon_name_len;
+                    canon_src_path_r=H5RS_create(H5RS_GET_STR(src_path_r)+non_canon_name_len);
+                    canon_dst_path_r=H5RS_create(H5RS_GET_STR(dst_path_r)+non_canon_name_len);
                 } /* end if */
                 else {
-                    canon_src_path=src_path;
-                    canon_dst_path=dst_path;
+                    canon_src_path_r=H5RS_dup(src_path_r);
+                    canon_dst_path_r=H5RS_dup(dst_path_r);
                 } /* end else */
 
                 /* Check if the link being changed in the file is along the canonical path for this object */
-                if(H5G_common_path(ent->canon_path,canon_src_path)) {
+                if(H5G_common_path(ent->canon_path_r,canon_src_path_r)) {
                     size_t user_dst_len;    /* Length of destination user path */
                     size_t canon_dst_len;   /* Length of destination canonical path */
-                    char *old_user_path;    /* Pointer to previous user path */
-                    char *tail_path;    /* Pointer to "tail" of path */
+                    const char *old_user_path;    /* Pointer to previous user path */
+                    char *new_user_path;    /* Pointer to new user path */
+                    char *new_canon_path;   /* Pointer to new canonical path */
+                    const char *tail_path;  /* Pointer to "tail" of path */
                     size_t tail_len;    /* Pointer to "tail" of path */
                     char *src_canon_prefix;     /* Pointer to source canonical path prefix of component which is moving */
                     size_t src_canon_prefix_len;/* Length of the source canonical path prefix */
@@ -3391,6 +3452,12 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
                     size_t user_prefix_len; /* Length of the user path prefix */
                     char *src_comp;     /* The source name of the component which is actually changing */
                     char *dst_comp;     /* The destination name of the component which is actually changing */
+                    const char *canon_src_path;   /* pointer to canonical part of source path */
+                    const char *canon_dst_path;   /* pointer to canonical part of destination path */
+
+                    /* Get the pointers to the raw strings */
+                    canon_src_path=H5RS_GET_STR(canon_src_path_r);
+                    canon_dst_path=H5RS_GET_STR(canon_dst_path_r);
 
                     /* Get the source & destination components */
                     src_comp=HDstrrchr(canon_src_path,'/');
@@ -3411,46 +3478,48 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
                     HDstrncpy(dst_canon_prefix,canon_dst_path,dst_canon_prefix_len);
                     dst_canon_prefix[dst_canon_prefix_len]='\0';
 
+                    /* Hold this for later use */
+                    old_user_path=H5RS_GET_STR(ent->user_path_r);
+
                     /* Find the user prefix for the entry */
-                    user_prefix_len=HDstrlen(ent->user_path)-HDstrlen(ent->canon_path);
+                    user_prefix_len=HDstrlen(old_user_path)-H5RS_len(ent->canon_path_r);
                     if(NULL==(user_prefix = H5MM_malloc(user_prefix_len+1)))
                         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
-                    HDstrncpy(user_prefix,ent->user_path,user_prefix_len);
+                    HDstrncpy(user_prefix,old_user_path,user_prefix_len);
                     user_prefix[user_prefix_len]='\0';
 
-                    /* Hold this for later use */
-                    old_user_path=ent->user_path;
-
                     /* Set the tail path info */
                     tail_path=old_user_path+user_prefix_len+src_canon_prefix_len+HDstrlen(src_comp);
                     tail_len=HDstrlen(tail_path);
 
-                    /* Free the old canonical path */
-                    H5MM_xfree(ent->canon_path);
-
                     /* Get the length of the destination paths */
                     user_dst_len=user_prefix_len+dst_canon_prefix_len+HDstrlen(dst_comp)+tail_len;
                     canon_dst_len=dst_canon_prefix_len+HDstrlen(dst_comp)+tail_len;
 
                     /* Allocate space for the new user path */
-                    if(NULL==(ent->user_path = H5MM_malloc(user_dst_len+1)))
+                    if(NULL==(new_user_path = H5FL_BLK_MALLOC(str_buf,user_dst_len+1)))
                         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
                     
                     /* Allocate space for the new canonical path */
-                    if(NULL==(ent->canon_path = H5MM_malloc(canon_dst_len+1)))
+                    if(NULL==(new_canon_path = H5FL_BLK_MALLOC(str_buf,canon_dst_len+1)))
                         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
                     
                     /* Create the new names */
-                    HDstrcpy(ent->user_path,user_prefix);
-                    HDstrcat(ent->user_path,dst_canon_prefix);
-                    HDstrcat(ent->user_path,dst_comp);
-                    HDstrcat(ent->user_path,tail_path);
-                    HDstrcpy(ent->canon_path,dst_canon_prefix);
-                    HDstrcat(ent->canon_path,dst_comp);
-                    HDstrcat(ent->canon_path,tail_path);
-
-                    /* Free the old user path */
-                    H5MM_xfree(old_user_path);
+                    HDstrcpy(new_user_path,user_prefix);
+                    HDstrcat(new_user_path,dst_canon_prefix);
+                    HDstrcat(new_user_path,dst_comp);
+                    HDstrcat(new_user_path,tail_path);
+                    HDstrcpy(new_canon_path,dst_canon_prefix);
+                    HDstrcat(new_canon_path,dst_comp);
+                    HDstrcat(new_canon_path,tail_path);
+
+                    /* Release the old user & canonical paths */
+                    H5RS_decr(ent->user_path_r);
+                    H5RS_decr(ent->canon_path_r);
+
+                    /* Take ownership of the new user & canonical paths */
+                    ent->user_path_r=H5RS_own(new_user_path);
+                    ent->canon_path_r=H5RS_own(new_canon_path);
 
                     /* Free the extra paths allocated */
                     H5MM_xfree(src_canon_prefix);
@@ -3460,8 +3529,10 @@ H5G_replace_ent(void *obj_ptr, hid_t obj_id, const void *key)
 
 
                 /* Free the extra paths allocated */
-                H5MM_xfree(src_path);
-                H5MM_xfree(dst_path);
+                H5RS_decr(src_path_r);
+                H5RS_decr(dst_path_r);
+                H5RS_decr(canon_src_path_r);
+                H5RS_decr(canon_dst_path_r);
             } /* end if */
             break;
 
diff --git a/src/H5Gent.c b/src/H5Gent.c
index 4e0a4f9..3bf1a58 100644
--- a/src/H5Gent.c
+++ b/src/H5Gent.c
@@ -357,6 +357,9 @@ done:
  *              of the functions in the library.
  *          - Added 'depth' parameter to determine how much of the group
  *              entry structure we want to copy.  The new depths are:
+ *                  H5G_COPY_NULL - Copy all the fields from the
+ *                      source to the destination, but set the destination's
+ *                      user path and canonical path to NULL.
  *                  H5G_COPY_LIMITED - Copy all the fields from the
  *                      source to the destination, except for the user path
  *                      field, keeping it the same as its
@@ -373,19 +376,19 @@ done:
 herr_t
 H5G_ent_copy(H5G_entry_t *dst, const H5G_entry_t *src, H5G_ent_copy_depth_t depth)
 {
-    char *tmp_user_path=NULL;   /* Temporary string pointers for entry's user path */
+    H5RS_str_t *tmp_user_path_r=NULL;   /* Temporary string pointer for entry's user path */
     herr_t ret_value=SUCCEED;   /* Return value */
 
     FUNC_ENTER_NOAPI(H5G_ent_copy, FAIL);
 
-    /* check arguments */
-    assert( src );
-    assert( dst );
+    /* Check arguments */
+    assert(src);
+    assert(dst);
 
     /* If the depth is "very shallow", keep the old entry's user path */
     if(depth==H5G_COPY_LIMITED) {
-        tmp_user_path=dst->user_path;
-        H5MM_xfree(dst->canon_path);
+        tmp_user_path_r=dst->user_path_r;
+        H5RS_decr(dst->canon_path_r);
     } /* end if */
 
     /* Copy the top level information */
@@ -393,11 +396,14 @@ H5G_ent_copy(H5G_entry_t *dst, const H5G_entry_t *src, H5G_ent_copy_depth_t dept
 
     /* Deep copy the names */
     if(depth==H5G_COPY_DEEP) {
-        dst->user_path=H5MM_xstrdup(src->user_path);
-        dst->canon_path=H5MM_xstrdup(src->canon_path);
+        dst->user_path_r=H5RS_dup(src->user_path_r);
+        dst->canon_path_r=H5RS_dup(src->canon_path_r);
     } else if(depth==H5G_COPY_LIMITED) {
-        dst->user_path=tmp_user_path;
-        dst->canon_path=H5MM_xstrdup(src->canon_path);
+        dst->user_path_r=tmp_user_path_r;
+        dst->canon_path_r=H5RS_dup(src->canon_path_r);
+    } else if(depth==H5G_COPY_NULL) {
+        dst->user_path_r=NULL;
+        dst->canon_path_r=NULL;
     } /* end if */
 
 done:
diff --git a/src/H5Gnode.c b/src/H5Gnode.c
index 98fde41..d850910 100644
--- a/src/H5Gnode.c
+++ b/src/H5Gnode.c
@@ -224,7 +224,7 @@ H5G_node_size(H5F_t *f)
     FUNC_ENTER_NOINIT(H5G_node_size);
 
     FUNC_LEAVE(H5G_NODE_SIZEOF_HDR(f) +
-	(2 * H5G_node_k(f)) * H5G_SIZEOF_ENTRY(f));
+	(2 * H5F_SYM_LEAF_K(f)) * H5G_SIZEOF_ENTRY(f));
 }
 
 
@@ -267,13 +267,13 @@ H5G_node_create(H5F_t *f, H5B_ins_t UNUSED op, void *_lt_key,
     assert(f);
     assert(H5B_INS_FIRST == op);
 
-    if (NULL==(sym = H5FL_ALLOC(H5G_node_t,1)))
+    if (NULL==(sym = H5FL_CALLOC(H5G_node_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     size = H5G_node_size(f);
     if (HADDR_UNDEF==(*addr_p=H5MF_alloc(f, H5FD_MEM_BTREE, size)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "unable to allocate file space");
     sym->dirty = TRUE;
-    sym->entry = H5FL_ARR_ALLOC(H5G_entry_t,(2*H5G_node_k(f)),1);
+    sym->entry = H5FL_ARR_CALLOC(H5G_entry_t,(2*H5F_SYM_LEAF_K(f)));
     if (NULL==sym->entry)
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     if (H5AC_set(f, H5AC_SNODE, *addr_p, sym) < 0)
@@ -366,7 +366,7 @@ H5G_node_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5G_node_
         size = H5G_node_size(f);
 
         /* Allocate temporary buffer */
-        if ((buf=H5FL_BLK_ALLOC(symbol_node,size, 0))==NULL)
+        if ((buf=H5FL_BLK_MALLOC(symbol_node,size))==NULL)
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
         p=buf;
 
@@ -401,10 +401,6 @@ H5G_node_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5G_node_
      * preempted from the cache.
      */
     if (destroy) {
-        /* Free the ID to name buffer */
-        for (i=0; i<sym->nsyms; i++)
-            H5G_free_ent_name(&(sym->entry[i]));
-
 	sym->entry = H5FL_ARR_FREE(H5G_entry_t,sym->entry);
 	H5FL_FREE(H5G_node_t,sym);
     }
@@ -460,11 +456,11 @@ H5G_node_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED _udata1
      * Initialize variables.
      */
     size = H5G_node_size(f);
-    if ((buf=H5FL_BLK_ALLOC(symbol_node,size,0))==NULL)
+    if ((buf=H5FL_BLK_MALLOC(symbol_node,size))==NULL)
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for symbol table node");
     p=buf;
-    if (NULL==(sym = H5FL_ALLOC(H5G_node_t,1)) ||
-            NULL==(sym->entry=H5FL_ARR_ALLOC(H5G_entry_t,(2*H5G_node_k(f)),1)))
+    if (NULL==(sym = H5FL_CALLOC(H5G_node_t)) ||
+            NULL==(sym->entry=H5FL_ARR_CALLOC(H5G_entry_t,(2*H5F_SYM_LEAF_K(f)))))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     if (H5F_block_read(f, H5FD_MEM_BTREE, addr, size, dxpl_id, buf) < 0)
 	HGOTO_ERROR(H5E_SYM, H5E_READERROR, NULL, "unable to read symbol table node");
@@ -534,6 +530,7 @@ H5G_node_cmp2(H5F_t *f, void *_lt_key, void *_udata, void *_rt_key)
     H5G_node_key_t	   *lt_key = (H5G_node_key_t *) _lt_key;
     H5G_node_key_t	   *rt_key = (H5G_node_key_t *) _rt_key;
     const char		   *s1, *s2;
+    const char		   *base;           /* Base of heap */
     int		    ret_value;
 
     FUNC_ENTER_NOAPI(H5G_node_cmp2, FAIL);
@@ -542,11 +539,14 @@ H5G_node_cmp2(H5F_t *f, void *_lt_key, void *_udata, void *_rt_key)
     assert(lt_key);
     assert(rt_key);
 
-    if (NULL == (s1 = H5HL_peek(f, udata->heap_addr, lt_key->offset)))
-	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to read symbol name");
-    if (NULL == (s2 = H5HL_peek(f, udata->heap_addr, rt_key->offset)))
+    /* Get base address of heap */
+    if (NULL == (base = H5HL_peek(f, udata->heap_addr, 0)))
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to read symbol name");
 
+    /* Get pointers to string names */
+    s1=base+lt_key->offset;
+    s2=base+rt_key->offset;
+
     /* Set return value */
     ret_value = HDstrcmp(s1, s2);
 
@@ -585,23 +585,26 @@ done:
 static int
 H5G_node_cmp3(H5F_t *f, void *_lt_key, void *_udata, void *_rt_key)
 {
-    H5G_bt_ud1_t	   *udata = (H5G_bt_ud1_t *) _udata;
-    H5G_node_key_t	   *lt_key = (H5G_node_key_t *) _lt_key;
-    H5G_node_key_t	   *rt_key = (H5G_node_key_t *) _rt_key;
-    const char		   *s;
-    int                    ret_value=0;       /* Return value */
+    H5G_bt_ud1_t	*udata = (H5G_bt_ud1_t *) _udata;
+    H5G_node_key_t	*lt_key = (H5G_node_key_t *) _lt_key;
+    H5G_node_key_t	*rt_key = (H5G_node_key_t *) _rt_key;
+    const char		*s;
+    const char          *base;              /* Base of heap */
+    int                  ret_value=0;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5G_node_cmp3, FAIL);
 
-    /* left side */
-    if (NULL == (s = H5HL_peek(f, udata->heap_addr, lt_key->offset)))
+    /* Get base address of heap */
+    if (NULL == (base = H5HL_peek(f, udata->heap_addr, 0)))
 	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to read symbol name");
+
+    /* left side */
+    s=base+lt_key->offset;
     if (HDstrcmp(udata->name, s) <= 0)
 	HGOTO_DONE(-1);
 
     /* right side */
-    if (NULL == (s = H5HL_peek(f, udata->heap_addr, rt_key->offset)))
-	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to read symbol name");
+    s=base+rt_key->offset;
     if (HDstrcmp(udata->name, s) > 0)
 	HGOTO_DONE(1);
 
@@ -647,6 +650,7 @@ H5G_node_found(H5F_t *f, haddr_t addr, const void UNUSED *_lt_key,
     H5G_node_t		*sn = NULL;
     int		lt = 0, idx = 0, rt, cmp = 1;
     const char		*s;
+    const char          *base;           /* Base of heap */
     herr_t      ret_value=SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5G_node_found, FAIL);
@@ -664,14 +668,17 @@ H5G_node_found(H5F_t *f, haddr_t addr, const void UNUSED *_lt_key,
     if (NULL == (sn = H5AC_protect(f, H5AC_SNODE, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, FAIL, "unable to protect symbol table node");
 
+    /* Get base address of heap */
+    if (NULL == (base = H5HL_peek(f, bt_udata->heap_addr, 0)))
+	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to read symbol name");
+
     /*
      * Binary search.
      */
     rt = sn->nsyms;
     while (lt < rt && cmp) {
 	idx = (lt + rt) / 2;
-	if (NULL == (s = H5HL_peek(f, bt_udata->heap_addr, sn->entry[idx].name_off)))
-	    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, FAIL, "unable to read symbol name");
+        s=base+sn->entry[idx].name_off;
 	cmp = HDstrcmp(bt_udata->name, s);
 
 	if (cmp < 0) {
@@ -750,10 +757,11 @@ H5G_node_insert(H5F_t *f, haddr_t addr, void UNUSED *_lt_key,
     H5G_node_t		*sn = NULL, *snrt = NULL;
     size_t		offset;			/*offset of name in heap */
     const char		*s;
+    const char          *base;           /* Base of heap */
     int		idx = -1, cmp = 1;
     int		lt = 0, rt;		/*binary search cntrs	*/
-    H5B_ins_t		ret_value = H5B_INS_ERROR;
     H5G_node_t		*insert_into = NULL;	/*node that gets new entry*/
+    H5B_ins_t		ret_value = H5B_INS_ERROR;
 
     FUNC_ENTER_NOAPI(H5G_node_insert, H5B_INS_ERROR);
 
@@ -773,14 +781,17 @@ H5G_node_insert(H5F_t *f, haddr_t addr, void UNUSED *_lt_key,
     if (NULL == (sn = H5AC_protect(f, H5AC_SNODE, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, H5B_INS_ERROR, "unable to protect symbol table node");
 
+    /* Get base address of heap */
+    if (NULL == (base = H5HL_peek(f, bt_udata->heap_addr, 0)))
+	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, H5B_INS_ERROR, "unable to read symbol name");
+
     /*
      * Where does the new symbol get inserted?	We use a binary search.
      */
     rt = sn->nsyms;
     while (lt < rt) {
 	idx = (lt + rt) / 2;
-	if (NULL == (s = H5HL_peek(f, bt_udata->heap_addr, sn->entry[idx].name_off)))
-	    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, H5B_INS_ERROR, "unable to read symbol name");
+        s=base+sn->entry[idx].name_off;
 	if (0 == (cmp = HDstrcmp(bt_udata->name, s))) /*already present */
 	    HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, H5B_INS_ERROR, "symbol is already present in symbol table");
 	if (cmp < 0) {
@@ -799,7 +810,7 @@ H5G_node_insert(H5F_t *f, haddr_t addr, void UNUSED *_lt_key,
     bt_udata->ent.name_off = offset;
     if (0==offset || (size_t)(-1)==offset)
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINSERT, H5B_INS_ERROR, "unable to insert symbol name into heap");
-    if ((size_t)(sn->nsyms) >= 2*H5G_node_k(f)) {
+    if ((size_t)(sn->nsyms) >= 2*H5F_SYM_LEAF_K(f)) {
 	/*
 	 * The node is full.  Split it into a left and right
 	 * node and return the address of the new right node (the
@@ -811,31 +822,31 @@ H5G_node_insert(H5F_t *f, haddr_t addr, void UNUSED *_lt_key,
 	if (H5G_node_create(f, H5B_INS_FIRST, NULL, NULL, NULL,
 			    new_node_p/*out*/)<0)
 	    HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, H5B_INS_ERROR, "unable to split symbol table node");
-	if (NULL==(snrt=H5AC_find(f, H5AC_SNODE, *new_node_p, NULL, NULL)))
+	if (NULL==(snrt=H5AC_find_f(f, H5AC_SNODE, *new_node_p, NULL, NULL)))
 	    HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, H5B_INS_ERROR, "unable to split symbol table node");
-	HDmemcpy(snrt->entry, sn->entry + H5G_node_k(f),
-		 H5G_node_k(f) * sizeof(H5G_entry_t));
-	snrt->nsyms = H5G_node_k(f);
+	HDmemcpy(snrt->entry, sn->entry + H5F_SYM_LEAF_K(f),
+		 H5F_SYM_LEAF_K(f) * sizeof(H5G_entry_t));
+	snrt->nsyms = H5F_SYM_LEAF_K(f);
 	snrt->dirty = TRUE;
 
 	/* The left node */
-	HDmemset(sn->entry + H5G_node_k(f), 0,
-		 H5G_node_k(f) * sizeof(H5G_entry_t));
-	sn->nsyms = H5G_node_k(f);
+	HDmemset(sn->entry + H5F_SYM_LEAF_K(f), 0,
+		 H5F_SYM_LEAF_K(f) * sizeof(H5G_entry_t));
+	sn->nsyms = H5F_SYM_LEAF_K(f);
 	sn->dirty = TRUE;
 
 	/* The middle key */
 	md_key->offset = sn->entry[sn->nsyms - 1].name_off;
 
 	/* Where to insert the new entry? */
-	if (idx <= (int)H5G_node_k(f)) {
+	if (idx <= (int)H5F_SYM_LEAF_K(f)) {
 	    insert_into = sn;
-	    if (idx == (int)H5G_node_k(f))
+	    if (idx == (int)H5F_SYM_LEAF_K(f))
 		md_key->offset = offset;
 	} else {
-	    idx -= H5G_node_k(f);
+	    idx -= H5F_SYM_LEAF_K(f);
 	    insert_into = snrt;
-	    if (idx == (int)H5G_node_k (f)) {
+	    if (idx == (int)H5F_SYM_LEAF_K (f)) {
 		rt_key->offset = offset;
 		*rt_key_changed = TRUE;
 	    }
@@ -856,7 +867,7 @@ H5G_node_insert(H5F_t *f, haddr_t addr, void UNUSED *_lt_key,
     HDmemmove(insert_into->entry + idx + 1,
 	      insert_into->entry + idx,
 	      (insert_into->nsyms - idx) * sizeof(H5G_entry_t));
-    H5G_ent_copy(&(insert_into->entry[idx]), &(bt_udata->ent),H5G_COPY_DEEP);
+    H5G_ent_copy(&(insert_into->entry[idx]), &(bt_udata->ent),H5G_COPY_NULL);
     insert_into->entry[idx].dirty = TRUE;
     insert_into->nsyms += 1;
 
@@ -905,9 +916,10 @@ H5G_node_remove(H5F_t *f, haddr_t addr, void *_lt_key/*in,out*/,
     H5G_node_key_t	*rt_key = (H5G_node_key_t*)_rt_key;
     H5G_bt_ud1_t	*bt_udata = (H5G_bt_ud1_t*)_udata;
     H5G_node_t		*sn = NULL;
-    H5B_ins_t		ret_value = H5B_INS_ERROR;
     int		lt=0, rt, idx=0, cmp=1;
     const char		*s = NULL;
+    const char          *base;              /* Base of heap */
+    H5B_ins_t		ret_value = H5B_INS_ERROR;
 
     FUNC_ENTER_NOAPI(H5G_node_remove, H5B_INS_ERROR);
 
@@ -922,13 +934,15 @@ H5G_node_remove(H5F_t *f, haddr_t addr, void *_lt_key/*in,out*/,
     if (NULL==(sn=H5AC_protect(f, H5AC_SNODE, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, H5B_INS_ERROR, "unable to protect symbol table node");
 
+    /* Get base address of heap */
+    if (NULL == (base = H5HL_peek(f, bt_udata->heap_addr, 0)))
+	HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, H5B_INS_ERROR, "unable to read symbol name");
+
     /* Find the name with a binary search */
     rt = sn->nsyms;
     while (lt<rt && cmp) {
 	idx = (lt+rt)/2;
-	if (NULL==(s=H5HL_peek(f, bt_udata->heap_addr,
-			       sn->entry[idx].name_off)))
-	    HGOTO_ERROR(H5E_SYM, H5E_NOTFOUND, H5B_INS_ERROR, "unable to read symbol name");
+        s=base+sn->entry[idx].name_off;
 	cmp = HDstrcmp(bt_udata->name, s);
 	if (cmp<0) {
 	    rt = idx;
@@ -941,8 +955,7 @@ H5G_node_remove(H5F_t *f, haddr_t addr, void *_lt_key/*in,out*/,
 
     if (H5G_CACHED_SLINK==sn->entry[idx].type) {
 	/* Remove the symbolic link value */
-	if ((s=H5HL_peek(f, bt_udata->heap_addr,
-			 sn->entry[idx].cache.slink.lval_offset)))
+	if ((s=H5HL_peek(f, bt_udata->heap_addr, sn->entry[idx].cache.slink.lval_offset)))
 	    H5HL_remove(f, bt_udata->heap_addr, sn->entry[idx].cache.slink.lval_offset, HDstrlen(s)+1);
 	H5E_clear(); /*no big deal*/
     } else {
@@ -957,9 +970,6 @@ H5G_node_remove(H5F_t *f, haddr_t addr, void *_lt_key/*in,out*/,
 	H5HL_remove(f, bt_udata->heap_addr, sn->entry[idx].name_off, HDstrlen(s)+1);
     H5E_clear(); /*no big deal*/
 
-    /* Free the ID to name buffer for the entry being squeezed out */
-    H5G_free_ent_name(sn->entry+idx);
-
     /* Remove the entry from the symbol table node */
     if (1==sn->nsyms) {
 	/*
@@ -1070,7 +1080,7 @@ H5G_node_iterate (H5F_t *f, void UNUSED *_lt_key, haddr_t addr,
      * Save information about the symbol table node since we can't lock it
      * because we're about to call an application function.
      */
-    if (NULL == (sn = H5AC_find(f, H5AC_SNODE, addr, NULL, NULL)))
+    if (NULL == (sn = H5AC_find_f(f, H5AC_SNODE, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, H5B_ITER_ERROR, "unable to load symbol table node");
     nsyms = sn->nsyms;
     if (NULL==(name_off = H5MM_malloc (nsyms*sizeof(name_off[0]))))
@@ -1082,12 +1092,11 @@ H5G_node_iterate (H5F_t *f, void UNUSED *_lt_key, haddr_t addr,
     /*
      * Iterate over the symbol table node entries.
      */
-    for (i=0, ret_value=0; i<nsyms && 0==ret_value; i++) {
+    for (i=0, ret_value=H5B_ITER_CONT; i<nsyms && H5B_ITER_CONT==ret_value; i++) {
         if (bt_udata->skip>0) {
             --bt_udata->skip;
         } else {
-            name = H5HL_peek (f, bt_udata->group->ent.cache.stab.heap_addr,
-                     name_off[i]);
+            name = H5HL_peek (f, bt_udata->group->ent.cache.stab.heap_addr, name_off[i]);
             assert (name);
             n = HDstrlen (name);
             if (n+1>sizeof(buf)) {
@@ -1149,7 +1158,7 @@ H5G_node_sumup(H5F_t *f, void UNUSED *_lt_key, haddr_t addr,
     assert(num_objs);
 
     /* Find the object node and add the number of symbol entries. */
-    if (NULL == (sn = H5AC_find(f, H5AC_SNODE, addr, NULL, NULL)))
+    if (NULL == (sn = H5AC_find_f(f, H5AC_SNODE, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, H5B_ITER_ERROR, "unable to load symbol table node");
     *num_objs += sn->nsyms;
     
@@ -1195,14 +1204,14 @@ H5G_node_name(H5F_t *f, void UNUSED *_lt_key, haddr_t addr,
     assert(bt_udata);
 
 
-    if (NULL == (sn = H5AC_find(f, H5AC_SNODE, addr, NULL, NULL)))
+    if (NULL == (sn = H5AC_find_f(f, H5AC_SNODE, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, H5B_ITER_ERROR, "unable to load symbol table node");
     
     /* Find the node, locate the object symbol table entry and retrieve the name */ 
     if(bt_udata->idx >= bt_udata->num_objs && bt_udata->idx < (bt_udata->num_objs+sn->nsyms)) {
             loc_idx = bt_udata->idx - bt_udata->num_objs; 
             name_off = sn->entry[loc_idx].name_off;  
-            name = (const char*)H5HL_peek (f, bt_udata->group->ent.cache.stab.heap_addr, name_off);
+            name = H5HL_peek (f, bt_udata->group->ent.cache.stab.heap_addr, name_off);
             assert (name);
             bt_udata->name = H5MM_strdup (name);
             HGOTO_DONE(H5B_ITER_STOP);
@@ -1247,7 +1256,7 @@ H5G_node_type(H5F_t *f, void UNUSED *_lt_key, haddr_t addr,
     assert(bt_udata);
 
     /* Find the node, locate the object symbol table entry and retrieve the type */ 
-    if (NULL == (sn = H5AC_find(f, H5AC_SNODE, addr, NULL, NULL)))
+    if (NULL == (sn = H5AC_find_f(f, H5AC_SNODE, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_SYM, H5E_CANTLOAD, H5B_ITER_ERROR, "unable to load symbol table node");
 
     if(bt_udata->idx >= bt_udata->num_objs && bt_udata->idx < (bt_udata->num_objs+sn->nsyms)) {
@@ -1318,7 +1327,7 @@ H5G_node_debug(H5F_t *f, haddr_t addr, FILE * stream, int indent,
 	    "Size of Node (in bytes):", (unsigned)H5G_node_size(f));
     fprintf(stream, "%*s%-*s %d of %d\n", indent, "", fwidth,
 	    "Number of Symbols:",
-	    sn->nsyms, 2 * H5G_node_k(f));
+	    sn->nsyms, 2 * H5F_SYM_LEAF_K(f));
 
     indent += 3;
     fwidth = MAX(0, fwidth - 3);
@@ -1339,46 +1348,3 @@ done:
     FUNC_LEAVE(ret_value);
 }
 
-
-/*-------------------------------------------------------------------------
- * Function:	H5G_node_k
- *
- * Purpose:	Replaced a macro to retrieve the symbol table leaf size,
- *              now that the generic properties are being used to store
- *              the values.
- *
- * Return:	Success:	Non-negative, and the symbol table leaf size is
- *                              returned.
- *
- * 		Failure:	Negative (should not happen)
- *
- * Programmer:	Raymond Lu
- *		slu@ncsa.uiuc.edu
- *		Oct 14 2001
- *
- * Modifications:
- *		Quincey Koziol, 2001-10-15
- *		Added this header and removed unused ret_value variable.
- *-------------------------------------------------------------------------
- */
-unsigned H5G_node_k(const H5F_t *f)
-{
-    unsigned sym_leaf_k;
-    H5P_genplist_t *plist;      /* Property list pointer */
-    unsigned ret_value;         /* Return value */
-
-    FUNC_ENTER_NOAPI(H5G_node_k, UFAIL);
-
-    assert(f);
-
-    if(NULL == (plist = H5I_object(f->shared->fcpl_id)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, UFAIL, "not a file access property list");
-    if(H5P_get(plist, H5F_CRT_SYM_LEAF_NAME, &sym_leaf_k) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, UFAIL, "can't get rank for symbol table leaf node"); 
-    
-    /* Set return value */
-    ret_value=sym_leaf_k;
-
-done:
-    FUNC_LEAVE(ret_value);
-}
diff --git a/src/H5Gpkg.h b/src/H5Gpkg.h
index 3fc8bd3..b058ea3 100644
--- a/src/H5Gpkg.h
+++ b/src/H5Gpkg.h
@@ -151,7 +151,6 @@ H5_DLL herr_t H5G_ent_encode_vec(H5F_t *f, uint8_t **pp,
 				  const H5G_entry_t *ent, int n);
 
 /* Functions that understand symbol table nodes */
-H5_DLL unsigned H5G_node_k(const H5F_t *f);
 H5_DLL H5B_iterate_t H5G_node_iterate (H5F_t *f, void UNUSED *_lt_key, haddr_t addr,
 		     void UNUSED *_rt_key, void *_udata);
 H5_DLL H5B_iterate_t H5G_node_sumup(H5F_t *f, void UNUSED *_lt_key, haddr_t addr,
diff --git a/src/H5Gprivate.h b/src/H5Gprivate.h
index 8515b2d..be360cb 100644
--- a/src/H5Gprivate.h
+++ b/src/H5Gprivate.h
@@ -26,6 +26,7 @@
 #include "H5private.h"
 #include "H5Bprivate.h"
 #include "H5Fprivate.h"
+#include "H5RSprivate.h"        /* Reference-counted strings            */
 
 /*
  * Define this to enable debugging.
@@ -95,8 +96,13 @@ typedef struct H5G_entry_t {
     H5G_type_t  type;                   /*type of information cached         */
     H5G_cache_t cache;                  /*cached data from object header     */
     H5F_t       *file;                  /*file to which this obj hdr belongs */
+#ifdef OLD_WAY
     char        *user_path;             /* Path to object, as opened by user */
     char        *canon_path;            /* Path to object, as found in file  */
+#else /* OLD_WAY */
+    H5RS_str_t  *user_path_r;           /* Path to object, as opened by user */
+    H5RS_str_t  *canon_path_r;          /* Path to object, as found in file  */
+#endif /* OLD_WAY */
     unsigned    user_path_hidden;       /* Whether the user's path is valid  */
 } H5G_entry_t;
 
@@ -123,6 +129,7 @@ typedef enum {
 
 /* Depth of group entry copy */
 typedef enum {
+    H5G_COPY_NULL,      /* Null destination names */
     H5G_COPY_LIMITED,   /* Limited copy from source to destination, omitting name & old name fields */
     H5G_COPY_SHALLOW,   /* Copy from source to destination, including name & old name fields */
     H5G_COPY_DEEP       /* Deep copy from source to destination, including duplicating name & old name fields */
@@ -174,8 +181,8 @@ H5_DLL herr_t H5G_ent_encode(H5F_t *f, uint8_t **pp, const H5G_entry_t *ent);
 H5_DLL herr_t H5G_ent_decode(H5F_t *f, const uint8_t **pp,
 			      H5G_entry_t *ent/*out*/);
 H5_DLL  herr_t H5G_replace_name(int type, H5G_entry_t *loc,
-        const char *src_name, H5G_entry_t *src_loc,
-        const char *dst_name, H5G_entry_t *dst_loc, H5G_names_op_t op);
+        H5RS_str_t *src_name, H5G_entry_t *src_loc,
+        H5RS_str_t *dst_name, H5G_entry_t *dst_loc, H5G_names_op_t op);
 H5_DLL  herr_t H5G_ent_copy(H5G_entry_t *dst, const H5G_entry_t *src,
             H5G_ent_copy_depth_t depth);
 H5_DLL  herr_t H5G_free_grp_name(H5G_t *grp);
diff --git a/src/H5Gstab.c b/src/H5Gstab.c
index 12d0ccb..e5e2535 100644
--- a/src/H5Gstab.c
+++ b/src/H5Gstab.c
@@ -12,6 +12,7 @@
 #include "H5private.h"
 #include "H5Eprivate.h"
 #include "H5Fpkg.h"         /*file access                             */
+#include "H5FLprivate.h"	/*Free Lists	  */
 #include "H5Gpkg.h"
 #include "H5HLprivate.h"
 #include "H5MMprivate.h"
@@ -21,6 +22,9 @@
 static int		interface_initialize_g = 0;
 #define INTERFACE_INIT	NULL
 
+/* Declare extern the PQ free list for the wrapped strings */
+H5FL_BLK_EXTERN(str_buf);
+
 /* Private prototypes */
 static herr_t H5G_insert_name(H5G_entry_t *loc, H5G_entry_t *obj,
         const char *name);
@@ -95,7 +99,7 @@ H5G_stab_create(H5F_t *f, size_t init, H5G_entry_t *self/*out*/)
      * Insert the symbol table message into the object header and the symbol
      * table entry.
      */
-    if (H5O_modify(self, H5O_STAB, H5O_NEW_MESG, H5O_FLAG_CONSTANT, &stab)<0) {
+    if (H5O_modify(self, H5O_STAB, H5O_NEW_MESG, H5O_FLAG_CONSTANT, 1, &stab)<0) {
 	H5O_close(self);
 	HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, FAIL, "can't create message");
     }
@@ -160,8 +164,8 @@ H5G_stab_find(H5G_entry_t *grp_ent, const char *name,
     /* change OBJ_ENT only if found */
     else {
         if (obj_ent) {
-            /* do a deep copy */
-            if (H5G_ent_copy(obj_ent, &(udata.ent),H5G_COPY_DEEP)<0)
+            /* do a NULL copy, since the obj_ent name will be constructed in H5G_insert_name() */
+            if (H5G_ent_copy(obj_ent, &(udata.ent),H5G_COPY_NULL)<0)
                 HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, FAIL, "unable to copy entry");
 
             /* insert the name into the symbol entry OBJ_ENT */
@@ -224,7 +228,7 @@ H5G_stab_insert(H5G_entry_t *grp_ent, const char *name, H5G_entry_t *obj_ent)
     udata.operation = H5G_OPER_INSERT;
     udata.name = name;
     udata.heap_addr = stab.heap_addr;
-    H5G_ent_copy(&(udata.ent),obj_ent,H5G_COPY_SHALLOW); /* Shallow copy here, deep copy happens in H5G_node_insert() callback() */
+    H5G_ent_copy(&(udata.ent),obj_ent,H5G_COPY_NULL); /* NULL copy here, no copies happens in H5G_node_insert() callback() */
 
     /* insert */
     if (H5B_insert(grp_ent->file, H5B_SNODE, stab.btree_addr, split_ratios, &udata) < 0)
@@ -301,6 +305,8 @@ done:
 static herr_t 
 H5G_insert_name(H5G_entry_t *loc, H5G_entry_t *obj, const char *name)
 {
+    char *new_user_path;        /* Pointer to new user path */
+    char *new_canon_path;       /* Pointer to new canonical path */
     size_t  name_len;           /* Length of name to append */
     size_t  user_path_len;      /* Length of location's user path name */
     size_t  canon_path_len;     /* Length of location's canonical path name */
@@ -313,55 +319,79 @@ H5G_insert_name(H5G_entry_t *loc, H5G_entry_t *obj, const char *name)
     assert(name);
  
     /* Only attempt to build a new name if the location's name exists */
-    if(loc->canon_path) {
+    if(loc->canon_path_r) {
+        const char *loc_user_path;      /* Pointer to raw string for user path */
+        const char *loc_canon_path;     /* Pointer to raw string for canonical path */
 
         /* Reset the object's previous names, if they exist */
-        H5MM_xfree(obj->user_path);
-        H5MM_xfree(obj->canon_path);
+        if(obj->user_path_r) {
+            H5RS_decr(obj->user_path_r);
+            obj->user_path_r=NULL;
+        } /* end if */
+        if(obj->canon_path_r) {
+            H5RS_decr(obj->canon_path_r);
+            obj->canon_path_r=NULL;
+        } /* end if */
         obj->user_path_hidden=0;
 
         /* Get the length of the strings involved */
-        user_path_len = HDstrlen(loc->user_path);
-        canon_path_len = HDstrlen(loc->canon_path);
+        user_path_len = H5RS_len(loc->user_path_r);
+        canon_path_len = H5RS_len(loc->canon_path_r);
         name_len = HDstrlen(name);
 
         /* Modify the object's user path */
 
+        /* Get the raw string for the user path */
+        loc_user_path=H5RS_GET_STR(loc->user_path_r);
+        assert(loc_user_path);
+
         /* The location's user path already ends in a '/' separator */
-        if ('/'==loc->user_path[user_path_len-1]) {
-            if (NULL==(obj->user_path = H5MM_malloc (user_path_len+name_len+1)))
+        if ('/'==loc_user_path[user_path_len-1]) {
+            if (NULL==(new_user_path = H5FL_BLK_MALLOC(str_buf,user_path_len+name_len+1)))
                 HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
-            HDstrcpy(obj->user_path, loc->user_path);
+            HDstrcpy(new_user_path, loc_user_path);
         } /* end if */
         /* The location's user path needs a separator */
         else {
-            if (NULL==(obj->user_path = H5MM_malloc (user_path_len+1+name_len+1)))
+            if (NULL==(new_user_path = H5FL_BLK_MALLOC(str_buf,user_path_len+1+name_len+1)))
                 HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
-            HDstrcpy(obj->user_path, loc->user_path);
-            HDstrcat(obj->user_path, "/");
+            HDstrcpy(new_user_path, loc_user_path);
+            HDstrcat(new_user_path, "/");
         } /* end else */
 
         /* Append the component's name */
-        HDstrcat(obj->user_path, name);
+        HDstrcat(new_user_path, name);
+
+        /* Give ownership of the user path to the entry */
+        obj->user_path_r=H5RS_own(new_user_path);
+        assert(obj->user_path_r);
 
         /* Modify the object's canonical path */
 
+        /* Get the raw string for the canonical path */
+        loc_canon_path=H5RS_GET_STR(loc->canon_path_r);
+        assert(loc_canon_path);
+
         /* The location's canonical path already ends in a '/' separator */
-        if ('/'==loc->canon_path[canon_path_len-1]) {
-            if (NULL==(obj->canon_path = H5MM_malloc (canon_path_len+name_len+1)))
+        if ('/'==loc_canon_path[canon_path_len-1]) {
+            if (NULL==(new_canon_path = H5FL_BLK_MALLOC(str_buf,canon_path_len+name_len+1)))
                 HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
-            HDstrcpy(obj->canon_path, loc->canon_path);
+            HDstrcpy(new_canon_path, loc_canon_path);
         } /* end if */
         /* The location's canonical path needs a separator */
         else {
-            if (NULL==(obj->canon_path = H5MM_malloc (canon_path_len+1+name_len+1)))
+            if (NULL==(new_canon_path = H5FL_BLK_MALLOC(str_buf,canon_path_len+1+name_len+1)))
                 HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
-            HDstrcpy(obj->canon_path, loc->canon_path);
-            HDstrcat(obj->canon_path, "/");
+            HDstrcpy(new_canon_path, loc_canon_path);
+            HDstrcat(new_canon_path, "/");
         } /* end else */
 
         /* Append the component's name */
-        HDstrcat(obj->canon_path, name);
+        HDstrcat(new_canon_path, name);
+
+        /* Give ownership of the canonical path to the entry */
+        obj->canon_path_r=H5RS_own(new_canon_path);
+        assert(obj->canon_path_r);
     } /* end if */
 
 done:
diff --git a/src/H5HG.c b/src/H5HG.c
index bc4a6de..27a5f6d 100644
--- a/src/H5HG.c
+++ b/src/H5HG.c
@@ -127,19 +127,19 @@ H5HG_create (H5F_t *f, size_t size)
 	HGOTO_ERROR (H5E_HEAP, H5E_CANTINIT, NULL,
 		     "unable to allocate file space for global heap");
     }
-    if (NULL==(heap = H5FL_ALLOC (H5HG_heap_t,1))) {
+    if (NULL==(heap = H5FL_CALLOC (H5HG_heap_t))) {
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL,
 		     "memory allocation failed");
     }
     heap->addr = addr;
     heap->size = size;
     heap->dirty = TRUE;
-    if (NULL==(heap->chunk = H5FL_BLK_ALLOC (heap_chunk,size,0))) {
+    if (NULL==(heap->chunk = H5FL_BLK_MALLOC (heap_chunk,size))) {
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL,
 		     "memory allocation failed");
     }
     heap->nalloc = H5HG_NOBJS (f, size);
-    if (NULL==(heap->obj = H5FL_ARR_ALLOC (H5HG_obj_t,heap->nalloc,1))) {
+    if (NULL==(heap->obj = H5FL_ARR_CALLOC (H5HG_obj_t,heap->nalloc))) {
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL,
 		     "memory allocation failed");
     }
@@ -246,12 +246,12 @@ H5HG_load (H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED udata1,
     assert (!udata2);
 
     /* Read the initial 4k page */
-    if (NULL==(heap = H5FL_ALLOC (H5HG_heap_t,1))) {
+    if (NULL==(heap = H5FL_CALLOC (H5HG_heap_t))) {
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL,
 		     "memory allocation failed");
     }
     heap->addr = addr;
-    if (NULL==(heap->chunk = H5FL_BLK_ALLOC (heap_chunk,H5HG_MINSIZE,0))) {
+    if (NULL==(heap->chunk = H5FL_BLK_MALLOC (heap_chunk,H5HG_MINSIZE))) {
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL,
 		     "memory allocation failed");
     }
@@ -301,7 +301,7 @@ H5HG_load (H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED udata1,
     /* Decode each object */
     p = heap->chunk + H5HG_SIZEOF_HDR (f);
     nalloc = H5HG_NOBJS (f, heap->size);
-    if (NULL==(heap->obj = H5FL_ARR_ALLOC (H5HG_obj_t,nalloc,1))) {
+    if (NULL==(heap->obj = H5FL_ARR_CALLOC (H5HG_obj_t,nalloc))) {
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL,
 		     "memory allocation failed");
     }
@@ -671,7 +671,7 @@ H5HG_peek (H5F_t *f, H5HG_t *hobj)
     assert (hobj);
 
     /* Load the heap and return a pointer to the object */
-    if (NULL==(heap=H5AC_find (f, H5AC_GHEAP, hobj->addr, NULL, NULL)))
+    if (NULL==(heap=H5AC_find_f (f, H5AC_GHEAP, hobj->addr, NULL, NULL)))
 	HGOTO_ERROR (H5E_HEAP, H5E_CANTLOAD, NULL, "unable to load heap");
     assert (hobj->idx>0 && hobj->idx<heap->nalloc);
     ret_value = heap->obj[hobj->idx].begin + H5HG_SIZEOF_OBJHDR (f);
@@ -679,7 +679,7 @@ H5HG_peek (H5F_t *f, H5HG_t *hobj)
 
     /*
      * Advance the heap in the CWFS list.  We might have done this already
-     * with the H5AC_find(), but it won't hurt to do it twice.
+     * with the H5AC_find_f(), but it won't hurt to do it twice.
      */
     if (heap->obj[0].begin) {
 	for (i=0; i<f->shared->ncwfs; i++) {
@@ -733,7 +733,7 @@ H5HG_read (H5F_t *f, H5HG_t *hobj, void *object/*out*/)
     assert (hobj);
 
     /* Load the heap */
-    if (NULL==(heap=H5AC_find (f, H5AC_GHEAP, hobj->addr, NULL, NULL)))
+    if (NULL==(heap=H5AC_find_f (f, H5AC_GHEAP, hobj->addr, NULL, NULL)))
 	HGOTO_ERROR (H5E_HEAP, H5E_CANTLOAD, NULL, "unable to load heap");
     assert (hobj->idx>0 && hobj->idx<heap->nalloc);
     assert (heap->obj[hobj->idx].begin);
@@ -745,7 +745,7 @@ H5HG_read (H5F_t *f, H5HG_t *hobj, void *object/*out*/)
 
     /*
      * Advance the heap in the CWFS list.  We might have done this already
-     * with the H5AC_find(), but it won't hurt to do it twice.
+     * with the H5AC_find_f(), but it won't hurt to do it twice.
      */
     if (heap->obj[0].begin) {
 	for (i=0; i<f->shared->ncwfs; i++) {
@@ -802,7 +802,7 @@ H5HG_link (H5F_t *f, H5HG_t *hobj, int adjust)
 	HGOTO_ERROR (H5E_HEAP, H5E_WRITEERROR, FAIL, "no write intent on file");
 
     /* Load the heap */
-    if (NULL==(heap=H5AC_find (f, H5AC_GHEAP, hobj->addr, NULL, NULL)))
+    if (NULL==(heap=H5AC_find_f (f, H5AC_GHEAP, hobj->addr, NULL, NULL)))
 	HGOTO_ERROR (H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load heap");
     assert (hobj->idx>0 && hobj->idx<heap->nalloc);
     assert (heap->obj[hobj->idx].begin);
@@ -855,7 +855,7 @@ H5HG_remove (H5F_t *f, H5HG_t *hobj)
         HGOTO_ERROR (H5E_HEAP, H5E_WRITEERROR, FAIL, "no write intent on file");
 
     /* Load the heap */
-    if (NULL==(heap=H5AC_find (f, H5AC_GHEAP, hobj->addr, NULL, NULL)))
+    if (NULL==(heap=H5AC_find_f (f, H5AC_GHEAP, hobj->addr, NULL, NULL)))
         HGOTO_ERROR (H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load heap");
     assert (hobj->idx>0 && hobj->idx<heap->nalloc);
     assert (heap->obj[hobj->idx].begin);
@@ -899,7 +899,7 @@ H5HG_remove (H5F_t *f, H5HG_t *hobj)
     } else {
         /*
          * If the heap is in the CWFS list then advance it one position.  The
-         * H5AC_find() might have done that too, but that's okay.  If the
+         * H5AC_find_f() might have done that too, but that's okay.  If the
          * heap isn't on the CWFS list then add it to the end.
          */
         for (i=0; i<f->shared->ncwfs; i++) {
@@ -959,7 +959,7 @@ H5HG_debug(H5F_t *f, haddr_t addr, FILE *stream, int indent,
     assert(indent >= 0);
     assert(fwidth >= 0);
 
-    if (NULL == (h = H5AC_find(f, H5AC_GHEAP, addr, NULL, NULL)))
+    if (NULL == (h = H5AC_find_f(f, H5AC_GHEAP, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load global heap collection");
     fprintf(stream, "%*sGlobal Heap Collection...\n", indent, "");
     fprintf(stream, "%*s%-*s %d\n", indent, "", fwidth,
diff --git a/src/H5HL.c b/src/H5HL.c
index d9e5d9c..e4b117c 100644
--- a/src/H5HL.c
+++ b/src/H5HL.c
@@ -111,6 +111,7 @@ H5HL_create(H5F_t *f, size_t size_hint, haddr_t *addr_p/*out*/)
 {
     H5HL_t	*heap = NULL;
     hsize_t	total_size;		/*total heap size on disk	*/
+    size_t      sizeof_hdr;             /* Cache H5HL header size for file */
     herr_t	ret_value = FAIL;
 
     FUNC_ENTER_NOAPI(H5HL_create, FAIL);
@@ -124,29 +125,32 @@ H5HL_create(H5F_t *f, size_t size_hint, haddr_t *addr_p/*out*/)
     }
     size_hint = H5HL_ALIGN(size_hint);
 
+    /* Cache this for later */
+    sizeof_hdr= H5HL_SIZEOF_HDR(f);
+
     /* allocate file version */
-    total_size = H5HL_SIZEOF_HDR(f) + size_hint;
+    total_size = sizeof_hdr + size_hint;
     if (HADDR_UNDEF==(*addr_p=H5MF_alloc(f, H5FD_MEM_LHEAP, total_size))) {
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL,
 		      "unable to allocate file memory");
     }
 
     /* allocate memory version */
-    if (NULL==(heap = H5FL_ALLOC(H5HL_t,1))) {
+    if (NULL==(heap = H5FL_CALLOC(H5HL_t))) {
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL,
 		     "memory allocation failed");
     }
-    heap->addr = *addr_p + (hsize_t)H5HL_SIZEOF_HDR(f);
+    heap->addr = *addr_p + (hsize_t)sizeof_hdr;
     heap->disk_alloc = size_hint;
     heap->mem_alloc = size_hint;
-    if (NULL==(heap->chunk = H5FL_BLK_ALLOC(heap_chunk,(H5HL_SIZEOF_HDR(f) + size_hint),1))) {
+    if (NULL==(heap->chunk = H5FL_BLK_CALLOC(heap_chunk,(sizeof_hdr + size_hint)))) {
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL,
 		     "memory allocation failed");
     }
 
     /* free list */
     if (size_hint) {
-	if (NULL==(heap->freelist = H5FL_ALLOC(H5HL_free_t,0))) {
+	if (NULL==(heap->freelist = H5FL_MALLOC(H5HL_free_t))) {
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL,
 			 "memory allocation failed");
 	}
@@ -206,6 +210,7 @@ H5HL_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED udata1,
 	  void * UNUSED udata2)
 {
     uint8_t		hdr[52];
+    size_t              sizeof_hdr;     /* Cache H5HL header size for file */
     const uint8_t	*p = NULL;
     H5HL_t		*heap = NULL;
     H5HL_free_t		*fl = NULL, *tail = NULL;
@@ -214,17 +219,20 @@ H5HL_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED udata1,
 
     FUNC_ENTER_NOAPI(H5HL_load, NULL);
 
+    /* Cache this for later */
+    sizeof_hdr= H5HL_SIZEOF_HDR(f);
+
     /* check arguments */
     assert(f);
     assert(H5F_addr_defined(addr));
-    assert(H5HL_SIZEOF_HDR(f) <= sizeof hdr);
+    assert(sizeof_hdr <= sizeof(hdr));
     assert(!udata1);
     assert(!udata2);
 
-    if (H5F_block_read(f, H5FD_MEM_LHEAP, addr, H5HL_SIZEOF_HDR(f), dxpl_id, hdr) < 0)
+    if (H5F_block_read(f, H5FD_MEM_LHEAP, addr, sizeof_hdr, dxpl_id, hdr) < 0)
 	HGOTO_ERROR(H5E_HEAP, H5E_READERROR, NULL, "unable to read heap header");
     p = hdr;
-    if (NULL==(heap = H5FL_ALLOC(H5HL_t,1)))
+    if (NULL==(heap = H5FL_CALLOC(H5HL_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     
     /* magic number */
@@ -246,19 +254,19 @@ H5HL_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED udata1,
 
     /* data */
     H5F_addr_decode(f, &p, &(heap->addr));
-    heap->chunk = H5FL_BLK_ALLOC(heap_chunk,(H5HL_SIZEOF_HDR(f) + heap->mem_alloc),1);
+    heap->chunk = H5FL_BLK_CALLOC(heap_chunk,(sizeof_hdr + heap->mem_alloc));
     if (NULL==heap->chunk)
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     if (heap->disk_alloc &&
             H5F_block_read(f, H5FD_MEM_LHEAP, heap->addr, heap->disk_alloc,
-            dxpl_id, heap->chunk + H5HL_SIZEOF_HDR(f)) < 0)
+            dxpl_id, heap->chunk + sizeof_hdr) < 0)
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "unable to read heap data");
 
     /* free list */
     while (H5HL_FREE_NULL != free_block) {
 	if (free_block >= heap->disk_alloc)
 	    HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "bad heap free list");
-	if (NULL==(fl = H5FL_ALLOC(H5HL_free_t,0)))
+	if (NULL==(fl = H5FL_MALLOC(H5HL_free_t)))
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 	fl->offset = free_block;
 	fl->prev = tail;
@@ -267,7 +275,7 @@ H5HL_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED udata1,
 	tail = fl;
 	if (!heap->freelist) heap->freelist = fl;
 
-	p = heap->chunk + H5HL_SIZEOF_HDR(f) + free_block;
+	p = heap->chunk + sizeof_hdr + free_block;
 	H5F_DECODE_LENGTH(f, p, free_block);
 	H5F_DECODE_LENGTH(f, p, fl->size);
 
@@ -323,6 +331,7 @@ H5HL_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HL_t *heap)
     uint8_t	*p = heap->chunk;
     H5HL_free_t	*fl = heap->freelist;
     haddr_t	hdr_end_addr;
+    size_t      sizeof_hdr;             /* Cache H5HL header size for file */
     herr_t      ret_value=SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5HL_flush, FAIL);
@@ -333,6 +342,9 @@ H5HL_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HL_t *heap)
     assert(heap);
 
     if (heap->dirty) {
+        /* Cache this for later */
+        sizeof_hdr= H5HL_SIZEOF_HDR(f);
+
 	/*
 	 * If the heap grew larger than disk storage then move the
 	 * data segment of the heap to a larger contiguous block of
@@ -367,7 +379,7 @@ H5HL_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HL_t *heap)
 	 */
 	while (fl) {
 	    assert (fl->offset == H5HL_ALIGN (fl->offset));
-	    p = heap->chunk + H5HL_SIZEOF_HDR(f) + fl->offset;
+	    p = heap->chunk + sizeof_hdr + fl->offset;
 	    if (fl->next) {
 		H5F_ENCODE_LENGTH(f, p, fl->next->offset);
 	    } else {
@@ -380,19 +392,19 @@ H5HL_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5HL_t *heap)
 	/*
 	 * Copy buffer to disk.
 	 */
-	hdr_end_addr = addr + (hsize_t)H5HL_SIZEOF_HDR(f);
+	hdr_end_addr = addr + (hsize_t)sizeof_hdr;
 	if (H5F_addr_eq(heap->addr, hdr_end_addr)) {
 	    /* The header and data are contiguous */
 	    if (H5F_block_write(f, H5FD_MEM_LHEAP, addr,
-				(H5HL_SIZEOF_HDR(f)+heap->disk_alloc),
+				(sizeof_hdr+heap->disk_alloc),
 				dxpl_id, heap->chunk) < 0)
 		HGOTO_ERROR(H5E_HEAP, H5E_WRITEERROR, FAIL, "unable to write heap header and data to file");
 	} else {
-	    if (H5F_block_write(f, H5FD_MEM_LHEAP, addr, H5HL_SIZEOF_HDR(f),
+	    if (H5F_block_write(f, H5FD_MEM_LHEAP, addr, sizeof_hdr,
 				dxpl_id, heap->chunk)<0)
 		HGOTO_ERROR(H5E_HEAP, H5E_WRITEERROR, FAIL, "unable to write heap header to file");
 	    if (H5F_block_write(f, H5FD_MEM_LHEAP, heap->addr, heap->disk_alloc,
-				dxpl_id, heap->chunk + H5HL_SIZEOF_HDR(f)) < 0)
+				dxpl_id, heap->chunk + sizeof_hdr) < 0)
 		HGOTO_ERROR(H5E_HEAP, H5E_WRITEERROR, FAIL, "unable to write heap data to file");
 	}
 
@@ -456,7 +468,7 @@ H5HL_read(H5F_t *f, haddr_t addr, size_t offset, size_t size, void *buf)
     assert(f);
     assert (H5F_addr_defined(addr));
 
-    if (NULL == (heap = H5AC_find(f, H5AC_LHEAP, addr, NULL, NULL)))
+    if (NULL == (heap = H5AC_find_f(f, H5AC_LHEAP, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "unable to load heap");
     assert(offset < heap->mem_alloc);
     assert(offset + size <= heap->mem_alloc);
@@ -507,8 +519,8 @@ done:
 const void *
 H5HL_peek(H5F_t *f, haddr_t addr, size_t offset)
 {
-    H5HL_t		*heap = NULL;
-    const void		*ret_value = NULL;
+    H5HL_t		*heap;
+    const void		*ret_value;
 
     FUNC_ENTER_NOAPI(H5HL_peek, NULL);
 
@@ -516,7 +528,7 @@ H5HL_peek(H5F_t *f, haddr_t addr, size_t offset)
     assert(f);
     assert(H5F_addr_defined(addr));
 
-    if (NULL == (heap = H5AC_find(f, H5AC_LHEAP, addr, NULL, NULL)))
+    if (NULL == (heap = H5AC_find_f(f, H5AC_LHEAP, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, NULL, "unable to load heap");
     assert(offset < heap->mem_alloc);
 
@@ -584,6 +596,7 @@ H5HL_insert(H5F_t *f, haddr_t addr, size_t buf_size, const void *buf)
     size_t	offset = 0;
     size_t	need_size, old_size, need_more;
     hbool_t	found;
+    size_t      sizeof_hdr;     /* Cache H5HL header size for file */
     size_t	ret_value;      /* Return value */
 
     FUNC_ENTER_NOAPI(H5HL_insert, (size_t)(-1));
@@ -596,10 +609,13 @@ H5HL_insert(H5F_t *f, haddr_t addr, size_t buf_size, const void *buf)
     if (0==(f->intent & H5F_ACC_RDWR))
 	HGOTO_ERROR (H5E_HEAP, H5E_WRITEERROR, (size_t)(-1), "no write intent on file");
 
-    if (NULL == (heap = H5AC_find(f, H5AC_LHEAP, addr, NULL, NULL)))
+    if (NULL == (heap = H5AC_find_f(f, H5AC_LHEAP, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, (size_t)(-1), "unable to load heap");
     heap->dirty += 1;
 
+    /* Cache this for later */
+    sizeof_hdr= H5HL_SIZEOF_HDR(f);
+
     /*
      * In order to keep the free list descriptors aligned on word boundaries,
      * whatever that might mean, we round the size up to the next multiple of
@@ -669,7 +685,7 @@ H5HL_insert(H5F_t *f, haddr_t addr, size_t buf_size, const void *buf)
 	     */
 	    offset = heap->mem_alloc;
 	    if (need_more - need_size >= H5HL_SIZEOF_FREE(f)) {
-		if (NULL==(fl = H5FL_ALLOC(H5HL_free_t,0)))
+		if (NULL==(fl = H5FL_MALLOC(H5HL_free_t)))
 		    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, (size_t)(-1), "memory allocation failed");
 		fl->offset = heap->mem_alloc + need_size;
 		fl->size = need_more - need_size;
@@ -699,17 +715,17 @@ H5HL_insert(H5F_t *f, haddr_t addr, size_t buf_size, const void *buf)
 	old_size = heap->mem_alloc;
 	heap->mem_alloc += need_more;
 	heap->chunk = H5FL_BLK_REALLOC(heap_chunk,heap->chunk,
-				   (H5HL_SIZEOF_HDR(f) + heap->mem_alloc));
+				   (sizeof_hdr + heap->mem_alloc));
 	if (NULL==heap->chunk)
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, (size_t)(-1), "memory allocation failed");
 	
 	/* clear new section so junk doesn't appear in the file */
-	HDmemset(heap->chunk + H5HL_SIZEOF_HDR(f) + old_size, 0, need_more);
+	HDmemset(heap->chunk + sizeof_hdr + old_size, 0, need_more);
     }
     /*
      * Copy the data into the heap
      */
-    HDmemcpy(heap->chunk + H5HL_SIZEOF_HDR(f) + offset, buf, buf_size);
+    HDmemcpy(heap->chunk + sizeof_hdr + offset, buf, buf_size);
 
     /* Set return value */
     ret_value=offset;
@@ -757,7 +773,7 @@ H5HL_write(H5F_t *f, haddr_t addr, size_t offset, size_t size, const void *buf)
     if (0==(f->intent & H5F_ACC_RDWR))
 	HGOTO_ERROR (H5E_HEAP, H5E_WRITEERROR, FAIL, "no write intent on file");
 
-    if (NULL == (heap = H5AC_find(f, H5AC_LHEAP, addr, NULL, NULL)))
+    if (NULL == (heap = H5AC_find_f(f, H5AC_LHEAP, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load heap");
     assert(offset < heap->mem_alloc);
     assert(offset + size <= heap->mem_alloc);
@@ -815,7 +831,7 @@ H5HL_remove(H5F_t *f, haddr_t addr, size_t offset, size_t size)
 	HGOTO_ERROR (H5E_HEAP, H5E_WRITEERROR, FAIL, "no write intent on file");
 
     size = H5HL_ALIGN (size);
-    if (NULL == (heap = H5AC_find(f, H5AC_LHEAP, addr, NULL, NULL)))
+    if (NULL == (heap = H5AC_find_f(f, H5AC_LHEAP, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load heap");
     assert(offset < heap->mem_alloc);
     assert(offset + size <= heap->mem_alloc);
@@ -883,7 +899,7 @@ H5HL_remove(H5F_t *f, haddr_t addr, size_t offset, size_t size)
     /*
      * Add an entry to the free list.
      */
-    if (NULL==(fl = H5FL_ALLOC(H5HL_free_t,0)))
+    if (NULL==(fl = H5FL_MALLOC(H5HL_free_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     fl->offset = offset;
     fl->size = size;
@@ -936,7 +952,7 @@ H5HL_debug(H5F_t *f, haddr_t addr, FILE * stream, int indent, int fwidth)
     assert(indent >= 0);
     assert(fwidth >= 0);
 
-    if (NULL == (h = H5AC_find(f, H5AC_LHEAP, addr, NULL, NULL)))
+    if (NULL == (h = H5AC_find_f(f, H5AC_LHEAP, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_HEAP, H5E_CANTLOAD, FAIL, "unable to load heap");
     fprintf(stream, "%*sLocal Heap...\n", indent, "");
     fprintf(stream, "%*s%-*s %d\n", indent, "", fwidth,
diff --git a/src/H5I.c b/src/H5I.c
index b2a0eac..fa92bf9 100644
--- a/src/H5I.c
+++ b/src/H5I.c
@@ -359,8 +359,10 @@ H5I_clear_group(H5I_type_t grp, hbool_t force)
              * Do nothing to the object if the reference count is larger than
              * one and forcing is off.
              */
-            if (!force && cur->count>1)
+            if (!force && cur->count>1) {
+                next=cur->next;
                 continue;
+            } /* end if */
 
             /* Check for a 'free' function and call it, if it exists */
             if (grp_ptr->free_func && (grp_ptr->free_func)(cur->obj_ptr)<0) {
@@ -540,7 +542,7 @@ H5I_register(H5I_type_t grp, void *object)
     grp_ptr = H5I_id_group_list_g[grp];
     if (grp_ptr == NULL || grp_ptr->count <= 0)
 	HGOTO_ERROR(H5E_ATOM, H5E_BADGROUP, FAIL, "invalid group");
-    if ((id_ptr = H5FL_ALLOC(H5I_id_info_t,0)) == NULL)
+    if ((id_ptr = H5FL_MALLOC(H5I_id_info_t)) == NULL)
         HGOTO_ERROR(H5E_ATOM, H5E_NOSPACE, FAIL, "memory allocation failed");
 
     /* Create the struct & it's ID */
@@ -1156,11 +1158,11 @@ H5Iget_name(hid_t id, char *name/*out*/, size_t size)
 
     /* get symbol table entry */
     if(NULL!=(ent = H5G_loc(id))) {
-        if (ent->user_path != NULL && ent->user_path_hidden==0) {
-            len = HDstrlen(ent->user_path);
+        if (ent->user_path_r != NULL && ent->user_path_hidden==0) {
+            len = H5RS_len(ent->user_path_r);
 
             if(name) {
-                HDstrncpy(name, ent->user_path, MIN(len+1,size));
+                HDstrncpy(name, H5RS_GET_STR(ent->user_path_r), MIN(len+1,size));
                 if(len >= size)
                     name[size-1]='\0';
             } /* end if */
diff --git a/src/H5MMprivate.h b/src/H5MMprivate.h
index 1dac78e..5e98b0e 100644
--- a/src/H5MMprivate.h
+++ b/src/H5MMprivate.h
@@ -15,7 +15,7 @@
  *-------------------------------------------------------------------------
  */
 #ifndef _H5MMprivate_H
-#define _H5MMprivate_h
+#define _H5MMprivate_H
 
 #include "H5MMpublic.h"
 
@@ -29,7 +29,7 @@
 #define H5MM_malloc(Z)	HDmalloc(MAX(1,Z))
 #define H5MM_calloc(Z)	HDcalloc(1,MAX(1,Z))
 #endif /* H5_MALLOC_WORKS */
-#define H5MM_free(Z)	HDfree(1,Z)
+#define H5MM_free(Z)	HDfree(Z)
 
 /*
  * Library prototypes...
diff --git a/src/H5O.c b/src/H5O.c
index 7817b55..e266b86 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -27,6 +27,10 @@
 #include "H5Oprivate.h"
 #include "H5Pprivate.h"
 
+#ifdef H5_HAVE_GETTIMEOFDAY
+#include <sys/time.h>
+#endif /* H5_HAVE_GETTIMEOFDAY */
+
 #define PABLO_MASK	H5O_mask
 
 /* PRIVATE PROTOTYPES */
@@ -39,7 +43,6 @@ static unsigned H5O_alloc(H5F_t *f, H5O_t *oh, const H5O_class_t *type,
 		      size_t size);
 static unsigned H5O_alloc_extend_chunk(H5O_t *oh, unsigned chunkno, size_t size);
 static unsigned H5O_alloc_new_chunk(H5F_t *f, H5O_t *oh, size_t size);
-static herr_t H5O_touch_oh(H5F_t *f, H5O_t *oh, hbool_t force);
 
 /* H5O inherits cache-like properties from H5AC */
 static const H5AC_class_t H5AC_OHDR[1] = {{
@@ -73,6 +76,7 @@ static const H5O_class_t *const message_type_g[] = {
     NULL,		/*0x000F Shared header message			*/
     H5O_CONT,		/*0x0010 Object header continuation		*/
     H5O_STAB,		/*0x0011 Symbol table				*/
+    H5O_MTIME_NEW,	/*0x0012 New Object modification date and time  */
 };
 
 /*
@@ -168,7 +172,6 @@ H5O_create(H5F_t *f, size_t size_hint, H5G_entry_t *ent/*out*/)
     assert(f);
     assert(ent);
 
-    HDmemset(ent, 0, sizeof(H5G_entry_t));
     size_hint = H5O_ALIGN (MAX (H5O_MIN_SIZE, size_hint));
 
     /* allocate disk space for header and first chunk */
@@ -224,7 +227,7 @@ H5O_init(H5F_t *f, size_t size_hint, H5G_entry_t *ent/*out*/, haddr_t header)
     ent->header = header;
 
     /* allocate the object header and fill in header fields */
-    if (NULL == (oh = H5FL_ALLOC(H5O_t, 1)))
+    if (NULL == (oh = H5FL_MALLOC(H5O_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
     oh->dirty = TRUE;
@@ -235,7 +238,7 @@ H5O_init(H5F_t *f, size_t size_hint, H5G_entry_t *ent/*out*/, haddr_t header)
     oh->nchunks = 1;
     oh->alloc_nchunks = H5O_NCHUNKS;
 
-    if (NULL == (oh->chunk = H5FL_ARR_ALLOC(H5O_chunk_t, oh->alloc_nchunks, 0)))
+    if (NULL == (oh->chunk = H5FL_ARR_MALLOC(H5O_chunk_t, oh->alloc_nchunks)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
     tmp_addr = ent->header + (hsize_t)H5O_SIZEOF_HDR(f);
@@ -243,14 +246,14 @@ H5O_init(H5F_t *f, size_t size_hint, H5G_entry_t *ent/*out*/, haddr_t header)
     oh->chunk[0].addr = tmp_addr;
     oh->chunk[0].size = size_hint;
 
-    if (NULL == (oh->chunk[0].image = H5FL_BLK_ALLOC(chunk_image, size_hint, 1)))
+    if (NULL == (oh->chunk[0].image = H5FL_BLK_CALLOC(chunk_image, size_hint)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     
     /* create the message list and initialize the first message */
     oh->nmesgs = 1;
     oh->alloc_nmesgs = H5O_NMESGS;
 
-    if (NULL == (oh->mesg = H5FL_ARR_ALLOC(H5O_mesg_t, oh->alloc_nmesgs, 1)))
+    if (NULL == (oh->mesg = H5FL_ARR_CALLOC(H5O_mesg_t, oh->alloc_nmesgs)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
     oh->mesg[0].type = H5O_NULL;
@@ -431,7 +434,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED _udata1,
     assert(!_udata2);
 
     /* allocate ohdr and init chunk list */
-    if (NULL==(oh = H5FL_ALLOC(H5O_t,1)))
+    if (NULL==(oh = H5FL_CALLOC(H5O_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* read fixed-lenth part of object header */
@@ -461,7 +464,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED _udata1,
 
     /* build the message array */
     oh->alloc_nmesgs = MAX(H5O_NMESGS, nmesgs);
-    if (NULL==(oh->mesg=H5FL_ARR_ALLOC(H5O_mesg_t,oh->alloc_nmesgs,1)))
+    if (NULL==(oh->mesg=H5FL_ARR_CALLOC(H5O_mesg_t,oh->alloc_nmesgs)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* read each chunk from disk */
@@ -483,7 +486,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void * UNUSED _udata1,
 	oh->chunk[chunkno].dirty = FALSE;
 	oh->chunk[chunkno].addr = chunk_addr;
 	oh->chunk[chunkno].size = chunk_size;
-	if (NULL==(oh->chunk[chunkno].image = H5FL_BLK_ALLOC(chunk_image,chunk_size,0)))
+	if (NULL==(oh->chunk[chunkno].image = H5FL_BLK_MALLOC(chunk_image,chunk_size)))
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 	if (H5F_block_read(f, H5FD_MEM_OHDR, chunk_addr, chunk_size, dxpl_id,
 			   oh->chunk[chunkno].image) < 0)
@@ -595,6 +598,7 @@ H5O_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5O_t *oh)
     uint8_t	buf[16], *p;
     int	id;
     unsigned	u;
+    H5O_mesg_t *curr_msg;       /* Pointer to current message being operated on */
     H5O_cont_t	*cont = NULL;
     herr_t	(*encode)(H5F_t*, uint8_t*, const void*) = NULL;
     unsigned combine=0;        /* Whether to combine the object header prefix & the first chunk */
@@ -642,26 +646,26 @@ H5O_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5O_t *oh)
         } /* end else */
             
 	/* encode messages */
-	for (u = 0; u < oh->nmesgs; u++) {
-	    if (oh->mesg[u].dirty) {
-                p = oh->mesg[u].raw - H5O_SIZEOF_MSGHDR(f);
+	for (u = 0, curr_msg=&oh->mesg[0]; u < oh->nmesgs; u++,curr_msg++) {
+	    if (curr_msg->dirty) {
+                p = curr_msg->raw - H5O_SIZEOF_MSGHDR(f);
 
-                id = oh->mesg[u].type->id;
+                id = curr_msg->type->id;
                 UINT16ENCODE(p, id);
-                assert (oh->mesg[u].raw_size<H5O_MAX_SIZE);
-                UINT16ENCODE(p, oh->mesg[u].raw_size);
-                *p++ = oh->mesg[u].flags;
+                assert (curr_msg->raw_size<H5O_MAX_SIZE);
+                UINT16ENCODE(p, curr_msg->raw_size);
+                *p++ = curr_msg->flags;
                 *p++ = 0; /*reserved*/
                 *p++ = 0; /*reserved*/
                 *p++ = 0; /*reserved*/
                 
-                if (oh->mesg[u].native) {
-                    assert(oh->mesg[u].type->encode);
+                if (curr_msg->native) {
+                    assert(curr_msg->type->encode);
 
                     /* allocate file space for chunks that have none yet */
-                    if (H5O_CONT_ID == oh->mesg[u].type->id &&
-                            !H5F_addr_defined(((H5O_cont_t *)(oh->mesg[u].native))->addr)) {
-                        cont = (H5O_cont_t *) (oh->mesg[u].native);
+                    if (H5O_CONT_ID == curr_msg->type->id &&
+                            !H5F_addr_defined(((H5O_cont_t *)(curr_msg->native))->addr)) {
+                        cont = (H5O_cont_t *) (curr_msg->native);
                         assert(cont->chunkno < oh->nchunks);
                         assert(!H5F_addr_defined(oh->chunk[cont->chunkno].addr));
                         cont->size = oh->chunk[cont->chunkno].size;
@@ -676,23 +680,23 @@ H5O_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5O_t *oh)
                      * encode a Shared Object message instead of the object
                      * which is being shared.
                      */
-                    assert(oh->mesg[u].raw >=
-                       oh->chunk[oh->mesg[u].chunkno].image);
-                    assert (oh->mesg[u].raw_size ==
-                        H5O_ALIGN (oh->mesg[u].raw_size));
-                    assert(oh->mesg[u].raw + oh->mesg[u].raw_size <=
-                       oh->chunk[oh->mesg[u].chunkno].image +
-                       oh->chunk[oh->mesg[u].chunkno].size);
-                    if (oh->mesg[u].flags & H5O_FLAG_SHARED) {
+                    assert(curr_msg->raw >=
+                       oh->chunk[curr_msg->chunkno].image);
+                    assert (curr_msg->raw_size ==
+                        H5O_ALIGN (curr_msg->raw_size));
+                    assert(curr_msg->raw + curr_msg->raw_size <=
+                       oh->chunk[curr_msg->chunkno].image +
+                       oh->chunk[curr_msg->chunkno].size);
+                    if (curr_msg->flags & H5O_FLAG_SHARED) {
                         encode = H5O_SHARED->encode;
                     } else {
-                        encode = oh->mesg[u].type->encode;
+                        encode = curr_msg->type->encode;
                     }
-                    if ((encode)(f, oh->mesg[u].raw, oh->mesg[u].native)<0)
+                    if ((encode)(f, curr_msg->raw, curr_msg->native)<0)
                         HGOTO_ERROR(H5E_OHDR, H5E_CANTENCODE, FAIL, "unable to encode object header message");
                 }
-                oh->mesg[u].dirty = FALSE;
-                oh->chunk[oh->mesg[u].chunkno].dirty = TRUE;
+                curr_msg->dirty = FALSE;
+                oh->chunk[curr_msg->chunkno].dirty = TRUE;
 	    }
 	}
 
@@ -702,7 +706,7 @@ H5O_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5O_t *oh)
                 assert(H5F_addr_defined(oh->chunk[u].addr));
                 if(u==0 && combine) {
                     /* Allocate space for the combined prefix and first chunk */
-                    if((p=H5FL_BLK_ALLOC(chunk_image,(H5O_SIZEOF_HDR(f)+oh->chunk[u].size),0))==NULL)
+                    if((p=H5FL_BLK_MALLOC(chunk_image,(H5O_SIZEOF_HDR(f)+oh->chunk[u].size)))==NULL)
                         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
                     /* Copy in the prefix */
@@ -739,11 +743,11 @@ H5O_flush(H5F_t *f, hid_t dxpl_id, hbool_t destroy, haddr_t addr, H5O_t *oh)
 	oh->chunk = H5FL_ARR_FREE(H5O_chunk_t,oh->chunk);
 
 	/* destroy messages */
-	for (u = 0; u < oh->nmesgs; u++) {
-	    if (oh->mesg[u].flags & H5O_FLAG_SHARED) {
-                H5O_free(H5O_SHARED, oh->mesg[u].native);
+	for (u = 0, curr_msg=&oh->mesg[0]; u < oh->nmesgs; u++,curr_msg++) {
+	    if (curr_msg->flags & H5O_FLAG_SHARED) {
+                H5O_free(H5O_SHARED, curr_msg->native);
 	    } else {
-                H5O_free(oh->mesg[u].type, oh->mesg[u].native);
+                H5O_free(curr_msg->type, curr_msg->native);
 	    }
 	}
 	oh->mesg = H5FL_ARR_FREE(H5O_mesg_t,oh->mesg);
@@ -969,7 +973,7 @@ H5O_count (H5G_entry_t *ent, const H5O_class_t *type)
     assert (type);
 
     /* Load the object header */
-    if (NULL==(oh=H5AC_find (ent->file, H5AC_OHDR, ent->header, NULL, NULL)))
+    if (NULL==(oh=H5AC_find_f (ent->file, H5AC_OHDR, ent->header, NULL, NULL)))
 	HGOTO_ERROR (H5E_OHDR, H5E_CANTLOAD, FAIL, "unable to load object header");
 
     for (u=acc=0; u<oh->nmesgs; u++) {
@@ -1020,7 +1024,7 @@ H5O_exists(H5G_entry_t *ent, const H5O_class_t *type, int sequence)
     assert(sequence>=0);
 
     /* Load the object header */
-    if (NULL==(oh=H5AC_find(ent->file, H5AC_OHDR, ent->header, NULL, NULL)))
+    if (NULL==(oh=H5AC_find_f(ent->file, H5AC_OHDR, ent->header, NULL, NULL)))
 	HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, FAIL, "unable to load object header");
 
     /* Scan through the messages looking for the right one */
@@ -1182,7 +1186,7 @@ H5O_find_in_ohdr(H5F_t *f, haddr_t addr, const H5O_class_t **type_p,
     assert(type_p);
 
     /* Load the object header */
-    if (NULL == (oh = H5AC_find(f, H5AC_OHDR, addr, NULL, NULL)))
+    if (NULL == (oh = H5AC_find_f(f, H5AC_OHDR, addr, NULL, NULL)))
 	HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, UFAIL, "unable to load object header");
 
     /* Scan through the messages looking for the right one */
@@ -1244,6 +1248,10 @@ done:
  *		the sequence number 5 if there is no message with sequence
  *		number 4).
  *
+ *              The UPDATE_TIME argument is a boolean that allows the caller
+ *              to skip updating the modification time.  This is useful when
+ *              several calls to H5O_modify will be made in a sequence.
+ *
  * Return:	Success:	The sequence number of the message that
  *				was modified or created.
  *
@@ -1264,14 +1272,15 @@ done:
  */
 int
 H5O_modify(H5G_entry_t *ent, const H5O_class_t *type, int overwrite,
-	   unsigned flags, const void *mesg)
+   unsigned flags, unsigned update_time, const void *mesg)
 {
-    H5O_t		*oh = NULL;
+    H5O_t		*oh=NULL;
     int		        sequence;
-    unsigned		idx;
+    unsigned		idx;            /* Index of message to modify */
+    H5O_mesg_t         *idx_msg;        /* Pointer to message to modify */
     int		        ret_value = FAIL;
-    size_t		size = 0;
-    H5O_shared_t	sh_mesg = {0,{{0,0}}};
+    size_t		size=0;
+    H5O_shared_t	sh_mesg;
 
     FUNC_ENTER_NOAPI(H5O_modify, FAIL);
 
@@ -1290,8 +1299,8 @@ H5O_modify(H5G_entry_t *ent, const H5O_class_t *type, int overwrite,
 	HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, FAIL, "unable to load object header");
 
     /* Count similar messages */
-    for (idx = 0, sequence = -1; idx < oh->nmesgs; idx++) {
-	if (type->id != oh->mesg[idx].type->id)
+    for (idx = 0, sequence = -1, idx_msg=&oh->mesg[0]; idx < oh->nmesgs; idx++, idx_msg++) {
+	if (type->id != idx_msg->type->id)
             continue;
 	if (++sequence == overwrite)
             break;
@@ -1311,6 +1320,8 @@ H5O_modify(H5G_entry_t *ent, const H5O_class_t *type, int overwrite,
     if (overwrite < 0) {
 	/* Allocate space for the new message */
 	if (flags & H5O_FLAG_SHARED) {
+	    HDmemset(&sh_mesg,0,sizeof(H5O_shared_t));
+
 	    if (NULL==type->get_share)
 		HGOTO_ERROR (H5E_OHDR, H5E_UNSUPPORTED, FAIL, "message class is not sharable");
 	    if ((type->get_share)(ent->file, mesg, &sh_mesg/*out*/)<0) {
@@ -1342,7 +1353,8 @@ H5O_modify(H5G_entry_t *ent, const H5O_class_t *type, int overwrite,
 		size = (H5O_SHARED->raw_size)(ent->file, &sh_mesg);
 	    }
 	}
-	if (0==(flags & H5O_FLAG_SHARED)) {
+        /* This can't be an 'else' statement due to the possibility of the shared bit getting turned off above */
+	if (0== (flags & H5O_FLAG_SHARED)) {
 	    size = (type->raw_size) (ent->file, mesg);
 	    if (size>=H5O_MAX_SIZE)
 		HGOTO_ERROR (H5E_OHDR, H5E_CANTINIT, FAIL, "object header message is too large (16k max)");
@@ -1358,25 +1370,28 @@ H5O_modify(H5G_entry_t *ent, const H5O_class_t *type, int overwrite,
 	HGOTO_ERROR (H5E_OHDR, H5E_WRITEERROR, FAIL, "unable to modify shared (constant) message");
     }
     
+    /* Set pointer to the correct message */
+    idx_msg=&oh->mesg[idx];
 
     /* Copy the native value into the object header */
     if (flags & H5O_FLAG_SHARED) {
-        if (NULL==(oh->mesg[idx].native = H5MM_malloc (sizeof (H5O_shared_t))))
+        if (NULL==(idx_msg->native = H5MM_malloc (sizeof (H5O_shared_t))))
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
-        HDmemcpy(oh->mesg[idx].native,&sh_mesg,sizeof(H5O_shared_t));
+        HDmemcpy(idx_msg->native,&sh_mesg,sizeof(H5O_shared_t));
     } else {
-	if (oh->mesg[idx].native)
-	    H5O_reset (oh->mesg[idx].type, oh->mesg[idx].native);
-	oh->mesg[idx].native = (type->copy) (mesg, oh->mesg[idx].native);
-	if (NULL == oh->mesg[idx].native)
+	if (idx_msg->native)
+	    H5O_reset (idx_msg->type, idx_msg->native);
+	idx_msg->native = (type->copy) (mesg, idx_msg->native);
+	if (NULL == idx_msg->native)
 	    HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to copy message to object header");
     }
 
     /* Update the modification time message if any */
-    H5O_touch_oh(ent->file, oh, FALSE);
+    if(update_time)
+        H5O_touch_oh(ent->file, oh, FALSE);
     
-    oh->mesg[idx].flags = flags;
-    oh->mesg[idx].dirty = TRUE;
+    idx_msg->flags = flags;
+    idx_msg->dirty = TRUE;
     oh->dirty = TRUE;
 
     /* Set return value */
@@ -1391,6 +1406,206 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5O_protect
+ *
+ * Purpose:	Wrapper around H5AC_protect for use during a H5O_protect->
+ *              H5O_append->...->H5O_append->H5O_unprotect sequence of calls
+ *              during an object's creation.
+ *
+ * Return:	Success:	Pointer to the object header structure for the
+ *                              object.
+ *
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@ncsa.uiuc.edu
+ *		Dec 31 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+H5O_t *
+H5O_protect(H5G_entry_t *ent)
+{
+    H5O_t	       *ret_value;      /* Return value */
+
+    FUNC_ENTER_NOAPI(H5O_protect, NULL);
+
+    /* check args */
+    assert(ent);
+    assert(ent->file);
+    assert(H5F_addr_defined(ent->header));
+
+    if (0==(ent->file->intent & H5F_ACC_RDWR))
+	HGOTO_ERROR (H5E_OHDR, H5E_WRITEERROR, NULL, "no write intent on file");
+
+    if (NULL == (ret_value = H5AC_protect(ent->file, H5AC_OHDR, ent->header, NULL, NULL)))
+	HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "unable to load object header");
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5O_protect() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5O_unprotect
+ *
+ * Purpose:	Wrapper around H5AC_unprotect for use during a H5O_protect->
+ *              H5O_append->...->H5O_append->H5O_unprotect sequence of calls
+ *              during an object's creation.
+ *
+ * Return:	Success:	Non-negative
+ *
+ *		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@ncsa.uiuc.edu
+ *		Dec 31 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5O_unprotect(H5G_entry_t *ent, H5O_t *oh)
+{
+    herr_t ret_value=SUCCEED;      /* Return value */
+
+    FUNC_ENTER_NOAPI(H5O_unprotect, FAIL);
+
+    /* check args */
+    assert(ent);
+    assert(ent->file);
+    assert(H5F_addr_defined(ent->header));
+    assert(oh);
+
+    if (H5AC_unprotect(ent->file, H5AC_OHDR, ent->header, oh) < 0)
+	HDONE_ERROR(H5E_OHDR, H5E_PROTECT, FAIL, "unable to release object header");
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5O_unprotect() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5O_append
+ *
+ * Purpose:	Simplified version of H5O_modify, used when creating a new
+ *              object header message (usually during object creation)
+ *
+ *              Modifies an existing message or creates a new message.
+ *		The cache fields in that symbol table entry ENT are *not*
+ *		updated, you must do that separately because they often
+ *		depend on multiple object header messages.  Besides, we
+ *		don't know which messages will be constant and which will
+ *		not.
+ *
+ * Return:	Success:	The sequence number of the message that
+ *				was created.
+ *
+ *		Failure:	Negative
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@ncsa.uiuc.edu
+ *		Dec 31 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+int
+H5O_append(H5F_t *f, H5O_t *oh, const H5O_class_t *type, 
+    unsigned flags, const void *mesg)
+{
+    unsigned		idx;            /* Index of message to modify */
+    H5O_mesg_t         *idx_msg;        /* Pointer to message to modify */
+    int		        ret_value = FAIL;
+    size_t		size=0;
+    H5O_shared_t	sh_mesg;
+
+    FUNC_ENTER_NOAPI(H5O_append, FAIL);
+
+    /* check args */
+    assert(f);
+    assert(oh);
+    assert(type);
+    assert(0==(flags & ~H5O_FLAG_BITS));
+    assert(mesg);
+
+    /* Allocate space for the new message */
+    if (flags & H5O_FLAG_SHARED) {
+        HDmemset(&sh_mesg,0,sizeof(H5O_shared_t));
+
+        if (NULL==type->get_share)
+            HGOTO_ERROR (H5E_OHDR, H5E_UNSUPPORTED, FAIL, "message class is not sharable");
+        if ((type->get_share)(f, mesg, &sh_mesg/*out*/)<0) {
+            /*
+             * If the message isn't shared then turn off the shared bit
+             * and treat it as an unshared message.
+             */
+            H5E_clear ();
+            flags &= ~H5O_FLAG_SHARED;
+        } else if (sh_mesg.in_gh) {
+            /*
+             * The shared message is stored in the global heap.
+             * Increment the reference count on the global heap message.
+             */
+            if (H5HG_link (f, &(sh_mesg.u.gh), 1)<0)
+                HGOTO_ERROR (H5E_OHDR, H5E_LINK, FAIL, "unable to adjust shared object link count");
+            size = (H5O_SHARED->raw_size)(f, &sh_mesg);
+        } else {
+            /*
+             * The shared message is stored in some other object header.
+             * The other object header must be in the same file as the
+             * new object header. Increment the reference count on that
+             * object header.
+             */
+            if (sh_mesg.u.ent.file->shared != f->shared)
+                HGOTO_ERROR(H5E_OHDR, H5E_LINK, FAIL, "interfile hard links are not allowed");
+            if (H5O_link (&(sh_mesg.u.ent), 1)<0)
+                HGOTO_ERROR (H5E_OHDR, H5E_LINK, FAIL, "unable to adjust shared object link count");
+            size = (H5O_SHARED->raw_size)(f, &sh_mesg);
+        }
+    }
+    /* This can't be an 'else' statement due to the possibility of the shared bit getting turned off above */
+    if (0== (flags & H5O_FLAG_SHARED)) {
+        size = (type->raw_size) (f, mesg);
+        if (size>=H5O_MAX_SIZE)
+            HGOTO_ERROR (H5E_OHDR, H5E_CANTINIT, FAIL, "object header message is too large (16k max)");
+    }
+    if ((idx = H5O_alloc(f, oh, type, size)) == UFAIL)
+        HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to allocate space for message");
+        
+    /* Set pointer to the correct message */
+    idx_msg=&oh->mesg[idx];
+
+    /* Copy the native value into the object header */
+    if (flags & H5O_FLAG_SHARED) {
+        if (NULL==(idx_msg->native = H5MM_malloc (sizeof (H5O_shared_t))))
+            HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
+        HDmemcpy(idx_msg->native,&sh_mesg,sizeof(H5O_shared_t));
+    } else {
+	if (idx_msg->native)
+	    H5O_reset (idx_msg->type, idx_msg->native);
+	idx_msg->native = (type->copy) (mesg, idx_msg->native);
+	if (NULL == idx_msg->native)
+	    HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to copy message to object header");
+    }
+    
+    idx_msg->flags = flags;
+    idx_msg->dirty = TRUE;
+    oh->dirty = TRUE;
+
+    /* Set return value */
+    ret_value = idx;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5O_append() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5O_touch_oh
  *
  * Purpose:	If FORCE is non-zero then create a modification time message
@@ -1406,11 +1621,14 @@ done:
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
+herr_t
 H5O_touch_oh(H5F_t *f, H5O_t *oh, hbool_t force)
 {
     unsigned	idx;
-    time_t	now = HDtime(NULL);
+#ifdef H5_HAVE_GETTIMEOFDAY
+    struct timeval now_tv;
+#endif /* H5_HAVE_GETTIMEOFDAY */
+    time_t	now;
     size_t	size;
     herr_t      ret_value=SUCCEED;       /* Return value */
     
@@ -1420,22 +1638,29 @@ H5O_touch_oh(H5F_t *f, H5O_t *oh, hbool_t force)
 
     /* Look for existing message */
     for (idx=0; idx<oh->nmesgs; idx++) {
-	if (H5O_MTIME==oh->mesg[idx].type)
+	if (H5O_MTIME==oh->mesg[idx].type || H5O_MTIME_NEW==oh->mesg[idx].type)
             break;
     }
 
+#ifdef H5_HAVE_GETTIMEOFDAY
+    HDgettimeofday(&now_tv,NULL);
+    now=now_tv.tv_sec;
+#else /* H5_HAVE_GETTIMEOFDAY */
+    now = HDtime(NULL);
+#endif /* H5_HAVE_GETTIMEOFDAY */
+
     /* Create a new message */
     if (idx==oh->nmesgs) {
 	if (!force)
             HGOTO_DONE(SUCCEED); /*nothing to do*/
-	size = (H5O_MTIME->raw_size)(f, &now);
-	if ((idx=H5O_alloc(f, oh, H5O_MTIME, size))==UFAIL)
+	size = (H5O_MTIME_NEW->raw_size)(f, &now);
+	if ((idx=H5O_alloc(f, oh, H5O_MTIME_NEW, size))==UFAIL)
 	    HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to allocate space for modification time message");
     }
 
     /* Update the native part */
     if (NULL==oh->mesg[idx].native) {
-	if (NULL==(oh->mesg[idx].native = H5FL_ALLOC(time_t,0)))
+	if (NULL==(oh->mesg[idx].native = H5FL_MALLOC(time_t)))
 	    HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "memory allocation failed for modification time message");
     }
     *((time_t*)(oh->mesg[idx].native)) = now;
@@ -1833,7 +2058,7 @@ H5O_alloc_new_chunk(H5F_t *f, H5O_t *oh, size_t size)
     oh->chunk[chunkno].dirty = TRUE;
     oh->chunk[chunkno].addr = HADDR_UNDEF;
     oh->chunk[chunkno].size = size;
-    if (NULL==(oh->chunk[chunkno].image = p = H5FL_BLK_ALLOC(chunk_image,size,1)))
+    if (NULL==(oh->chunk[chunkno].image = p = H5FL_BLK_CALLOC(chunk_image,size)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, UFAIL, "memory allocation failed");
     
     /*
@@ -1944,9 +2169,8 @@ done:
 static unsigned
 H5O_alloc(H5F_t *f, H5O_t *oh, const H5O_class_t *type, size_t size)
 {
-    unsigned	chunkno;
     unsigned	idx;
-    unsigned	null_idx;
+    H5O_mesg_t *msg;            /* Pointer to newly allocated message */
     size_t	aligned_size = H5O_ALIGN(size);
     unsigned	ret_value;      /* Return value */
 
@@ -1975,6 +2199,8 @@ H5O_alloc(H5F_t *f, H5O_t *oh, const H5O_class_t *type, size_t size)
 
     /* if we didn't find one, then allocate more header space */
     if (idx >= oh->nmesgs) {
+        unsigned	chunkno;
+
 	/*
 	 * Look for a chunk which hasn't had disk space allocated yet
 	 * since we can just increase the size of that chunk.
@@ -1995,9 +2221,15 @@ H5O_alloc(H5F_t *f, H5O_t *oh, const H5O_class_t *type, size_t size)
 	}
     }
 
+    /* Set pointer to newly allocated message */
+    msg=&oh->mesg[idx];
+
     /* do we need to split the null message? */
-    if (oh->mesg[idx].raw_size > aligned_size) {
-	assert(oh->mesg[idx].raw_size - aligned_size >= H5O_SIZEOF_MSGHDR(f));
+    if (msg->raw_size > aligned_size) {
+        H5O_mesg_t *null_msg;       /* Pointer to null message */
+        size_t	mesg_size = aligned_size+ H5O_SIZEOF_MSGHDR(f); /* Total size of newly allocated message */
+
+	assert(msg->raw_size - aligned_size >= H5O_SIZEOF_MSGHDR(f));
 
 	if (oh->nmesgs >= oh->alloc_nmesgs) {
 	    int old_alloc=oh->alloc_nmesgs;
@@ -2013,23 +2245,20 @@ H5O_alloc(H5F_t *f, H5O_t *oh, const H5O_class_t *type, size_t size)
 	    HDmemset(&oh->mesg[old_alloc],0,
 		     (oh->alloc_nmesgs-old_alloc)*sizeof(H5O_mesg_t));
 	}
-	null_idx = oh->nmesgs++;
-	oh->mesg[null_idx].type = H5O_NULL;
-	oh->mesg[null_idx].dirty = TRUE;
-	oh->mesg[null_idx].native = NULL;
-	oh->mesg[null_idx].raw = oh->mesg[idx].raw +
-				 aligned_size +
-				 H5O_SIZEOF_MSGHDR(f);
-	oh->mesg[null_idx].raw_size = oh->mesg[idx].raw_size -
-				      (aligned_size + H5O_SIZEOF_MSGHDR(f));
-	oh->mesg[null_idx].chunkno = oh->mesg[idx].chunkno;
-	oh->mesg[idx].raw_size = aligned_size;
+        null_msg=&oh->mesg[oh->nmesgs++];
+	null_msg->type = H5O_NULL;
+	null_msg->dirty = TRUE;
+	null_msg->native = NULL;
+	null_msg->raw = msg->raw + mesg_size;
+	null_msg->raw_size = msg->raw_size - mesg_size;
+	null_msg->chunkno = msg->chunkno;
+	msg->raw_size = aligned_size;
     }
 
     /* initialize the new message */
-    oh->mesg[idx].type = type;
-    oh->mesg[idx].dirty = TRUE;
-    oh->mesg[idx].native = NULL;
+    msg->type = type;
+    msg->dirty = TRUE;
+    msg->native = NULL;
 
     oh->dirty = TRUE;
 
diff --git a/src/H5Oattr.c b/src/H5Oattr.c
index 40da90a..34e209a 100644
--- a/src/H5Oattr.c
+++ b/src/H5Oattr.c
@@ -134,14 +134,23 @@ H5O_attr_decode(H5F_t *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
     p += H5O_ALIGN(attr->dt_size);
 
     /* decode the attribute dataspace */
-    if (NULL==(attr->ds = H5FL_ALLOC(H5S_t,1)))
+    if (NULL==(attr->ds = H5FL_CALLOC(H5S_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     if((simple=(H5O_SDSPACE->decode)(f,p,NULL))!=NULL) {
+        hsize_t nelem;  /* Number of elements in extent */
+        unsigned u;     /* Local index variable */
+
         attr->ds->extent.type = H5S_SIMPLE;
         HDmemcpy(&(attr->ds->extent.u.simple),simple, sizeof(H5S_simple_t));
         H5FL_FREE(H5S_simple_t,simple);
+
+        /* Compute the number of elements in the extent */
+        for(u=0, nelem=1; u<attr->ds->extent.u.simple.rank; u++)
+            nelem*=attr->ds->extent.u.simple.size[u];
+        attr->ds->extent.nelem = nelem;
     } else {
         attr->ds->extent.type = H5S_SCALAR;
+        attr->ds->extent.nelem = 1;
     }
     /* Default to entire dataspace being selected */
     if(H5S_select_all(attr->ds,0)<0)
diff --git a/src/H5Odtype.c b/src/H5Odtype.c
index 1d8b254..4244c41 100644
--- a/src/H5Odtype.c
+++ b/src/H5Odtype.c
@@ -48,7 +48,7 @@ const H5O_class_t H5O_DTYPE[1] = {{
     H5O_dtype_copy,		/* copy the native value	*/
     H5O_dtype_size,		/* size of raw message		*/
     H5O_dtype_reset,		/* reset method			*/
-    H5O_dtype_free,		    /* free method			*/
+    H5O_dtype_free,		/* free method			*/
     H5O_dtype_get_share,	/* get share method		*/
     H5O_dtype_set_share,	/* set share method		*/
     H5O_dtype_debug,		/* debug the message		*/
@@ -227,7 +227,7 @@ H5O_dtype_decode_helper(H5F_t *f, const uint8_t **pp, H5T_t *dt)
                 } /* end if */
 
                 /* Allocate space for the field's datatype */
-                temp_type = H5FL_ALLOC (H5T_t,1);
+                temp_type = H5FL_CALLOC (H5T_t);
                 if (NULL==temp_type)
                     HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
                 temp_type->ent.header = HADDR_UNDEF;
@@ -289,7 +289,7 @@ H5O_dtype_decode_helper(H5F_t *f, const uint8_t **pp, H5T_t *dt)
              */
             dt->u.enumer.nmembs = dt->u.enumer.nalloc = flags & 0xffff;
             assert(dt->u.enumer.nmembs>=0);
-            if (NULL==(dt->parent=H5FL_ALLOC(H5T_t,1)))
+            if (NULL==(dt->parent=H5FL_CALLOC(H5T_t)))
                 HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
             dt->parent->ent.header = HADDR_UNDEF;
             if (H5O_dtype_decode_helper(f, pp, dt->parent)<0)
@@ -343,7 +343,7 @@ H5O_dtype_decode_helper(H5F_t *f, const uint8_t **pp, H5T_t *dt)
             } /* end if */
 
             /* Decode base type of VL information */
-            if (NULL==(dt->parent = H5FL_ALLOC(H5T_t,1)))
+            if (NULL==(dt->parent = H5FL_CALLOC(H5T_t)))
                 HGOTO_ERROR (H5E_DATATYPE, H5E_NOSPACE, FAIL, "memory allocation failed");
             dt->parent->ent.header = HADDR_UNDEF;
             if (H5O_dtype_decode_helper(f, pp, dt->parent)<0)
@@ -381,7 +381,7 @@ H5O_dtype_decode_helper(H5F_t *f, const uint8_t **pp, H5T_t *dt)
                 UINT32DECODE(*pp, dt->u.array.perm[j]);
 
             /* Decode base type of array */
-            if (NULL==(dt->parent = H5FL_ALLOC(H5T_t,1)))
+            if (NULL==(dt->parent = H5FL_CALLOC(H5T_t)))
                 HGOTO_ERROR (H5E_DATATYPE, H5E_NOSPACE, FAIL, "memory allocation failed");
             dt->parent->ent.header = HADDR_UNDEF;
             if (H5O_dtype_decode_helper(f, pp, dt->parent)<0)
@@ -794,7 +794,7 @@ H5O_dtype_decode(H5F_t *f, const uint8_t *p,
     /* check args */
     assert(p);
 
-    if (NULL==(dt = H5FL_ALLOC(H5T_t,1)))
+    if (NULL==(dt = H5FL_CALLOC(H5T_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     dt->ent.header = HADDR_UNDEF;
 
@@ -1009,18 +1009,12 @@ static herr_t
 H5O_dtype_reset(void *_mesg)
 {
     H5T_t		   *dt = (H5T_t *) _mesg;
-    H5T_t		   *tmp = NULL;
     herr_t      ret_value=SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5O_dtype_reset, FAIL);
 
-    if (dt) {
-        if (NULL==(tmp = H5FL_ALLOC(H5T_t,0)))
-            HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
-        *tmp = *dt;
-        H5T_close(tmp);
-        HDmemset(dt, 0, sizeof(H5T_t));
-    }
+    if (dt)
+        H5T_free(dt);
 
 done:
     FUNC_LEAVE(ret_value);
@@ -1130,8 +1124,8 @@ H5O_dtype_set_share (H5F_t UNUSED *f, void *_mesg/*in,out*/,
     H5G_ent_copy(&(dt->ent),&(sh->u.ent),H5G_COPY_SHALLOW);
 
     /* Reset the names of the copied symbol table entry */
-    dt->ent.user_path = NULL;
-    dt->ent.canon_path = NULL;
+    dt->ent.user_path_r = NULL;
+    dt->ent.canon_path_r = NULL;
 
     /* Note that the datatype is a named datatype */
     dt->state = H5T_STATE_NAMED;
diff --git a/src/H5Oefl.c b/src/H5Oefl.c
index 388aa4a..c81002b 100644
--- a/src/H5Oefl.c
+++ b/src/H5Oefl.c
@@ -341,7 +341,8 @@ H5O_efl_reset(void *_mesg)
 	mesg->slot[i].name = H5MM_xfree (mesg->slot[i].name);
     mesg->heap_addr = HADDR_UNDEF;
     mesg->nused = mesg->nalloc = 0;
-    mesg->slot = H5MM_xfree(mesg->slot);
+    if(mesg->slot)
+        mesg->slot = H5MM_xfree(mesg->slot);
 
 done:
     FUNC_LEAVE(ret_value);
diff --git a/src/H5Ofill.c b/src/H5Ofill.c
index dd734b9..92d2000 100644
--- a/src/H5Ofill.c
+++ b/src/H5Ofill.c
@@ -10,6 +10,7 @@
  */
 #include "H5private.h"
 #include "H5Eprivate.h"
+#include "H5FLprivate.h"	/*Free Lists	  */
 #include "H5Iprivate.h"
 #include "H5MMprivate.h"
 #include "H5Oprivate.h"
@@ -22,6 +23,7 @@ static herr_t H5O_fill_new_encode(H5F_t *f, uint8_t *p, const void *_mesg);
 static void  *H5O_fill_new_copy(const void *_mesg, void *_dest);
 static size_t H5O_fill_new_size(H5F_t *f, const void *_mesg);
 static herr_t H5O_fill_new_reset(void *_mesg);
+static herr_t H5O_fill_new_free(void *_mesg);
 static herr_t H5O_fill_new_debug(H5F_t *f, const void *_mesg, FILE *stream,
 			     int indent, int fwidth);
 
@@ -30,6 +32,7 @@ static herr_t H5O_fill_encode(H5F_t *f, uint8_t *p, const void *_mesg);
 static void  *H5O_fill_copy(const void *_mesg, void *_dest);
 static size_t H5O_fill_size(H5F_t *f, const void *_mesg);
 static herr_t H5O_fill_reset(void *_mesg);
+static herr_t H5O_fill_free(void *_mesg);
 static herr_t H5O_fill_debug(H5F_t *f, const void *_mesg, FILE *stream,
 			     int indent, int fwidth);
 
@@ -43,7 +46,7 @@ const H5O_class_t H5O_FILL[1] = {{
     H5O_fill_copy,              /*copy the native value                 */
     H5O_fill_size,              /*raw message size                      */
     H5O_fill_reset,             /*free internal memory                  */
-    NULL,                       /* free method   	                */
+    H5O_fill_free,		/* free method			*/
     NULL,                       /*get share method                      */
     NULL,                       /*set share method                      */
     H5O_fill_debug,             /*debug the message                     */
@@ -59,7 +62,7 @@ const H5O_class_t H5O_FILL_NEW[1] = {{
     H5O_fill_new_copy,		/*copy the native value			*/
     H5O_fill_new_size,		/*raw message size			*/
     H5O_fill_new_reset,		/*free internal memory			*/
-    NULL,		        /* free method				*/
+    H5O_fill_new_free,		/* free method			*/
     NULL,			/*get share method			*/
     NULL,			/*set share method			*/
     H5O_fill_new_debug,		/*debug the message			*/
@@ -71,6 +74,12 @@ const H5O_class_t H5O_FILL_NEW[1] = {{
 static int interface_initialize_g = 0;
 #define INTERFACE_INIT NULL
 
+/* Declare a free list to manage the H5O_fill_new_t struct */
+H5FL_DEFINE(H5O_fill_new_t);
+
+/* Declare a free list to manage the H5O_fill_t struct */
+H5FL_DEFINE(H5O_fill_t);
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5O_fill_new_decode
@@ -104,7 +113,7 @@ H5O_fill_new_decode(H5F_t UNUSED *f, const uint8_t *p,
     assert(p);
     assert(!sh);
 
-    if (NULL==(mesg=H5MM_calloc(sizeof(H5O_fill_new_t))))
+    if (NULL==(mesg=H5FL_CALLOC(H5O_fill_new_t)))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for fill value message");
  
     /* Version */
@@ -137,7 +146,7 @@ done:
     if (!ret_value && mesg) {
         if(mesg->buf)
             H5MM_xfree(mesg->buf);
-	H5MM_xfree(mesg);
+	H5FL_FREE(H5O_fill_new_t,mesg);
     }
 
     FUNC_LEAVE(ret_value);
@@ -173,7 +182,7 @@ H5O_fill_decode(H5F_t UNUSED *f, const uint8_t *p,
     assert(p);
     assert(!sh);
 
-    if (NULL==(mesg=H5MM_calloc(sizeof(H5O_fill_t))))
+    if (NULL==(mesg=H5FL_CALLOC(H5O_fill_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for fill value message");
     UINT32DECODE(p, mesg->size);
     if (mesg->size>0) {
@@ -189,7 +198,7 @@ done:
     if (!ret_value && mesg) {
         if(mesg->buf)
             H5MM_xfree(mesg->buf);
-        H5MM_xfree(mesg);
+	H5FL_FREE(H5O_fill_t,mesg);
     }
 
     FUNC_LEAVE(ret_value);
@@ -311,13 +320,16 @@ H5O_fill_new_copy(const void *_mesg, void *_dest)
 
     assert(mesg);
 
-    if (!dest && NULL==(dest=H5MM_calloc(sizeof(H5O_fill_new_t))))
+    if (!dest && NULL==(dest=H5FL_MALLOC(H5O_fill_new_t)))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for fill message");
 
     /* Copy data type of fill value */
-    if (mesg->type &&
-            NULL==(dest->type=H5T_copy(mesg->type, H5T_COPY_TRANSIENT)))
-	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "unable to copy fill value data type");
+    if (mesg->type) {
+        if(NULL==(dest->type=H5T_copy(mesg->type, H5T_COPY_TRANSIENT)))
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "unable to copy fill value data type");
+    } /* end if */
+    else
+        dest->type=NULL;
 
     /* Copy fill value and its size */
     if (mesg->buf) {
@@ -326,7 +338,11 @@ H5O_fill_new_copy(const void *_mesg, void *_dest)
 	    HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for fill value");
 	dest->size = mesg->size;
 	HDmemcpy(dest->buf, mesg->buf, (size_t)mesg->size);
-    }
+    } /* end if */
+    else {
+        dest->buf=NULL;
+        dest->size=0;
+    } /* end else */
 
     /* Copy three fill value attributes */
     dest->alloc_time   = mesg->alloc_time;
@@ -343,7 +359,7 @@ done:
 	if (dest->type)
             H5T_close(dest->type);
 	if (!_dest)
-            H5MM_xfree(dest);
+            H5FL_FREE(H5O_fill_new_t,dest);
     }
 
     FUNC_LEAVE(ret_value);
@@ -378,17 +394,24 @@ H5O_fill_copy(const void *_mesg, void *_dest)
 
     assert(mesg);
 
-    if (!dest && NULL==(dest=H5MM_calloc(sizeof(H5O_fill_t))))
+    if (!dest && NULL==(dest=H5FL_CALLOC(H5O_fill_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for fill message");
-    if (mesg->type &&
-            NULL==(dest->type=H5T_copy(mesg->type, H5T_COPY_TRANSIENT)))
-        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "unable to copy fill value data type");
+
+    if (mesg->type) {
+        if(NULL==(dest->type=H5T_copy(mesg->type, H5T_COPY_TRANSIENT)))
+            HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "unable to copy fill value data type");
+    } /* end if */
+    else
+        dest->type=NULL;
+
     if (mesg->buf) {
         if (NULL==(dest->buf=H5MM_malloc(mesg->size)))
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for fill value");
         dest->size = mesg->size;
         HDmemcpy(dest->buf, mesg->buf, mesg->size);
-    }
+    } /* end if */
+    else
+        dest->buf=NULL;
 
     /* Set return value */
     ret_value = dest;
@@ -400,7 +423,7 @@ done:
         if (dest->type)
             H5T_close(dest->type);
         if (!_dest)
-            H5MM_xfree(dest);
+            H5FL_FREE(H5O_fill_t,dest);
     }
 
     FUNC_LEAVE(ret_value);
@@ -567,6 +590,66 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5O_fill_new_free
+ *
+ * Purpose:	Free's the message
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, December 5, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5O_fill_new_free (void *mesg)
+{
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5O_fill_new_free, FAIL);
+
+    assert (mesg);
+
+    H5FL_FREE(H5O_fill_new_t,mesg);
+
+done:
+    FUNC_LEAVE (ret_value);
+}
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5O_fill_free
+ *
+ * Purpose:	Free's the message
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, December 5, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5O_fill_free (void *mesg)
+{
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5O_fill_free, FAIL);
+
+    assert (mesg);
+
+    H5FL_FREE(H5O_fill_t,mesg);
+
+done:
+    FUNC_LEAVE (ret_value);
+}
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5O_fill_new_debug
  *
  * Purpose:	Prints debugging info for the message.
@@ -721,7 +804,7 @@ H5O_fill_convert(void *_fill, H5T_t *dset_type)
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for type conversion");
 
     /* Do the conversion */
-    if (H5T_convert(tpath, src_id, dst_id, (hsize_t)1, 0, 0, buf, bkg, H5P_DEFAULT)<0)
+    if (H5T_convert(tpath, src_id, dst_id, (hsize_t)1, 0, 0, buf, bkg, H5P_DATASET_XFER_DEFAULT)<0)
 	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "data type conversion failed");
 
     /* Update the fill message */
diff --git a/src/H5Ofphdf5.c b/src/H5Ofphdf5.c
index 5b4afb3..a35d001 100644
--- a/src/H5Ofphdf5.c
+++ b/src/H5Ofphdf5.c
@@ -107,7 +107,7 @@ H5O_fphdf5_decode(H5F_t *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
     assert(!sh);
 
     /* decode */
-    fmeta = H5FL_ALLOC(H5O_fphdf5_t, 1);
+    fmeta = H5FL_CALLOC(H5O_fphdf5_t);
 
     /* decode the OID first */
     NBYTEDECODE(p, fmeta->oid, sizeof(fmeta->oid));
@@ -333,7 +333,7 @@ H5O_fphdf5_copy(const void *mesg, void *dest)
     /* check args */
     assert(src);
 
-    if (!dst && NULL == (dst = H5FL_ALLOC(H5O_fphdf5_t, 0)))
+    if (!dst && NULL == (dst = H5FL_MALLOC(H5O_fphdf5_t)))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* copy the individual metadata*/
diff --git a/src/H5Olayout.c b/src/H5Olayout.c
index 8be6627..41c173e 100644
--- a/src/H5Olayout.c
+++ b/src/H5Olayout.c
@@ -93,7 +93,7 @@ H5O_layout_decode(H5F_t *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
     assert (!sh);
 
     /* decode */
-    if (NULL==(mesg = H5FL_ALLOC(H5O_layout_t,1)))
+    if (NULL==(mesg = H5FL_CALLOC(H5O_layout_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* Version. 1 when space allocated; 2 when space allocation is delayed */
@@ -248,7 +248,7 @@ H5O_layout_copy(const void *_mesg, void *_dest)
 
     /* check args */
     assert(mesg);
-    if (!dest && NULL==(dest=H5FL_ALLOC(H5O_layout_t,0)))
+    if (!dest && NULL==(dest=H5FL_MALLOC(H5O_layout_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     
     /* copy */
@@ -387,7 +387,7 @@ H5O_layout_reset (void *_mesg)
             mesg->buf=H5MM_xfree(mesg->buf);
 
         /* Reset the message */
-        HDmemset(mesg, 0, sizeof(H5O_layout_t));
+        mesg->type=H5D_CONTIGUOUS;
     } /* end if */
 
 done:
diff --git a/src/H5Omtime.c b/src/H5Omtime.c
index e31dece..ff3eb5a 100644
--- a/src/H5Omtime.c
+++ b/src/H5Omtime.c
@@ -20,11 +20,16 @@
 
 #define PABLO_MASK	H5O_mtime_mask
 
+static void *H5O_mtime_new_decode(H5F_t *f, const uint8_t *p, H5O_shared_t *sh);
+static herr_t H5O_mtime_new_encode(H5F_t *f, uint8_t *p, const void *_mesg);
+static size_t H5O_mtime_new_size(H5F_t *f, const void *_mesg);
+
 static void *H5O_mtime_decode(H5F_t *f, const uint8_t *p, H5O_shared_t *sh);
 static herr_t H5O_mtime_encode(H5F_t *f, uint8_t *p, const void *_mesg);
 static void *H5O_mtime_copy(const void *_mesg, void *_dest);
 static size_t H5O_mtime_size(H5F_t *f, const void *_mesg);
-static herr_t H5O_mtime_free (void *_mesg);
+static herr_t H5O_mtime_reset(void *_mesg);
+static herr_t H5O_mtime_free(void *_mesg);
 static herr_t H5O_mtime_debug(H5F_t *f, const void *_mesg, FILE *stream,
 			     int indent, int fwidth);
 
@@ -37,8 +42,25 @@ const H5O_class_t H5O_MTIME[1] = {{
     H5O_mtime_encode,		/*encode message		*/
     H5O_mtime_copy,		/*copy the native value		*/
     H5O_mtime_size,		/*raw message size		*/
-    NULL,			/*free internal memory		*/
-    H5O_mtime_free,		            /* free method			*/
+    H5O_mtime_reset,		/* reset method			*/
+    H5O_mtime_free,		/* free method			*/
+    NULL,			/*get share method		*/
+    NULL,			/*set share method		*/
+    H5O_mtime_debug,		/*debug the message		*/
+}};
+
+/* This message derives from H5O */
+/* (Only encode, decode & size routines are different from old mtime routines) */
+const H5O_class_t H5O_MTIME_NEW[1] = {{
+    H5O_MTIME_NEW_ID,		/*message id number		*/
+    "mtime_new",		/*message name for debugging	*/
+    sizeof(time_t),		/*native message size		*/
+    H5O_mtime_new_decode,	/*decode message		*/
+    H5O_mtime_new_encode,	/*encode message		*/
+    H5O_mtime_copy,		/*copy the native value		*/
+    H5O_mtime_new_size,		/*raw message size		*/
+    H5O_mtime_reset,		/* reset method			*/
+    H5O_mtime_free,		/* free method			*/
     NULL,			/*get share method		*/
     NULL,			/*set share method		*/
     H5O_mtime_debug,		/*debug the message		*/
@@ -48,11 +70,74 @@ const H5O_class_t H5O_MTIME[1] = {{
 static int interface_initialize_g = 0;
 #define INTERFACE_INIT	NULL
 
+/* Current version of new mtime information */
+#define H5O_MTIME_VERSION 	1	
+ 
+/* Track whether tzset routine was called */
+static int	ntzset=0;
+
 /* Declare a free list to manage the time_t struct */
 H5FL_DEFINE(time_t);
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5O_mtime_new_decode
+ *
+ * Purpose:	Decode a new modification time message and return a pointer to a
+ *		new time_t value.
+ *
+ * Return:	Success:	Ptr to new message in native struct.
+ *
+ *		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@ncsa.uiuc.edu
+ *		Jan  3 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static void *
+H5O_mtime_new_decode(H5F_t UNUSED *f, const uint8_t *p,
+		 H5O_shared_t UNUSED *sh)
+{
+    time_t	*mesg, the_time;
+    int		version;        /* Version of mtime information */
+    void        *ret_value;     /* Return value */
+
+    FUNC_ENTER_NOAPI(H5O_mtime_new_decode, NULL);
+
+    /* check args */
+    assert(f);
+    assert(p);
+    assert (!sh);
+
+    /* decode */
+    version = *p++;
+    if(version!=H5O_MTIME_VERSION)
+        HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "bad version number for mtime message");
+
+    /* Skip reserved bytes */
+    p+=3;
+
+    /* Get the time_t from the file */
+    UINT32DECODE(p, the_time);
+
+    /* The return value */
+    if (NULL==(mesg = H5FL_MALLOC(time_t)))
+	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
+    *mesg = the_time;
+
+    /* Set return value */
+    ret_value=mesg;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5O_mtime_new_decode() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5O_mtime_decode
  *
  * Purpose:	Decode a modification time message and return a pointer to a
@@ -77,7 +162,6 @@ H5O_mtime_decode(H5F_t UNUSED *f, const uint8_t *p,
     time_t	*mesg, the_time;
     int	i;
     struct tm	tm;
-    static int	ncalls=0;
     void        *ret_value;     /* Return value */
 
     FUNC_ENTER_NOAPI(H5O_mtime_decode, NULL);
@@ -88,7 +172,10 @@ H5O_mtime_decode(H5F_t UNUSED *f, const uint8_t *p,
     assert (!sh);
 
     /* Initialize time zone information */
-    if (0==ncalls++) HDtzset();
+    if (!ntzset) {
+        HDtzset();
+        ntzset=1;
+    } /* end if */
 
     /* decode */
     for (i=0; i<14; i++) {
@@ -166,7 +253,7 @@ H5O_mtime_decode(H5F_t UNUSED *f, const uint8_t *p,
 #endif
     
     /* The return value */
-    if (NULL==(mesg = H5FL_ALLOC(time_t,1)))
+    if (NULL==(mesg = H5FL_MALLOC(time_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     *mesg = the_time;
 
@@ -179,6 +266,50 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5O_mtime_new_encode
+ *
+ * Purpose:	Encodes a new modification time message.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@ncsa.uiuc.edu
+ *		Jan  3 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5O_mtime_new_encode(H5F_t UNUSED *f, uint8_t *p, const void *_mesg)
+{
+    const time_t	*mesg = (const time_t *) _mesg;
+    herr_t ret_value=SUCCEED;   /* Return value */
+    
+    FUNC_ENTER_NOAPI(H5O_mtime_new_encode, FAIL);
+
+    /* check args */
+    assert(f);
+    assert(p);
+    assert(mesg);
+
+    /* Version */
+    *p++ = H5O_MTIME_VERSION;
+
+    /* Reserved bytes */
+    *p++ = 0;
+    *p++ = 0;
+    *p++ = 0;
+
+    /* Encode time */
+    UINT32ENCODE(p, *mesg);
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5O_mtime_new_encode() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5O_mtime_encode
  *
  * Purpose:	Encodes a modification time message.
@@ -247,7 +378,7 @@ H5O_mtime_copy(const void *_mesg, void *_dest)
 
     /* check args */
     assert(mesg);
-    if (!dest && NULL==(dest = H5FL_ALLOC(time_t,0)))
+    if (!dest && NULL==(dest = H5FL_MALLOC(time_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     
     /* copy */
@@ -262,6 +393,42 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5O_mtime_new_size
+ *
+ * Purpose:	Returns the size of the raw message in bytes not
+ *		counting the message type or size fields, but only the data
+ *		fields.	 This function doesn't take into account
+ *		alignment.
+ *
+ * Return:	Success:	Message data size in bytes w/o alignment.
+ *
+ *		Failure:	0
+ *
+ * Programmer:	Quincey Koziol
+ *		koziol@ncsa.uiuc.edu
+ *		Jan  3 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static size_t
+H5O_mtime_new_size(H5F_t * UNUSED f, const void * UNUSED mesg)
+{
+    size_t ret_value=8;        /* Return value */
+
+    FUNC_ENTER_NOAPI(H5O_mtime_new_size, 0);
+
+    /* check args */
+    assert(f);
+    assert(mesg);
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5O_mtime_new_size() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5O_mtime_size
  *
  * Purpose:	Returns the size of the raw message in bytes not
@@ -298,6 +465,33 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5O_mtime_reset
+ *
+ * Purpose:	Frees resources within a modification time message, but doesn't free
+ *		the message itself.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *		Mondey, December 23, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5O_mtime_reset(void UNUSED *_mesg)
+{
+    herr_t      ret_value=SUCCEED;       /* Return value */
+
+    FUNC_ENTER_NOAPI(H5O_mtime_reset, FAIL);
+
+done:
+    FUNC_LEAVE(ret_value);
+}
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5O_mtime_free
  *
  * Purpose:	Free's the message
diff --git a/src/H5Ocomp.c b/src/H5Opline.c
index 8899c34..eb42f5b 100644
--- a/src/H5Ocomp.c
+++ b/src/H5Opline.c
@@ -81,7 +81,7 @@ H5O_pline_decode(H5F_t UNUSED *f, const uint8_t *p,
     assert(p);
 
     /* Decode */
-    if (NULL==(pline = H5FL_ALLOC(H5O_pline_t,1)))
+    if (NULL==(pline = H5FL_CALLOC(H5O_pline_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     version = *p++;
     if (version!=H5O_PLINE_VERSION)
@@ -244,7 +244,7 @@ H5O_pline_copy (const void *_src, void *_dst/*out*/)
     
     FUNC_ENTER_NOAPI(H5O_pline_copy, NULL);
 
-    if (!dst && NULL==(dst = H5FL_ALLOC (H5O_pline_t,0)))
+    if (!dst && NULL==(dst = H5FL_MALLOC (H5O_pline_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     *dst = *src;
@@ -381,7 +381,8 @@ H5O_pline_reset (void *mesg)
         H5MM_xfree(pline->filter[i].name);
         H5MM_xfree(pline->filter[i].cd_values);
     }
-    H5MM_xfree(pline->filter);
+    if(pline->filter)
+        H5MM_xfree(pline->filter);
     HDmemset(pline, 0, sizeof *pline);
 
 done:
diff --git a/src/H5Oplist.c b/src/H5Oplist.c
index 554d0b7..352df06 100644
--- a/src/H5Oplist.c
+++ b/src/H5Oplist.c
@@ -65,6 +65,12 @@ static int interface_initialize_g = 0;
 /* Declare external the free list for hsize_t arrays */
 H5FL_ARR_EXTERN(hsize_t);
 
+/* Declare the external free list for the H5P_genprop_t struct */
+H5FL_EXTERN(H5P_genprop_t);
+
+/* Declare the external free list for the H5P_genplist_t struct */
+H5FL_EXTERN(H5P_genplist_t);
+
 #define UINT_ENCODE(dst, src)   \
         if (sizeof(src) == 2) {                 \
             UINT16ENCODE(dst, src);             \
@@ -131,7 +137,7 @@ H5O_plist_decode(H5F_t UNUSED *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
     H5P_genclass_t *pclass; /* property list class to modify        */
     hid_t new_plist_id;     /* property list ID of new list created */
     int version;            /* message version number               */
-    unsigned int i, nprops, hashsize;
+    unsigned int i, nprops;
     void *ret_value;
     
     FUNC_ENTER_NOAPI(H5O_plist_decode, NULL);
@@ -169,11 +175,9 @@ H5O_plist_decode(H5F_t UNUSED *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
         ++p;
 
     UINT_DECODE(p, nprops);
-    UINT_DECODE(p, hashsize);
 
     /* Allocate new property list */
-    if ((new_plist = H5MM_calloc(sizeof(H5P_genplist_t) +
-                                 ((hashsize - 1) * sizeof(H5P_genprop_t *)))) == NULL)
+    if ((new_plist = H5FL_CALLOC(H5P_genplist_t)) == NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* Initialize new property list */
@@ -183,7 +187,11 @@ H5O_plist_decode(H5F_t UNUSED *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
     new_plist->class_init = 0;  /* Initially, wait until the class
                                    callback finishes to set */
 
-    /* Create new property list */
+    /* Initialize the TBBT to hold the properties */
+    if((new_plist->props=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,NULL,"can't create TBBT for properties");
+
+    /* Insert properties into property list */
     for (i = 0; i < nprops; ++i) {
         H5P_genprop_t *tprop;
         unsigned str_len;
@@ -192,35 +200,19 @@ H5O_plist_decode(H5F_t UNUSED *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
          * Allocate and initialize the property structure which is going
          * to hold the information we're reading in.
          */
-        if (NULL == (tprop = H5MM_malloc(sizeof(H5P_genprop_t))))
+        if (NULL == (tprop = H5FL_CALLOC(H5P_genprop_t)))
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
-        tprop->create = NULL;
-        tprop->def_value = NULL;
-        tprop->set = NULL;
-        tprop->get = NULL;
-        tprop->del = NULL;
-        tprop->copy = NULL;
-        tprop->close = NULL;
-        tprop->next = NULL;
-
-        /* Grab the XORed value of the name and get the length of the name */
-        UINT_DECODE(p, tprop->xor_val);
+        /* Grab the length of the name */
         UINT_DECODE(p, str_len);
 
-        if (str_len) {
-            /* If there is a name, allocate space for it and copy */
-            if (NULL == (tprop->name = H5MM_malloc(str_len + 1))) {
-                H5MM_xfree(tprop);
-                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-            }
-
-            HDmemcpy(tprop->name, p, str_len + 1);
-            p += str_len + 1;
-        } else {
-            tprop->name = NULL;
-            ++p;
+        /* Allocate space for the name and copy it */
+        if (NULL == (tprop->name = H5MM_malloc(str_len + 1))) {
+            H5FL_FREE(H5P_genprop_t,tprop);
+            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
         }
+        HDmemcpy(tprop->name, p, str_len + 1);
+        p += str_len + 1;
 
         /* Grab the size of the "value" data */
         UINT_DECODE(p, tprop->size);
@@ -228,18 +220,21 @@ H5O_plist_decode(H5F_t UNUSED *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
         /* Allocate and memcpy the value part of the property. */
         if ((tprop->value = H5MM_malloc(tprop->size)) == NULL) {
             H5MM_xfree(tprop->name);
-            H5MM_xfree(tprop);
+            H5FL_FREE(H5P_genprop_t,tprop);
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
         }
 
         HDmemcpy(tprop->value, p, tprop->size);
         p += tprop->size;
 
+        /* Set the property's type */
+        tprop->type=H5P_PROP_WITHIN_LIST;
+
         /* Insert the initialized property into the property list */
-        if (H5P_add_prop(new_plist->props, new_plist->pclass->hashsize, tprop) < 0) {
+        if (H5P_add_prop(new_plist->props, tprop) < 0) {
             H5MM_xfree(tprop->value);
             H5MM_xfree(tprop->name);
-            H5MM_xfree(tprop);
+            H5FL_FREE(H5P_genprop_t,tprop);
             HGOTO_ERROR(H5E_PLIST, H5E_CANTINSERT, NULL, "Can't insert property into list");
         }
 
@@ -292,9 +287,8 @@ static herr_t
 H5O_plist_encode(H5F_t UNUSED *f, uint8_t *p, const void *mesg)
 {
     const H5P_genplist_t *plist = (const H5P_genplist_t *)mesg;
+    char *class_path;           /* Pointer to class path generated for property list */
     herr_t ret_value = SUCCEED;
-    unsigned int i;
-    char *class_path;
 
     FUNC_ENTER_NOAPI(H5O_plist_encode, FAIL);
 
@@ -333,45 +327,47 @@ H5O_plist_encode(H5F_t UNUSED *f, uint8_t *p, const void *mesg)
 
     HDfree(class_path);
     UINT_ENCODE(p, plist->nprops);
-    UINT_ENCODE(p, plist->pclass->hashsize);
 
-    for (i = 0; i < plist->pclass->hashsize; ++i) {
-        H5P_genprop_t *tprop = plist->props[i];
+    /* Encode the properties for this property list */
+    if(plist->nprops>0) {
+        H5TB_NODE *curr_node;   /* Current node in TBBT */
+        H5P_genprop_t *tprop;   /* Pointer to property */
+
+        /* Walk through the properties in the old class */
+        curr_node=H5TB_first(plist->props->root);
+        while(curr_node!=NULL) {
+            size_t s;           /* Length of property name */
 
-        /* Walk through the list of properties at each hash location */
-        while (tprop) {
-            const char *n = tprop->name;
+            /* Get a pointer to the property from the node */
+            tprop=curr_node->data;
+            assert(tprop->name);  /* Properties are guaranteed to have names */
 
             /*
              * Copy the meat of the generic property:
              *
-             *      1. The XORed version of the name
+             *      1. The length of the property name
              *      2. The name of the property
              *      3. The size of the property value
              *      4. The property value
              */
-            UINT_ENCODE(p, tprop->xor_val);
 
-            if (n && *n) {
-                size_t s = HDstrlen(n);
+            /* Get the name's length & encode it */
+            s = HDstrlen(tprop->name);
+            UINT_ENCODE(p, s);
 
-                UINT_ENCODE(p, s);
-                HDmemcpy(p, n, s + 1);
-                p += s + 1;
-            } else {
-                /* if there isn't a name, put a NULL there */
-                UINT_ENCODE(p, 0u);
-                *p++ = '\0';
-            }
+            /* Encode the name itself */
+            HDmemcpy(p, tprop->name, s + 1);
+            p += s + 1;
 
+            /* Encode the property value's size & data */
             UINT_ENCODE(p, tprop->size);
             HDmemcpy(p, tprop->value, tprop->size);
             p += tprop->size;
 
-            /* Go to next registered property in class */
-            tprop = tprop->next;
-        }
-    }
+            /* Get the next property node in the TBBT */
+            curr_node=H5TB_next(curr_node);
+        } /* end while */
+    } /* end if */
 
 done:
     FUNC_LEAVE(ret_value);
@@ -398,37 +394,17 @@ static size_t
 H5O_plist_size(H5F_t UNUSED *f, const void *mesg)
 {
     const H5P_genplist_t *plist = (const H5P_genplist_t *)mesg;
-    const H5P_genclass_t *pclass;
+    char *class_path=NULL;      /* Pointer to class path generated for property list */
     size_t ret_value;
-    char *class_path = NULL;
-    unsigned i;
 
     FUNC_ENTER_NOAPI(H5O_plist_size, 0);
 
     /* check args */
     assert(plist);
 
-    ret_value = 2 +                             /*version info          */
+    ret_value = 1 +                             /*version info          */
                 1;                              /*reserved              */
 
-    /*
-     * Loop through the class and its parent(s) to gather the complete
-     * length of the name. The class name encoded will look like:
-     *
-     *      DerivedClass/ParentClass/.../BaseClass
-     */
-    pclass = plist->pclass;
-
-    while (pclass) {
-        if (pclass->name)
-            ret_value += HDstrlen(pclass->name);/*length of class name  */
-
-        if ((pclass = pclass->parent) != NULL)
-            ++ret_value;                        /*separating "/"        */
-    }
-
-    ++ret_value;                                /*terminating NULL      */
-
     class_path = H5P_get_class_path(plist->pclass);
 
     if (class_path)
@@ -437,31 +413,29 @@ H5O_plist_size(H5F_t UNUSED *f, const void *mesg)
         ++ret_value;
 
     HDfree(class_path);
-    ret_value += sizeof(plist->nprops) +           /*num properties     */
-                 sizeof(plist->pclass->hashsize);  /*hash size          */
 
-    for (i = 0; i < plist->pclass->hashsize; ++i) {
-        H5P_genprop_t *tprop = plist->props[i];
+    ret_value += sizeof(plist->nprops);            /*num properties     */
 
-        /* Walk through the list of properties at each hash location */
-        while (tprop) {
-            const char *n = tprop->name;
+    /* Calculate the size of the properties for this property list */
+    if(plist->nprops>0) {
+        H5TB_NODE *curr_node;   /* Current node in TBBT */
+        H5P_genprop_t *tprop;   /* Pointer to property */
 
-            ret_value += sizeof(tprop->xor_val) + /*xored value         */
-                         sizeof(size_t);          /*length of the name  */
+        /* Walk through the properties in the old class */
+        curr_node=H5TB_first(plist->props->root);
+        while(curr_node!=NULL) {
+            /* Get a pointer to the property from the node */
+            tprop=curr_node->data;
 
-            if (n && *n)
-                ret_value += HDstrlen(n) + 1;   /*the name              */
-            else
-                ++ret_value;                    /*the name: NULL        */
+            ret_value += sizeof(size_t);            /*length of the name  */
+            ret_value += HDstrlen(tprop->name) + 1; /*the name              */
+            ret_value += sizeof(tprop->size) +      /*size of data size     */
+                         tprop->size;               /*the data              */
 
-            ret_value += sizeof(tprop->size) +  /*size of data size     */
-                         tprop->size;           /*the data              */
-
-            /* Go to next registered property in class */
-            tprop = tprop->next;
-        }
-    }
+            /* Get the next property node in the TBBT */
+            curr_node=H5TB_next(curr_node);
+        } /* end while */
+    } /* end if */
 
 done:
     FUNC_LEAVE(ret_value);
@@ -513,8 +487,7 @@ H5O_plist_debug(H5F_t UNUSED *f, const void *mesg, FILE *stream,
                 int indent, int fwidth)
 {
     const H5P_genplist_t *plist = (const H5P_genplist_t *)mesg;
-    herr_t ret_value = SUCCEED;
-    unsigned int i;
+    herr_t ret_value=SUCCEED;
 
     FUNC_ENTER_NOAPI(H5O_plist_debug, FAIL);
 
@@ -531,27 +504,30 @@ H5O_plist_debug(H5F_t UNUSED *f, const void *mesg, FILE *stream,
     HDfprintf(stream, "%*sProperties {\n", indent, "");
     indent += 2;
 
-    for (i = 0; i < plist->pclass->hashsize; ++i) {
-        H5P_genprop_t *tprop = plist->props[i];
+    /* Calculate the size of the properties for this property list */
+    if(plist->nprops>0) {
+        H5TB_NODE *curr_node;   /* Current node in TBBT */
+        H5P_genprop_t *tprop;   /* Pointer to property */
 
-        /* Walk through the list of properties at each hash location */
-        while (tprop) {
+        /* Walk through the properties in the old class */
+        curr_node=H5TB_first(plist->props->root);
+        while(curr_node!=NULL) {
             register unsigned int j;
 
+            /* Get a pointer to the property from the node */
+            tprop=curr_node->data;
+
             HDfprintf(stream, "%*sProperty {\n", indent, "");
             indent += 2;
 
             /*
-             * Copy the meat of the generic property:
+             * Print the meat of the generic property:
              *
              *      1. The name of the property
-             *      2. The XORed version of the name
-             *      3. The size of the property value
-             *      4. The property value
+             *      2. The size of the property value
+             *      3. The property value
              */
-            HDfprintf(stream, "%*sName: ", indent, "");
-            HDfprintf(stream, "%s\n", tprop->name ? tprop->name : "(null)");
-            HDfprintf(stream, "%*sXOR Value: %d\n", indent, "", tprop->xor_val);
+            HDfprintf(stream, "%*sName: %s\n", indent, "", tprop->name);
             HDfprintf(stream, "%*sValue Size: %d\n", indent, "", tprop->size);
             HDfprintf(stream, "%*sValue: ", indent, "");
 
@@ -561,10 +537,10 @@ H5O_plist_debug(H5F_t UNUSED *f, const void *mesg, FILE *stream,
             indent -= 2;
             HDfprintf(stream, "\n%*s}\n", indent, "");
 
-            /* Go to next registered property in class */
-            tprop = tprop->next;
-        }
-    }
+            /* Get the next property node in the TBBT */
+            curr_node=H5TB_next(curr_node);
+        } /* end while */
+    } /* end if */
 
     indent -= 2;
     HDfprintf(stream, "%*s}\n", indent, "");
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index 00b9e8f..651dbca 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -91,7 +91,7 @@ typedef struct H5O_class_t {
     herr_t	(*reset)(void *);		 /*free nested data structs  */
     herr_t	(*free)(void *);		 /*free main data struct  */
     herr_t	(*get_share)(H5F_t*, const void*, struct H5O_shared_t*);
-    herr_t  (*set_share)(H5F_t*, void*, const struct H5O_shared_t*);
+    herr_t	(*set_share)(H5F_t*, void*, const struct H5O_shared_t*);
     herr_t	(*debug)(H5F_t*, const void*, FILE*, int, int);
 } H5O_class_t;
 
@@ -116,14 +116,14 @@ typedef struct H5O_t {
     H5AC_info_t cache_info; /* Information for H5AC cache functions, _must_ be */
                             /* first field in structure */
     hbool_t	dirty;			/*out of data wrt disk		     */
-    int	version;		/*version number		     */
-    int	nlink;			/*link count			     */
+    int		version;		/*version number		     */
+    int		nlink;			/*link count			     */
     unsigned	nmesgs;			/*number of messages		     */
-    unsigned	alloc_nmesgs;	/*number of message slots	     */
-    H5O_mesg_t	*mesg;		/*array of messages		     */
+    unsigned	alloc_nmesgs;		/*number of message slots	     */
+    H5O_mesg_t	*mesg;			/*array of messages		     */
     unsigned	nchunks;		/*number of chunks		     */
-    unsigned	alloc_nchunks;	/*chunks allocated		     */
-    H5O_chunk_t *chunk;		/*array of chunks		     */
+    unsigned	alloc_nchunks;		/*chunks allocated		     */
+    H5O_chunk_t *chunk;			/*array of chunks		     */
 } H5O_t;
 
 /*
@@ -194,9 +194,9 @@ typedef struct H5O_efl_entry_t {
 
 typedef struct H5O_efl_t {
     haddr_t	heap_addr;		/*address of name heap		     */
-    int	nalloc;			/*number of slots allocated	     */
-    int	nused;			/*number of slots used		     */
-    H5O_efl_entry_t *slot;	/*array of external file entries     */
+    int	nalloc;				/*number of slots allocated	     */
+    int	nused;				/*number of slots used		     */
+    H5O_efl_entry_t *slot;		/*array of external file entries     */
 } H5O_efl_t;
 
 /*
@@ -227,10 +227,10 @@ typedef struct H5O_pline_t {
     size_t	nalloc;			/*num elements in `filter' array     */
     struct {
         H5Z_filter_t	id;		/*filter identification number	     */
-        unsigned		flags;		/*defn and invocation flags	     */
+        unsigned	flags;		/*defn and invocation flags	     */
         char		*name;		/*optional filter name		     */
         size_t		cd_nelmts;	/*number of elements in cd_values[]  */
-        unsigned		*cd_values;	/*client data values		     */
+        unsigned	*cd_values;	/*client data values		     */
     } *filter;				/*array of filters		     */
 } H5O_pline_t;
 
@@ -303,9 +303,15 @@ typedef struct H5O_stab_t {
 } H5O_stab_t;
 
 /*
+ * Modification time message (new format on disk).  The message is just a `time_t'.
+ */
+#define H5O_MTIME_NEW_ID	0x0012
+H5_DLLVAR const H5O_class_t H5O_MTIME_NEW[1];
+
+/*
  * Generic property list message.
  */
-#define H5O_PLIST_ID	0x0012
+#define H5O_PLIST_ID	0x0013
 H5_DLLVAR const H5O_class_t H5O_PLIST[1];
 
 /* operates on an H5P_genplist_t struct */
@@ -314,7 +320,7 @@ H5_DLLVAR const H5O_class_t H5O_PLIST[1];
 /*
  * Flexible parallel message
  */
-#define H5O_FPHDF5_ID	0x0013
+#define H5O_FPHDF5_ID	0x0014
 H5_DLLVAR const H5O_class_t H5O_FPHDF5[1];
 
 struct H5S_simple_t;
@@ -349,8 +355,13 @@ H5_DLL htri_t H5O_exists(H5G_entry_t *ent, const H5O_class_t *type,
 H5_DLL void *H5O_read(H5G_entry_t *ent, const H5O_class_t *type,
 		       int sequence, void *mesg);
 H5_DLL int H5O_modify(H5G_entry_t *ent, const H5O_class_t *type,
-			int overwrite, unsigned flags, const void *mesg);
+    int overwrite, unsigned flags, unsigned update_time, const void *mesg);
+H5_DLL H5O_t * H5O_protect(H5G_entry_t *ent);
+H5_DLL herr_t H5O_unprotect(H5G_entry_t *ent, H5O_t *oh);
+H5_DLL int H5O_append(H5F_t *f, H5O_t *oh, const H5O_class_t *type, 
+    unsigned flags, const void *mesg);
 H5_DLL herr_t H5O_touch(H5G_entry_t *ent, hbool_t force);
+H5_DLL herr_t H5O_touch_oh(H5F_t *f, H5O_t *oh, hbool_t force);
 H5_DLL herr_t H5O_remove(H5G_entry_t *ent, const H5O_class_t *type,
 			  int sequence);
 H5_DLL herr_t H5O_reset(const H5O_class_t *type, void *native);
diff --git a/src/H5Osdspace.c b/src/H5Osdspace.c
index 1ff3a18..6114e51 100644
--- a/src/H5Osdspace.c
+++ b/src/H5Osdspace.c
@@ -44,7 +44,7 @@ const H5O_class_t H5O_SDSPACE[1] = {{
     H5O_sdspace_copy,	    	/* copy the native value		*/
     H5O_sdspace_size,	    	/* size of symbol table entry	    	*/
     H5O_sdspace_reset,	    	/* default reset method		    	*/
-    H5O_sdspace_free,		    /* free method			*/
+    H5O_sdspace_free,		/* free method				*/
     NULL,		    	/* get share method			*/
     NULL, 			/* set share method			*/
     H5O_sdspace_debug,	        /* debug the message		    	*/
@@ -105,7 +105,7 @@ H5O_sdspace_decode(H5F_t *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
     assert (!sh);
 
     /* decode */
-    if ((sdim = H5FL_ALLOC(H5S_simple_t,1)) != NULL) {
+    if ((sdim = H5FL_CALLOC(H5S_simple_t)) != NULL) {
         version = *p++;
         if (version!=H5O_SDSPACE_VERSION)
             HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, NULL, "wrong version number in data space message");
@@ -116,19 +116,19 @@ H5O_sdspace_decode(H5F_t *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
         p += 5; /*reserved*/
 
         if (sdim->rank > 0) {
-            if (NULL==(sdim->size=H5FL_ARR_ALLOC(hsize_t,sdim->rank,0)))
+            if (NULL==(sdim->size=H5FL_ARR_MALLOC(hsize_t,sdim->rank)))
                 HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
             for (u = 0; u < sdim->rank; u++)
                 H5F_DECODE_LENGTH (f, p, sdim->size[u]);
             if (flags & H5S_VALID_MAX) {
-                if (NULL==(sdim->max=H5FL_ARR_ALLOC(hsize_t,sdim->rank,0)))
+                if (NULL==(sdim->max=H5FL_ARR_MALLOC(hsize_t,sdim->rank)))
                     HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
                 for (u = 0; u < sdim->rank; u++)
                     H5F_DECODE_LENGTH (f, p, sdim->max[u]);
             }
 #ifdef LATER
             if (flags & H5S_VALID_PERM) {
-                if (NULL==(sdim->perm=H5FL_ARR_ALLOC(hsize_t,sdim->rank,0)))
+                if (NULL==(sdim->perm=H5FL_ARR_MALLOC(hsize_t,sdim->rank)))
                     HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
                 for (u = 0; u < sdim->rank; u++)
                     UINT32DECODE(p, sdim->perm[u]);
@@ -254,25 +254,25 @@ H5O_sdspace_copy(const void *mesg, void *dest)
 
     /* check args */
     assert(src);
-    if (!dst && NULL==(dst = H5FL_ALLOC(H5S_simple_t,0)))
+    if (!dst && NULL==(dst = H5FL_MALLOC(H5S_simple_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* deep copy -- pointed-to values are copied also */
     HDmemcpy(dst, src, sizeof(H5S_simple_t));
     
     if (src->size) {
-	if (NULL==(dst->size = H5FL_ARR_ALLOC(hsize_t,src->rank,0)))
+	if (NULL==(dst->size = H5FL_ARR_MALLOC(hsize_t,src->rank)))
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 	HDmemcpy (dst->size, src->size, src->rank*sizeof(src->size[0]));
     }
     if (src->max) {
-	if (NULL==(dst->max=H5FL_ARR_ALLOC(hsize_t,src->rank,0)))
+	if (NULL==(dst->max=H5FL_ARR_MALLOC(hsize_t,src->rank)))
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 	HDmemcpy (dst->max, src->max, src->rank*sizeof(src->max[0]));
     }
 #ifdef LATER
     if (src->perm) {
-	if (NULL==(dst->perm=H5FL_ARR_ALLOC(hsize_t,src->rank,0)))
+	if (NULL==(dst->perm=H5FL_ARR_MALLOC(hsize_t,src->rank)))
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 	HDmemcpy (dst->perm, src->perm, src->rank*sizeof(src->perm[0]));
     }
diff --git a/src/H5Ostab.c b/src/H5Ostab.c
index 1675c51..182f280 100644
--- a/src/H5Ostab.c
+++ b/src/H5Ostab.c
@@ -88,7 +88,7 @@ H5O_stab_decode(H5F_t *f, const uint8_t *p, H5O_shared_t UNUSED *sh)
     assert (!sh);
 
     /* decode */
-    if (NULL==(stab = H5FL_ALLOC(H5O_stab_t,1)))
+    if (NULL==(stab = H5FL_CALLOC(H5O_stab_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     H5F_addr_decode(f, &p, &(stab->btree_addr));
     H5F_addr_decode(f, &p, &(stab->heap_addr));
@@ -177,7 +177,7 @@ H5O_stab_fast(const H5G_cache_t *cache, const H5O_class_t *type, void *_mesg)
     if (H5O_STAB == type) {
         if (_mesg) {
 	    stab = (H5O_stab_t *) _mesg;
-        } else if (NULL==(stab = H5FL_ALLOC(H5O_stab_t,1))) {
+        } else if (NULL==(stab = H5FL_CALLOC(H5O_stab_t))) {
 	    HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 	}
         stab->btree_addr = cache->stab.btree_addr;
@@ -221,7 +221,7 @@ H5O_stab_copy(const void *_mesg, void *_dest)
 
     /* check args */
     assert(stab);
-    if (!dest && NULL==(dest = H5FL_ALLOC(H5O_stab_t,1)))
+    if (!dest && NULL==(dest = H5FL_MALLOC(H5O_stab_t)))
 	HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     
     /* copy */
diff --git a/src/H5P.c b/src/H5P.c
index 7913b78..a7341cb 100644
--- a/src/H5P.c
+++ b/src/H5P.c
@@ -21,7 +21,8 @@
 #include "H5private.h"		/* Generic Functions			*/
 #include "H5Dprivate.h"		/* Datasets				*/
 #include "H5Eprivate.h"		/* Error handling		  	*/
-#include "H5Fprivate.h"		/* Files		  	*/
+#include "H5Fprivate.h"		/* Files		  	        */
+#include "H5FLprivate.h"	/* Free lists                           */
 #include "H5Iprivate.h"		/* IDs			  		*/
 #include "H5MMprivate.h"	/* Memory management			*/
 #include "H5Ppkg.h"		/* Property lists		  	*/
@@ -34,6 +35,8 @@ static int		interface_initialize_g = 0;
 #define INTERFACE_INIT H5P_init_interface
 static herr_t		H5P_init_interface(void);
 
+/* Local variables */
+
 /*
  * Predefined property list classes. These are initialized at runtime by 
  * H5P_init_interface() in this source file.
@@ -56,6 +59,19 @@ hid_t H5P_LST_DATASET_CREATE_g      = FAIL;
 hid_t H5P_LST_DATASET_XFER_g        = FAIL;
 hid_t H5P_LST_MOUNT_g               = FAIL;
 
+/* Track the revision count of a class, to make comparisons faster */
+static unsigned H5P_next_rev=0;
+#define H5P_GET_NEXT_REV        (H5P_next_rev++)
+
+/* Declare a free list to manage the H5P_genprop_t struct */
+H5FL_DEFINE(H5P_genprop_t);
+
+/* Declare a free list to manage the H5P_genplist_t struct */
+H5FL_DEFINE(H5P_genplist_t);
+
+/* Declare a free list to manage the H5P_genclass_t struct */
+H5FL_DEFINE_STATIC(H5P_genclass_t);
+
 /* Local typedefs */
 
 /* Typedef for checking for duplicate class names in parent class */
@@ -66,15 +82,84 @@ typedef struct {
 
 /* Local static functions */
 static H5P_genclass_t *H5P_create_class(H5P_genclass_t *par_class,
-     const char *name, unsigned hashsize, unsigned internal,
+     const char *name, unsigned internal,
      H5P_cls_create_func_t cls_create, void *create_data,
      H5P_cls_copy_func_t cls_copy, void *copy_data,
      H5P_cls_close_func_t cls_close, void *close_data);
 static herr_t H5P_unregister(H5P_genclass_t *pclass, const char *name);
-static H5P_genprop_t *H5P_dup_prop(H5P_genprop_t *oprop);
+static H5P_genprop_t *H5P_dup_prop(H5P_genprop_t *oprop, H5P_prop_within_t type);
 static herr_t H5P_free_prop(H5P_genprop_t *prop);
 
 
+/*--------------------------------------------------------------------------
+ NAME
+    H5P_do_prop_cb1
+ PURPOSE
+    Internal routine to call a property list callback routine and update
+    the property list accordingly.
+ USAGE
+    herr_t H5P_do_prop_cb1(tree,prop,cb)
+        H5TB_TREE *tree;        IN/OUT: TBBT to hold changed properties
+        H5P_genprop_t *prop;    IN: Property to call callback for
+        H5P_prp_cb1_t *cb;      IN: Callback routine to call
+ RETURNS
+    Returns non-negative on success, negative on failure.
+ DESCRIPTION
+        Calls the callback routine passed in.  If the callback routine changes
+    the property value, then the property is duplicated and added to TBBT.
+
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+static herr_t
+H5P_do_prop_cb1(H5TB_TREE *tree, H5P_genprop_t *prop, H5P_prp_cb1_t cb)
+{
+    void *tmp_value=NULL;       /* Temporary value buffer */
+    H5P_genprop_t *pcopy=NULL;  /* Copy of property to insert into TBBT */
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOINIT(H5P_do_prop_cb1);
+
+    /* Allocate space for a temporary copy of the property value */
+    if (NULL==(tmp_value=H5MM_malloc(prop->size)))
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for temporary property value");
+    HDmemcpy(tmp_value,prop->value,prop->size);
+
+    /* Call "type 1" callback ('create', 'copy' or 'close') */
+    if(cb(prop->name,prop->size,tmp_value)<0)
+        HGOTO_ERROR (H5E_PLIST, H5E_CANTINIT, NULL,"Property callback failed");
+
+    /* Check if the property value changed */
+    if(HDmemcmp(tmp_value,prop->value,prop->size)) {
+        /* Make a copy of the class's property */
+        if((pcopy=H5P_dup_prop(prop,H5P_PROP_WITHIN_LIST))==NULL)
+            HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, NULL,"Can't copy property");
+
+        /* Copy the changed value into the new property */
+        HDmemcpy(pcopy->value,tmp_value,prop->size);
+
+        /* Insert the changed property into the property list */
+        if(H5P_add_prop(tree,pcopy)<0)
+            HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, NULL,"Can't insert property into TBBT");
+    } /* end if */
+
+done:
+    /* Release the temporary value buffer */
+    if(tmp_value!=NULL)
+        H5MM_xfree(tmp_value);
+
+    /* Cleanup on failure */
+    if(ret_value<0) {
+        if(pcopy!=NULL)
+            H5P_free_prop(pcopy);
+    } /* end if */
+
+    FUNC_LEAVE(ret_value);
+} /* end H5P_do_prop_cb1() */
+
+
 /*-------------------------------------------------------------------------
  * Function:	H5P_init
  *
@@ -106,60 +191,6 @@ done:
 
 /*--------------------------------------------------------------------------
 NAME
-    H5P_xor_name -- Generate an xor'ed value for a string
-USAGE
-    unsigned H5P_xor_name(s)
-        const char *s;  IN: String to operate over
-RETURNS
-    Always returns valid value
-DESCRIPTION
-    Generates an xor'ed value for a string
---------------------------------------------------------------------------*/
-static unsigned
-H5P_xor_name(const char *s)
-{
-    unsigned ret=0;
-    unsigned char temp;
-
-    /* Use FUNC_ENTER_NOINIT here to avoid performance issues */
-    FUNC_ENTER_NOINIT(H5P_xor_name);
-
-    if(s!=NULL)
-        while(*s!='\0') {
-            temp=(ret>>24)&0xff;
-            ret <<= 8;
-            ret |= temp;
-            ret ^= *s++;
-        }
-
-    FUNC_LEAVE(ret);
-}   /* end H5P_xor_name() */
-
-
-/*--------------------------------------------------------------------------
-NAME
-    H5P_hash_name -- Generate a hash value for a string
-USAGE
-    unsigned H5P_hash_name(s, hashsize)
-        const char *s;  IN: String to operate over
-        unsigned;          IN: Size of hash table to clip against
-RETURNS
-    Always returns valid value
-DESCRIPTION
-    Generates a hash location based on an xor'ed value for a string
---------------------------------------------------------------------------*/
-static unsigned
-H5P_hash_name(const char *s, unsigned hashsize)
-{
-    /* Use FUNC_ENTER_NOINIT here to avoid performance issues */
-    FUNC_ENTER_NOINIT(H5P_hash_name);
-
-    FUNC_LEAVE(H5P_xor_name(s)%hashsize);
-}   /* end H5P_hash_name() */
-
-
-/*--------------------------------------------------------------------------
-NAME
    H5P_init_interface -- Initialize interface-specific information
 USAGE
     herr_t H5P_init_interface()
@@ -195,7 +226,7 @@ H5P_init_interface(void)
 
     /* Allocate the root class */
     assert(H5P_CLS_NO_CLASS_g==(-1));
-    if (NULL==(root_class = H5P_create_class (NULL,"root",H5P_NO_CLASS_HASH_SIZE,1,NULL,NULL,NULL,NULL,NULL,NULL)))
+    if (NULL==(root_class = H5P_create_class (NULL,"root",1,NULL,NULL,NULL,NULL,NULL,NULL)))
         HGOTO_ERROR (H5E_PLIST, H5E_CANTINIT, FAIL, "class initialization failed");
 
     /* Register the root class */
@@ -206,7 +237,7 @@ H5P_init_interface(void)
 
     /* Allocate the file creation class */
     assert(H5P_CLS_FILE_CREATE_g==(-1));
-    if (NULL==(pclass = H5P_create_class (root_class,"file create",H5P_FILE_CREATE_HASH_SIZE,1,NULL,NULL,NULL,NULL,NULL,NULL)))
+    if (NULL==(pclass = H5P_create_class (root_class,"file create",1,NULL,NULL,NULL,NULL,NULL,NULL)))
         HGOTO_ERROR (H5E_PLIST, H5E_CANTINIT, FAIL, "class initialization failed");
 
     /* Register the file creation class */
@@ -215,7 +246,7 @@ H5P_init_interface(void)
 
     /* Allocate the file access class */
     assert(H5P_CLS_FILE_ACCESS_g==(-1));
-    if (NULL==(pclass = H5P_create_class (root_class,"file access",H5P_FILE_ACCESS_HASH_SIZE,1,H5F_acs_create,NULL,H5F_acs_copy,NULL,H5F_acs_close,NULL)))
+    if (NULL==(pclass = H5P_create_class (root_class,"file access",1,H5F_acs_create,NULL,H5F_acs_copy,NULL,H5F_acs_close,NULL)))
         HGOTO_ERROR (H5E_PLIST, H5E_CANTINIT, FAIL, "class initialization failed");
 
     /* Register the file access class */
@@ -226,7 +257,7 @@ H5P_init_interface(void)
 
     /* Allocate the dataset creation class */
     assert(H5P_CLS_DATASET_CREATE_g==(-1));
-    if (NULL==(pclass = H5P_create_class (root_class,"dataset create",H5P_DATASET_CREATE_HASH_SIZE,1,NULL,NULL,H5D_crt_copy,NULL,H5D_crt_close,NULL)))
+    if (NULL==(pclass = H5P_create_class (root_class,"dataset create",1,NULL,NULL,H5D_crt_copy,NULL,H5D_crt_close,NULL)))
         HGOTO_ERROR (H5E_PLIST, H5E_CANTINIT, FAIL, "class initialization failed");
 
     /* Register the dataset creation class */
@@ -235,7 +266,7 @@ H5P_init_interface(void)
 
     /* Allocate the data xfer class */
     assert(H5P_CLS_DATASET_XFER_g==(-1));
-    if (NULL==(pclass = H5P_create_class (root_class,"data xfer",H5P_DATASET_XFER_HASH_SIZE,1,H5D_xfer_create,NULL,H5D_xfer_copy,NULL,H5D_xfer_close,NULL)))
+    if (NULL==(pclass = H5P_create_class (root_class,"data xfer",1,H5D_xfer_create,NULL,H5D_xfer_copy,NULL,H5D_xfer_close,NULL)))
         HGOTO_ERROR (H5E_PLIST, H5E_CANTINIT, FAIL, "class initialization failed");
 
     /* Register the data xfer class */
@@ -244,7 +275,7 @@ H5P_init_interface(void)
 
     /* Allocate the mount class */
     assert(H5P_CLS_MOUNT_g==(-1));
-    if (NULL==(pclass = H5P_create_class (root_class,"file mount",H5P_MOUNT_HASH_SIZE,1,NULL,NULL,NULL,NULL,NULL,NULL)))
+    if (NULL==(pclass = H5P_create_class (root_class,"file mount",1,NULL,NULL,NULL,NULL,NULL,NULL)))
         HGOTO_ERROR (H5E_PLIST, H5E_CANTINIT, FAIL, "class initialization failed");
 
     /* Register the mount class */
@@ -357,10 +388,8 @@ H5P_term_interface(void)
 static H5P_genclass_t *
 H5P_copy_pclass(H5P_genclass_t *pclass)
 {
-    H5P_genclass_t *new_pclass = NULL;      /* Property list class copied */
-    H5P_genprop_t *tmp;         /* Temporary pointer to parent class properties */
-    H5P_genprop_t *pcopy;       /* Copy of property to insert into class */
-    unsigned u;                 /* Local index variable */
+    H5P_genclass_t *new_pclass = NULL;  /* Property list class copied */
+    H5P_genprop_t *pcopy;               /* Copy of property to insert into class */
     H5P_genclass_t *ret_value=NULL;     /* return value */
 
     FUNC_ENTER_NOINIT(H5P_copy_pclass);
@@ -372,32 +401,30 @@ H5P_copy_pclass(H5P_genclass_t *pclass)
      */
 
     /* Create the new property list class */
-    if (NULL==(new_pclass=H5P_create_class(pclass->parent, pclass->name, pclass->hashsize, 0, pclass->create_func, pclass->create_data, pclass->copy_func, pclass->copy_data, pclass->close_func, pclass->close_data)))
+    if (NULL==(new_pclass=H5P_create_class(pclass->parent, pclass->name, 0, pclass->create_func, pclass->create_data, pclass->copy_func, pclass->copy_data, pclass->close_func, pclass->close_data)))
         HGOTO_ERROR(H5E_PLIST, H5E_CANTCREATE, NULL, "unable to create property list class");
 
     /* Copy the properties registered for this class */
     if(pclass->nprops>0) {
-        /* Walk through the hash table */
-        for(u=0; u<pclass->hashsize; u++) {
-            tmp=pclass->props[u];
+        H5TB_NODE *curr_node;   /* Current node in TBBT */
 
-            /* Walk through the list of properties at each hash location */
-            while(tmp!=NULL) {
-                /* Make a copy of the class's property */
-                if((pcopy=H5P_dup_prop(tmp))==NULL)
-                    HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, NULL,"Can't copy property");
+        /* Walk through the properties in the old class */
+        curr_node=H5TB_first(pclass->props->root);
+        while(curr_node!=NULL) {
+            /* Make a copy of the class's property */
+            if((pcopy=H5P_dup_prop(curr_node->data,H5P_PROP_WITHIN_CLASS))==NULL)
+                HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, NULL,"Can't copy property");
 
-                /* Insert the initialized property into the property list */
-                if(H5P_add_prop(new_pclass->props,new_pclass->hashsize,pcopy)<0)
-                    HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, NULL,"Can't insert property into class");
+            /* Insert the initialized property into the property list */
+            if(H5P_add_prop(new_pclass->props,pcopy)<0)
+                HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, NULL,"Can't insert property into class");
 
-                /* Increment property count for class */
-                new_pclass->nprops++;
+            /* Increment property count for class */
+            new_pclass->nprops++;
 
-                /* Go to next registered property in class */
-                tmp=tmp->next;
-            } /* end while */
-        } /* end for */
+            /* Get the next property node in the TBBT */
+            curr_node=H5TB_next(curr_node);
+        } /* end while */
     } /* end if */
 
     /* Set the return value */
@@ -432,13 +459,16 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-hid_t H5P_copy_plist(H5P_genplist_t *old_plist)
+hid_t
+H5P_copy_plist(H5P_genplist_t *old_plist)
 {
+    H5P_genclass_t *tclass;     /* Temporary class pointer */
     H5P_genplist_t *new_plist=NULL;  /* New property list generated from copy */
-    H5P_genprop_t *tprop;       /* Temporary pointer to properties */
+    H5P_genprop_t *tmp;         /* Temporary pointer to properties */
     H5P_genprop_t *new_prop;    /* New property created for copy */
     hid_t new_plist_id;         /* Property list ID of new list created */
-    unsigned u;                 /* Local index variable */
+    H5TB_NODE *curr_node;       /* Current node in TBBT */
+    H5TB_TREE *seen=NULL;       /* TBBT containing properties already seen */
     hid_t ret_value=FAIL;       /* return value */
  
     FUNC_ENTER_NOAPI(H5P_copy_plist, FAIL);
@@ -449,8 +479,8 @@ hid_t H5P_copy_plist(H5P_genplist_t *old_plist)
      * Create new property list object
      */
 
-    /* Allocate room for the property list & it's hash table of properties */
-    if (NULL==(new_plist = H5MM_calloc (sizeof(H5P_genplist_t)+((old_plist->pclass->hashsize-1)*sizeof(H5P_genprop_t *)))))
+    /* Allocate room for the property list */
+    if (NULL==(new_plist = H5FL_CALLOC(H5P_genplist_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL,"memory allocation failed");
 
     /* Set class state */
@@ -458,14 +488,54 @@ hid_t H5P_copy_plist(H5P_genplist_t *old_plist)
     new_plist->nprops = 0;      /* Initially the plist has the same number of properties as the class */
     new_plist->class_init = 0;  /* Initially, wait until the class callback finishes to set */
 
+    /* Initialize the TBBT to hold the changed properties */
+    if((new_plist->props=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,FAIL,"can't create TBBT for changed properties");
+
+    /* Create the TBBT for deleted properties */
+    if((new_plist->del=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,NULL,"can't create TBBT for deleted properties");
+
+    /* Create the TBBT to hold names of properties already seen
+     * (This prevents a property in the class hierarchy from having it's
+     * 'create' callback called, if a property in the class hierarchy has
+     * already been seen)
+     */
+    if((seen=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,NULL,"can't create TBBT for seen properties");
+
+    /* Cycle through the deleted properties & copy them into the new list's deleted section */
+    if(old_plist->del->root) {
+        curr_node=H5TB_first(old_plist->del->root);
+        while(curr_node) {
+            char *new_name;   /* Pointer to new name */
+
+            /* Duplicate string for insertion into new deleted property TBBT */
+            if((new_name=H5MM_xstrdup(curr_node->data))==NULL)
+                HGOTO_ERROR(H5E_RESOURCE,H5E_NOSPACE,FAIL,"memory allocation failed");
+
+            /* Insert property name into deleted list */
+            if(H5TB_dins(new_plist->del,new_name,new_name)==NULL)
+                HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,NULL,"can't insert property into deleted TBBT");
+
+            /* Add property name to "seen" list */
+            if(H5TB_dins(seen,new_name,new_name)==NULL)
+                HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,NULL,"can't insert property into seen TBBT");
+
+            /* Get the next property node in the TBBT */
+            curr_node=H5TB_next(curr_node);
+        } /* end while */
+    } /* end if */
+
     /* Cycle through the properties and copy them also */
-    for(u=0; u<old_plist->pclass->hashsize; u++) {
-        tprop=old_plist->props[u];
+    if(old_plist->props->root) {
+        curr_node=H5TB_first(old_plist->props->root);
+        while(curr_node) {
+            /* Get a pointer to the node's property */
+            tmp=curr_node->data;
 
-        /* Walk through the list of properties at each hash location */
-        while(tprop!=NULL) {
             /* Make a copy of the list's property */
-            if((new_prop=H5P_dup_prop(tprop))==NULL)
+            if((new_prop=H5P_dup_prop(tmp,H5P_PROP_WITHIN_LIST))==NULL)
                 HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, FAIL,"Can't copy property");
 
             /* Call property copy callback, if it exists */
@@ -477,16 +547,61 @@ hid_t H5P_copy_plist(H5P_genplist_t *old_plist)
             } /* end if */
 
             /* Insert the initialized property into the property list */
-            if(H5P_add_prop(new_plist->props,new_plist->pclass->hashsize,new_prop)<0)
+            if(H5P_add_prop(new_plist->props,new_prop)<0) {
+                H5P_free_prop(new_prop);
                 HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, FAIL,"Can't insert property into list");
+            } /* end if */
+
+            /* Add property name to "seen" list */
+            if(H5TB_dins(seen,new_prop->name,new_prop->name)==NULL)
+                HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,NULL,"can't insert property into seen TBBT");
 
             /* Increment the number of properties in list */
             new_plist->nprops++;
 
-            /* Go to next registered property in class */
-            tprop=tprop->next;
+            /* Get the next property node in the TBBT */
+            curr_node=H5TB_next(curr_node);
         } /* end while */
-    } /* end for */
+    } /* end if */
+
+    /*
+     * Check for copying class properties (up through list of parent classes also),
+     * initialize each with default value & make property 'copy' callback.
+     */
+    tclass=old_plist->pclass;
+    while(tclass!=NULL) {
+        if(tclass->nprops>0) {
+            /* Walk through the properties in the old class */
+            curr_node=H5TB_first(tclass->props->root);
+            while(curr_node!=NULL) {
+                /* Get pointer to property from node */
+                tmp=curr_node->data;
+
+                /* Only "copy" properties we haven't seen before */
+                if(H5TB_dfind(seen,tmp->name,NULL)==NULL) {
+                    /* Call property creation callback, if it exists */
+                    if(tmp->copy) {
+                        /* Call the callback & insert changed value into tree (if necessary) */
+                        if(H5P_do_prop_cb1(new_plist->props,tmp,tmp->copy)<0)
+                            HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, NULL,"Can't create property");
+                    } /* end if */
+
+                    /* Add property name to "seen" list */
+                    if(H5TB_dins(seen,tmp->name,tmp->name)==NULL)
+                        HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,NULL,"can't insert property into seen TBBT");
+
+                    /* Increment the number of properties in list */
+                    new_plist->nprops++;
+                } /* end if */
+
+                /* Get the next property node in the TBBT */
+                curr_node=H5TB_next(curr_node);
+            } /* end while */
+        } /* end if */
+
+        /* Go up to parent class */
+        tclass=tclass->parent;
+    } /* end while */
 
     /* Increment the number of property lists derived from class */
     if(H5P_access_class(new_plist->pclass,H5P_MOD_INC_LST)<0)
@@ -515,6 +630,10 @@ hid_t H5P_copy_plist(H5P_genplist_t *old_plist)
     ret_value=new_plist_id;
 
 done:
+    /* Release the tree of 'seen' properties */
+    if(seen!=NULL)
+        H5TB_dfree(seen,NULL,NULL);
+
     if (ret_value<0 && new_plist)
         H5P_close(new_plist);
 
@@ -543,7 +662,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-hid_t H5Pcopy(hid_t id)
+hid_t
+H5Pcopy(hid_t id)
 {
     void *obj;                 /* Property object to copy */
     hid_t ret_value=FALSE;      /* return value */
@@ -592,6 +712,7 @@ done:
  USAGE
     H5P_genprop_t *H5P_dup_prop(oprop)
         H5P_genprop_t *oprop;   IN: Pointer to property to copy
+        H5P_prop_within_t type; IN: Type of object the property will be inserted into
  RETURNS
     Returns a pointer to the newly created duplicate of a property on success,
         NULL on failure.
@@ -603,7 +724,7 @@ done:
  REVISION LOG
 --------------------------------------------------------------------------*/
 static H5P_genprop_t *
-H5P_dup_prop(H5P_genprop_t *oprop)
+H5P_dup_prop(H5P_genprop_t *oprop, H5P_prop_within_t type)
 {
     H5P_genprop_t *prop=NULL;        /* Pointer to new property copied */
     H5P_genprop_t *ret_value;        /* Return value */
@@ -611,16 +732,47 @@ H5P_dup_prop(H5P_genprop_t *oprop)
     FUNC_ENTER_NOINIT(H5P_dup_prop);
 
     assert(oprop);
+    assert(type!=H5P_PROP_WITHIN_UNKNOWN);
 
     /* Allocate the new property */
-    if (NULL==(prop = H5MM_malloc (sizeof(H5P_genprop_t))))
+    if (NULL==(prop = H5FL_MALLOC (H5P_genprop_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* Copy basic property information */
     HDmemcpy(prop,oprop,sizeof(H5P_genprop_t));
 
-    /* Duplicate name */
-    prop->name = H5MM_xstrdup(oprop->name);
+    /* Check if we should duplicate the name or share it */
+
+    /* Duplicating property for a class */
+    if(type==H5P_PROP_WITHIN_CLASS) {
+        assert(oprop->type==H5P_PROP_WITHIN_CLASS);
+        assert(oprop->shared_name==0);
+
+        /* Duplicate name */
+        prop->name = H5MM_xstrdup(oprop->name);
+    } /* end if */
+    /* Duplicating property for a list */
+    else {
+        /* Check if we are duplicating a property from a list or a class */
+
+        /* Duplicating a property from a list */
+        if(oprop->type==H5P_PROP_WITHIN_LIST) {
+            /* If the old property's name wasn't shared, we have to copy it here also */
+            if(!oprop->shared_name)
+                prop->name = H5MM_xstrdup(oprop->name);
+        } /* end if */
+        /* Duplicating a property from a class */
+        else {
+            assert(oprop->type==H5P_PROP_WITHIN_CLASS);
+            assert(oprop->shared_name==0);
+
+            /* Share the name */
+            prop->shared_name=1;
+
+            /* Set the type */
+            prop->type=type;
+        } /* end else */
+    } /* end else */
 
     /* Duplicate current value, if it exists */
     if(oprop->value!=NULL) {
@@ -630,17 +782,6 @@ H5P_dup_prop(H5P_genprop_t *oprop)
         HDmemcpy(prop->value,oprop->value,prop->size);
     } /* end if */
 
-    /* Duplicate default value, if it exists */
-    if(oprop->def_value!=NULL) {
-        assert(prop->size>0);
-        if (NULL==(prop->def_value = H5MM_malloc (prop->size)))
-            HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-        HDmemcpy(prop->def_value,oprop->def_value,prop->size);
-    } /* end if */
-
-    /* Reset the link to the next property */
-    prop->next=NULL;
-
     /* Set return value */
     ret_value=prop;
 
@@ -652,9 +793,7 @@ done:
                 H5MM_xfree(prop->name);
             if(prop->value!=NULL)
                 H5MM_xfree(prop->value);
-            if(prop->def_value!=NULL)
-                H5MM_xfree(prop->def_value);
-            H5MM_xfree(prop);
+            H5FL_FREE(H5P_genprop_t,prop);
         } /* end if */
     } /* end if */
 
@@ -668,12 +807,12 @@ done:
  PURPOSE
     Internal routine to create a new property
  USAGE
-    H5P_genprop_t *H5P_create_prop(name,size,def_value,prp_create,prp_set,
+    H5P_genprop_t *H5P_create_prop(name,size,type,value,prp_create,prp_set,
             prp_get,prp_delete,prp_close)
         const char *name;       IN: Name of property to register
         size_t size;            IN: Size of property in bytes
-        void *def_value;        IN: Pointer to buffer containing default value
-                                    for property in newly created property lists
+        H5P_prop_within_t type; IN: Type of object the property will be inserted into
+        void *value;            IN: Pointer to buffer containing value for property
         H5P_prp_create_func_t prp_create;   IN: Function pointer to property
                                     creation callback
         H5P_prp_set_func_t prp_set; IN: Function pointer to property set callback
@@ -693,7 +832,8 @@ done:
  REVISION LOG
 --------------------------------------------------------------------------*/
 static H5P_genprop_t *
-H5P_create_prop(const char *name, size_t size, void *def_value, void *value,
+H5P_create_prop(const char *name, size_t size, H5P_prop_within_t type,
+    void *value,
     H5P_prp_create_func_t prp_create, H5P_prp_set_func_t prp_set,
     H5P_prp_get_func_t prp_get, H5P_prp_delete_func_t prp_delete,
     H5P_prp_copy_func_t prp_copy, H5P_prp_close_func_t prp_close)
@@ -704,16 +844,18 @@ H5P_create_prop(const char *name, size_t size, void *def_value, void *value,
     FUNC_ENTER_NOINIT(H5P_create_prop);
 
     assert(name);
-    assert((size>0 && (def_value!=NULL || value!=NULL)) || (size==0));
+    assert((size>0 && value!=NULL) || (size==0));
+    assert(type!=H5P_PROP_WITHIN_UNKNOWN);
 
     /* Allocate the new property */
-    if (NULL==(prop = H5MM_malloc (sizeof(H5P_genprop_t))))
+    if (NULL==(prop = H5FL_MALLOC (H5P_genprop_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* Set the property initial values */
-    prop->xor_val = H5P_xor_name(name); /* Generate the XOR'd value for the name */
     prop->name = H5MM_xstrdup(name); /* Duplicate name */
+    prop->shared_name=0;
     prop->size=size;
+    prop->type=type;
 
     /* Duplicate value, if it exists */
     if(value!=NULL) {
@@ -724,15 +866,6 @@ H5P_create_prop(const char *name, size_t size, void *def_value, void *value,
     else
         prop->value=NULL;
 
-    /* Duplicate default value, if it exists */
-    if(def_value!=NULL) {
-        if (NULL==(prop->def_value = H5MM_malloc (prop->size)))
-            HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-        HDmemcpy(prop->def_value,def_value,prop->size);
-    } /* end if */
-    else
-        prop->def_value=NULL;
-
     /* Set the function pointers */
     prop->create=prp_create;
     prop->set=prp_set;
@@ -741,9 +874,6 @@ H5P_create_prop(const char *name, size_t size, void *def_value, void *value,
     prop->copy=prp_copy;
     prop->close=prp_close;
 
-    /* Reset the link to the next property */
-    prop->next=NULL;
-
     /* Set return value */
     ret_value=prop;
 
@@ -755,9 +885,7 @@ done:
                 H5MM_xfree(prop->name);
             if(prop->value!=NULL)
                 H5MM_xfree(prop->value);
-            if(prop->def_value!=NULL)
-                H5MM_xfree(prop->def_value);
-            H5MM_xfree(prop);
+            H5FL_FREE(H5P_genprop_t,prop);
         } /* end if */
     } /* end if */
 
@@ -769,95 +897,142 @@ done:
  NAME
     H5P_add_prop
  PURPOSE
-    Internal routine to insert a property into a property hash table
+    Internal routine to insert a property into a property TBBT
  USAGE
-    herr_t H5P_add_prop(hash, hashsize, prop)
-        H5P_gen_prop_t *hash[]; IN/OUT: Pointer to array of properties for hash table
-        unsigned hashsize;         IN: Size of hash table
+    herr_t H5P_add_prop(tree, prop)
+        H5TB_TREE *tree;        IN/OUT: Pointer to TBBT of properties
         H5P_genprop_t *prop;    IN: Pointer to property to insert
  RETURNS
     Returns non-negative on success, negative on failure.
  DESCRIPTION
-    Inserts a property into a hash table of properties, using the hashed
-    property name.
+    Inserts a property into a TBBT of properties.
  GLOBAL VARIABLES
  COMMENTS, BUGS, ASSUMPTIONS
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
 herr_t
-H5P_add_prop(H5P_genprop_t *hash[], unsigned hashsize, H5P_genprop_t *prop)
+H5P_add_prop(H5TB_TREE *tree, H5P_genprop_t *prop)
 {
-    unsigned loc;                  /* Hash table location */
+    herr_t      ret_value=SUCCEED;       /* Return value */
 
-    FUNC_ENTER_NOINIT(H5P_add_prop);
+    FUNC_ENTER_NOAPI(H5P_add_prop,FAIL);
 
-    assert(hash);
-    assert(hashsize>0);
+    assert(tree);
     assert(prop);
+    assert(prop->type!=H5P_PROP_WITHIN_UNKNOWN);
 
-    /* Get correct hash table location */
-    loc=H5P_hash_name(prop->name,hashsize);
-    
-    /* Insert property into hash table */
-    prop->next=hash[loc];
-    hash[loc]=prop;
+    /* Insert property into TBBT */
+    if(H5TB_dins(tree,prop,prop->name)==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,FAIL,"can't insert property into TBBT");
 
-    FUNC_LEAVE (SUCCEED);
+done:
+    FUNC_LEAVE(ret_value);
 }   /* H5P_add_prop() */
 
 
 /*--------------------------------------------------------------------------
  NAME
-    H5P_find_prop
+    H5P_find_prop_plist
  PURPOSE
-    Internal routine to check for a property in a hash table
+    Internal routine to check for a property in a property list's TBBT
  USAGE
-    H5P_genprop_t *H5P_find_prop(hash, hashsize, name)
-        H5P_genprop_t *hash[];  IN: Pointer to array of properties for hash table
-        unsigned hashsize;         IN: Size of hash table
+    H5P_genprop_t *H5P_find_prop(plist, name)
+        H5P_genplist_t *plist;  IN: Pointer to property list to check
         const char *name;       IN: Name of property to check for
  RETURNS
     Returns pointer to property on success, NULL on failure.
  DESCRIPTION
-        Checks for a property in a hash table of properties.
+    Checks for a property in a property list's TBBT of properties.
  GLOBAL VARIABLES
  COMMENTS, BUGS, ASSUMPTIONS
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
 static H5P_genprop_t *
-H5P_find_prop(H5P_genprop_t *hash[], unsigned hashsize, const char *name)
+H5P_find_prop_plist(H5P_genplist_t *plist, const char *name)
 {
+    H5TB_NODE *prop_node;       /* TBBT node holding property */
     H5P_genprop_t *ret_value;   /* Property pointer return value */
-    unsigned loc;                  /* Hash table location */
-    unsigned xor_val;              /* XOR'ed value of the name to look for */
 
-    FUNC_ENTER_NOINIT(H5P_find_prop);
+    FUNC_ENTER_NOINIT(H5P_find_prop_plist);
 
-    assert(hash);
-    assert(hashsize>0);
+    assert(plist);
     assert(name);
 
-    /* Get correct hash table location */
-    loc=H5P_hash_name(name,hashsize);
-    
-    /* Get the XOR'ed value for the name to search for, to speed up comparisons */
-    xor_val=H5P_xor_name(name);
-    
-    /* Locate property in list */
-    ret_value=hash[loc];
-    while(ret_value!=NULL) {
-        /* Check for name matching */
-        if(ret_value->xor_val==xor_val && HDstrcmp(ret_value->name,name)==0)
-            break;
-        
-        /* Advance to the next property */
-        ret_value=ret_value->next;
-    } /* end while */
+    /* Check if the property has been deleted from list */
+    if(H5TB_dfind(plist->del,name,NULL)!=NULL) {
+        HGOTO_ERROR(H5E_PLIST,H5E_NOTFOUND,NULL,"can't find property in TBBT");
+    } /* end if */
+    else {
+        /* Get the property node from the TBBT */
+        if((prop_node=H5TB_dfind(plist->props,name,NULL))!=NULL) {
+            /* Get the property from the node */
+            ret_value=prop_node->data;
+        } /* end if */
+        else {
+            H5P_genclass_t *tclass;     /* Temporary class pointer */
+
+            tclass=plist->pclass;
+            while(tclass!=NULL) {
+                /* Find the property in the class */
+                if((prop_node=H5TB_dfind(tclass->props,name,NULL))!=NULL)
+                    /* Get pointer to actual property & leave */
+                    HGOTO_DONE(prop_node->data);
+
+                /* Go up to parent class */
+                tclass=tclass->parent;
+            } /* end while */
+
+            /* If we've gotten this far, we haven't found the property */
+            HGOTO_ERROR(H5E_PLIST,H5E_NOTFOUND,NULL,"can't find property in TBBT");
+        } /* end else */
+    } /* end else */
+
+done:
+    FUNC_LEAVE (ret_value);
+}   /* H5P_find_prop_plist() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5P_find_prop_pclass
+ PURPOSE
+    Internal routine to check for a property in a class TBBT
+ USAGE
+    H5P_genprop_t *H5P_find_prop_class(tree, name)
+        H5P_genclass *pclass;   IN: Pointer generic property class to check
+        const char *name;       IN: Name of property to check for
+ RETURNS
+    Returns pointer to property on success, NULL on failure.
+ DESCRIPTION
+    Checks for a property in a class' TBBT of properties.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+static H5P_genprop_t *
+H5P_find_prop_pclass(H5P_genclass_t *pclass, const char *name)
+{
+    H5TB_NODE *prop_node;       /* TBBT node holding property */
+    H5P_genprop_t *ret_value;   /* Property pointer return value */
+
+    FUNC_ENTER_NOINIT(H5P_find_prop_pclass);
+
+    assert(pclass);
+    assert(name);
+
+    /* Get the property node from the TBBT */
+    if((prop_node=H5TB_dfind(pclass->props,name,NULL))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_NOTFOUND,NULL,"can't find property in TBBT");
+
+    /* Get the property from the node */
+    ret_value=prop_node->data;
 
+done:
     FUNC_LEAVE (ret_value);
-}   /* H5P_find_prop() */
+}   /* H5P_find_prop_pclass() */
 
 
 /*--------------------------------------------------------------------------
@@ -885,15 +1060,15 @@ H5P_free_prop(H5P_genprop_t *prop)
 
     assert(prop);
 
-    /* Release the property value and default value if they exist */
-    if(prop->size>0) {
-        if(prop->value)
-            H5MM_xfree(prop->value);
-        if(prop->def_value)
-            H5MM_xfree(prop->def_value);
-    } /* end if */
-    H5MM_xfree(prop->name);
-    H5MM_xfree(prop);
+    /* Release the property value if it exists */
+    if(prop->value)
+        H5MM_xfree(prop->value);
+
+    /* Only free the name if we own it */
+    if(prop->shared_name==0)
+        H5MM_xfree(prop->name);
+
+    H5FL_FREE(H5P_genprop_t,prop);
 
     FUNC_LEAVE (SUCCEED);
 }   /* H5P_free_prop() */
@@ -903,11 +1078,10 @@ H5P_free_prop(H5P_genprop_t *prop)
  NAME
     H5P_free_all_prop
  PURPOSE
-    Internal routine to remove all properties from a property hash table
+    Internal routine to remove all properties from a property TBBT
  USAGE
-    herr_t H5P_free_all_prop(hash, hashsize, make_cb)
-        H5P_gen_prop_t *hash[]; IN/OUT: Pointer to array of properties for hash table
-        unsigned hashsize;         IN: Size of hash table
+    herr_t H5P_free_all_prop(tree, make_cb)
+        H5TB_TREE *tree;           IN/OUT: Pointer to property TBBT
         unsigned make_cb;          IN: Whether to make property callbacks or not
  RETURNS
     Returns non-negative on success, negative on failure.
@@ -920,35 +1094,39 @@ H5P_free_prop(H5P_genprop_t *prop)
  REVISION LOG
 --------------------------------------------------------------------------*/
 static herr_t
-H5P_free_all_prop(H5P_genprop_t *hash[], unsigned hashsize, unsigned make_cb)
+H5P_free_all_prop(H5TB_TREE *tree,unsigned make_cb)
 {
-    H5P_genprop_t *tprop, *next;/* Temporary pointer to properties */
-    unsigned u;                    /* Local index variable */
+    H5P_genprop_t *tprop;       /* Temporary pointer to properties */
+    H5TB_NODE *curr_node, *next_node;   /* Current & next nodes in TBBT */
+    herr_t      ret_value=SUCCEED;      /* Return value */
 
     FUNC_ENTER_NOINIT(H5P_free_all_prop);
 
-    assert(hash);
-    assert(hashsize>0);
+    assert(tree);
 
     /* Work through all the properties... */
-    for(u=0; u<hashsize; u++) {
-        tprop=hash[u];
-        while(tprop!=NULL) {
-            /* Find next node right away, to avoid accessing the current node after it's been free'd */
-            next=tprop->next;
+    curr_node=H5TB_first(tree->root);
+    while(curr_node!=NULL) {
+        /* Get the next node in the TBBT */
+        next_node=H5TB_next(curr_node);
 
-            /* Call the close callback and ignore the return value, there's nothing we can do about it */
-            if(make_cb && tprop->close!=NULL)
-                (tprop->close)(tprop->name,tprop->size,tprop->value);
+        /* Remove the node from the TBBT */
+        if((tprop=H5TB_rem(&tree->root,curr_node,NULL))==NULL)
+            HGOTO_ERROR(H5E_PLIST,H5E_CANTDELETE,FAIL,"can't remove property from TBBT");
 
-            /* Free the property, ignoring return value, nothing we can do */
-            H5P_free_prop(tprop);
+        /* Call the close callback and ignore the return value, there's nothing we can do about it */
+        if(make_cb && tprop->close!=NULL)
+            (tprop->close)(tprop->name,tprop->size,tprop->value);
 
-            tprop=next;
-        } /* end while */
-    } /* end for */
+        /* Free the property, ignoring return value, nothing we can do */
+        H5P_free_prop(tprop);
 
-    FUNC_LEAVE (SUCCEED);
+        /* Advance to the next property node in the TBBT */
+        curr_node=next_node;
+    } /* end while */
+
+done:
+    FUNC_LEAVE (ret_value);
 }   /* H5P_free_all_prop() */
 
 
@@ -1027,9 +1205,13 @@ H5P_access_class(H5P_genclass_t *pclass, H5P_class_mod_t mod)
         H5MM_xfree(pclass->name);
 
         /* Free the class properties without making callbacks */
-        H5P_free_all_prop(pclass->props,pclass->hashsize,0);
+        if(pclass->nprops>0)
+            H5P_free_all_prop(pclass->props,0);
 
-        H5MM_xfree(pclass);
+        /* Free the property tree itself */
+        H5TB_dfree(pclass->props,NULL,NULL);
+
+        H5FL_FREE(H5P_genclass_t,pclass);
 
         /* Reduce the number of dependent classes on parent class also */
         if(par_class!=NULL)
@@ -1091,11 +1273,10 @@ H5P_check_class(void *_obj, hid_t id, const void *_key)
  PURPOSE
     Internal routine to create a new property list class.
  USAGE
-    H5P_genclass_t H5P_create_class(par_class, name, hashsize, internal,
+    H5P_genclass_t H5P_create_class(par_class, name, internal,
                 cls_create, create_data, cls_close, close_data)
         H5P_genclass_t *par_class;  IN: Pointer to parent class
         const char *name;       IN: Name of class we are creating
-        unsigned hashsize; IN: Number of buckets in hash table
         unsigned internal; IN: Whether this is an internal class or not
         H5P_cls_create_func_t;  IN: The callback function to call when each
                                     property list in this class is created.
@@ -1120,7 +1301,7 @@ H5P_check_class(void *_obj, hid_t id, const void *_key)
  REVISION LOG
 --------------------------------------------------------------------------*/
 static H5P_genclass_t *
-H5P_create_class(H5P_genclass_t *par_class, const char *name, unsigned hashsize, unsigned internal,
+H5P_create_class(H5P_genclass_t *par_class, const char *name, unsigned internal,
     H5P_cls_create_func_t cls_create, void *create_data,
     H5P_cls_copy_func_t cls_copy, void *copy_data,
     H5P_cls_close_func_t cls_close, void *close_data
@@ -1136,23 +1317,26 @@ H5P_create_class(H5P_genclass_t *par_class, const char *name, unsigned hashsize,
     /* (This allows the root of the tree to be created with this routine -QAK) */
     if(!internal) {
         assert(par_class);
-        assert(hashsize>0);
     }
 
-    /* Allocate room for the class & it's hash table of properties */
-    if (NULL==(pclass = H5MM_calloc (sizeof(H5P_genclass_t)+((hashsize-1)*sizeof(H5P_genprop_t *)))))
+    /* Allocate room for the class */
+    if (NULL==(pclass = H5FL_CALLOC(H5P_genclass_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL,"memory allocation failed");
 
     /* Set class state */
     pclass->parent = par_class;
     pclass->name = H5MM_xstrdup(name);
     pclass->nprops = 0;     /* Classes are created without properties initially */
-    pclass->hashsize = hashsize;
     pclass->plists = 0;     /* No properties lists of this class yet */
     pclass->classes = 0;    /* No classes derived from this class yet */
     pclass->ref_count = 1;  /* This is the first reference to the new class */
     pclass->internal = internal;
     pclass->deleted = 0;    /* Not deleted yet... :-) */
+    pclass->revision = H5P_GET_NEXT_REV;        /* Get a revision number for the class */
+
+    /* Create the TBBT for properties */
+    if((pclass->props=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,NULL,"can't create TBBT for properties");
 
     /* Set callback functions and pass-along data */
     pclass->create_func = cls_create;
@@ -1175,7 +1359,7 @@ done:
     /* Free any resources allocated */
     if(ret_value==NULL) {
         if(pclass!=NULL)
-            H5MM_xfree(pclass);
+            H5FL_FREE(H5P_genclass_t,pclass);
     }
 
     FUNC_LEAVE (ret_value);
@@ -1188,11 +1372,10 @@ done:
  PURPOSE
     Create a new property list class.
  USAGE
-    hid_t H5Pcreate_class(parent, name, hashsize, cls_create, create_data,
+    hid_t H5Pcreate_class(parent, name, cls_create, create_data,
                 cls_close, close_data)
         hid_t parent;       IN: Property list class ID of parent class
         const char *name;   IN: Name of class we are creating
-        unsigned hashsize;     IN: Number of buckets in hash table
         H5P_cls_create_func_t cls_create;   IN: The callback function to call
                                     when each property list in this class is
                                     created.
@@ -1218,7 +1401,7 @@ done:
  REVISION LOG
 --------------------------------------------------------------------------*/
 hid_t
-H5Pcreate_class(hid_t parent, const char *name, unsigned hashsize,
+H5Pcreate_class(hid_t parent, const char *name, 
     H5P_cls_create_func_t cls_create, void *create_data,
     H5P_cls_copy_func_t cls_copy, void *copy_data,
     H5P_cls_close_func_t cls_close, void *close_data
@@ -1229,7 +1412,7 @@ H5Pcreate_class(hid_t parent, const char *name, unsigned hashsize,
     hid_t	ret_value;                  /* Return value		   */
 
     FUNC_ENTER_API(H5Pcreate_class, FAIL);
-    H5TRACE9("i","isIuxxxxxx",parent,name,hashsize,cls_create,create_data,
+    H5TRACE8("i","isxxxxxx",parent,name,cls_create,create_data,
              cls_copy,copy_data,cls_close,close_data);
 
     /* Check arguments. */
@@ -1237,8 +1420,6 @@ H5Pcreate_class(hid_t parent, const char *name, unsigned hashsize,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list class");
     if (!name || !*name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid class name");
-    if (hashsize==0)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "hashsize too small");
     if ((create_data!=NULL && cls_create==NULL)
             || (copy_data!=NULL && cls_copy==NULL)
             || (close_data!=NULL && cls_close==NULL))
@@ -1251,7 +1432,7 @@ H5Pcreate_class(hid_t parent, const char *name, unsigned hashsize,
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "can't retrieve parent class");
 
     /* Create the new property list class */
-    if (NULL==(pclass=H5P_create_class(par_class, name, hashsize, 0, cls_create, create_data, cls_copy, copy_data, cls_close, close_data)))
+    if (NULL==(pclass=H5P_create_class(par_class, name, 0, cls_create, create_data, cls_copy, copy_data, cls_close, close_data)))
         HGOTO_ERROR(H5E_PLIST, H5E_CANTCREATE, FAIL, "unable to create property list class");
 
     /* Get an atom for the class */
@@ -1291,14 +1472,14 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-static H5P_genplist_t *H5P_create(H5P_genclass_t *pclass)
+static H5P_genplist_t *
+H5P_create(H5P_genclass_t *pclass)
 {
-    H5P_genclass_t *tclass=NULL;        /* Temporary class pointer */
-    H5P_genplist_t *plist=NULL;         /* New property list created */
-    H5P_genplist_t *ret_value;          /* return value */
-    H5P_genprop_t *tmp;                 /* Temporary pointer to parent class properties */
-    H5P_genprop_t *pcopy;               /* Copy of property to insert into class */
-    unsigned u;                         /* Local index variable */
+    H5P_genclass_t *tclass;         /* Temporary class pointer */
+    H5P_genplist_t *plist=NULL;     /* New property list created */
+    H5P_genprop_t *tmp;             /* Temporary pointer to parent class properties */
+    H5TB_TREE *seen=NULL;           /* TBBT to hold names of properties already seen */
+    H5P_genplist_t *ret_value;      /* Return value */
 
     FUNC_ENTER_NOINIT(H5P_create);
 
@@ -1308,8 +1489,8 @@ static H5P_genplist_t *H5P_create(H5P_genclass_t *pclass)
      * Create new property list object
      */
 
-    /* Allocate room for the property list & it's hash table of properties */
-    if (NULL==(plist = H5MM_calloc (sizeof(H5P_genplist_t)+((pclass->hashsize-1)*sizeof(H5P_genprop_t *)))))
+    /* Allocate room for the property list */
+    if (NULL==(plist = H5FL_CALLOC(H5P_genplist_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL,"memory allocation failed");
 
     /* Set class state */
@@ -1317,57 +1498,57 @@ static H5P_genplist_t *H5P_create(H5P_genclass_t *pclass)
     plist->nprops = 0;      /* Initially the plist has the same number of properties as the class */
     plist->class_init = 0;  /* Initially, wait until the class callback finishes to set */
 
+    /* Create the TBBT for changed properties */
+    if((plist->props=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,NULL,"can't create TBBT for changed properties");
+
+    /* Create the TBBT for deleted properties */
+    if((plist->del=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,NULL,"can't create TBBT for deleted properties");
+
+    /* Create the TBBT to hold names of properties already seen
+     * (This prevents a property in the class hierarchy from having it's
+     * 'create' callback called, if a property in the class hierarchy has
+     * already been seen)
+     */
+    if((seen=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,NULL,"can't create TBBT for seen properties");
+
     /*
-     * Copy class properties (up through list of parent classes also),
+     * Check if we should copy class properties (up through list of parent classes also),
      * initialize each with default value & make property 'create' callback.
      */
     tclass=pclass;
     while(tclass!=NULL) {
         if(tclass->nprops>0) {
-            /* Walk through the hash table */
-            for(u=0; u<tclass->hashsize; u++) {
-                tmp=tclass->props[u];
-                /* Walk through the list of properties at each hash location */
-                while(tmp!=NULL) {
-                    /* Check for property already existing in list */
-                    if(H5P_find_prop(plist->props,pclass->hashsize,tmp->name)==NULL) {
-                        /* Make a copy of the class's property */
-                        if((pcopy=H5P_dup_prop(tmp))==NULL)
-                            HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, NULL,"Can't copy property");
-
-                        /* Create initial value from default value for non-zero sized properties */
-                        if(pcopy->size>0) {
-                            /* Properties from the class should have any values yet, but should have a default */
-                            assert(pcopy->value==NULL);
-                            assert(pcopy->def_value);
-
-                            /* Allocate space for the property value & copy default value */
-                            if (NULL==(pcopy->value = H5MM_malloc (pcopy->size)))
-                                HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
-
-                            HDmemcpy(pcopy->value,pcopy->def_value,pcopy->size);
-                        } /* end if */
-
-                        /* Call property creation callback, if it exists */
-                        if(pcopy->create) {
-                            if((pcopy->create)(pcopy->name,pcopy->size,pcopy->value)<0) {
-                                H5P_free_prop(pcopy);
-                                HGOTO_ERROR (H5E_PLIST, H5E_CANTINIT, NULL,"Can't initialize property");
-                            } /* end if */
-                        } /* end if */
+            H5TB_NODE *curr_node;   /* Current node in TBBT */
+
+            /* Walk through the properties in the old class */
+            curr_node=H5TB_first(tclass->props->root);
+            while(curr_node!=NULL) {
+                /* Get pointer to property from node */
+                tmp=curr_node->data;
+
+                /* Only "create" properties we haven't seen before */
+                if(H5TB_dfind(seen,tmp->name,NULL)==NULL) {
+                    /* Call property creation callback, if it exists */
+                    if(tmp->create) {
+                        /* Call the callback & insert changed value into tree (if necessary) */
+                        if(H5P_do_prop_cb1(plist->props,tmp,tmp->create)<0)
+                            HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, NULL,"Can't create property");
+                    } /* end if */
 
-                        /* Insert the initialized property into the property list */
-                        if(H5P_add_prop(plist->props,pclass->hashsize,pcopy)<0)
-                            HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, NULL,"Can't insert property into class");
+                    /* Add property name to "seen" list */
+                    if(H5TB_dins(seen,tmp->name,tmp->name)==NULL)
+                        HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,NULL,"can't insert property into seen TBBT");
 
-                        /* Increment the number of properties in list */
-                        plist->nprops++;
-                    } /* end if */
+                    /* Increment the number of properties in list */
+                    plist->nprops++;
+                } /* end if */
 
-                    /* Go to next registered property in class */
-                    tmp=tmp->next;
-                } /* end while */
-            } /* end for */
+                /* Get the next property node in the TBBT */
+                curr_node=H5TB_next(curr_node);
+            } /* end while */
         } /* end if */
 
         /* Go up to parent class */
@@ -1382,14 +1563,25 @@ static H5P_genplist_t *H5P_create(H5P_genclass_t *pclass)
     ret_value=plist;
 
 done:
+    /* Release the tree of 'seen' properties */
+    if(seen!=NULL)
+        H5TB_dfree(seen,NULL,NULL);
+
     /* Release resources allocated on failure */
     if(ret_value==NULL) {
         if(plist!=NULL) {
-            /* Close & free all the properties */
-            H5P_free_all_prop(plist->props,pclass->hashsize,1);
+            /* Close & free any changed properties */
+            if(plist->props) {
+                H5P_free_all_prop(plist->props,1);
+                H5TB_dfree(plist->props,NULL,NULL);
+            } /* end if */
 
-            /* Decrement the number of property lists derived from the class */
-            pclass->plists--;
+            /* Release the deleted property TBBT */
+            if(plist->del)
+                H5TB_dfree(plist->del,NULL,NULL);
+
+            /* Release the property list itself */
+            H5FL_FREE(H5P_genplist_t,plist);
         } /* end if */
     } /* end if */
 
@@ -1419,7 +1611,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-hid_t H5P_create_id(H5P_genclass_t *pclass)
+hid_t
+H5P_create_id(H5P_genclass_t *pclass)
 {
     H5P_genplist_t	*plist=NULL;    /* Property list created */
     hid_t plist_id=FAIL;        /* Property list ID */
@@ -1485,7 +1678,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-hid_t H5Pcreate(hid_t cls_id)
+hid_t
+H5Pcreate(hid_t cls_id)
 {
     H5P_genclass_t	*pclass;   /* Property list class to modify */
     hid_t ret_value;               /* return value */
@@ -1636,16 +1830,15 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5P_register(H5P_genclass_t *pclass, const char *name, size_t size,
+herr_t
+H5P_register(H5P_genclass_t *pclass, const char *name, size_t size,
     void *def_value, H5P_prp_create_func_t prp_create, H5P_prp_set_func_t prp_set,
     H5P_prp_get_func_t prp_get, H5P_prp_delete_func_t prp_delete,
     H5P_prp_copy_func_t prp_copy, H5P_prp_close_func_t prp_close)
 {
     H5P_genclass_t *new_class; /* New class pointer */
-    H5P_genprop_t *tmp_prop;   /* Temporary property pointer */
     H5P_genprop_t *new_prop=NULL;   /* Temporary property pointer */
     H5P_genprop_t *pcopy;      /* Property copy */
-    unsigned u;                   /* Local index variable */
     herr_t      ret_value=SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5P_register, FAIL);
@@ -1655,51 +1848,60 @@ herr_t H5P_register(H5P_genclass_t *pclass, const char *name, size_t size,
     assert((size>0 && def_value!=NULL) || (size==0));
 
     /* Check for duplicate named properties */
-    if((tmp_prop=H5P_find_prop(pclass->props,pclass->hashsize,name))!=NULL)
+    if(H5TB_dfind(pclass->props,name,NULL)!=NULL)
         HGOTO_ERROR(H5E_PLIST, H5E_EXISTS, FAIL, "property already exists");
 
     /* Check if class needs to be split because property lists or classes have
      *  been created since the last modification was made to the class.
      */
     if(pclass->plists>0 || pclass->classes>0) {
-        if((new_class=H5P_create_class(pclass->parent,pclass->name,pclass->hashsize,
+        if((new_class=H5P_create_class(pclass->parent,pclass->name,
                 pclass->internal,pclass->create_func,pclass->create_data,
                 pclass->copy_func,pclass->copy_data,
                 pclass->close_func,pclass->close_data))==NULL)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTCOPY, FAIL, "can't copy class");
 
-        /* Walk through the hash table of the old class and copy properties */
-        for(u=0; u<pclass->hashsize; u++) {
-            tmp_prop=pclass->props[u];
-            while(tmp_prop!=NULL) {
+        /* Walk through the TBBT of the old class and copy properties */
+        if(pclass->nprops>0) {
+            H5TB_NODE *curr_node;   /* Current node in TBBT */
+
+            /* Walk through the properties in the old class */
+            curr_node=H5TB_first(pclass->props->root);
+            while(curr_node!=NULL) {
                 /* Make a copy of the class's property */
-                if((pcopy=H5P_dup_prop(tmp_prop))==NULL)
-                    HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, FAIL,"Can't copy property");
+                if((pcopy=H5P_dup_prop(curr_node->data,H5P_PROP_WITHIN_CLASS))==NULL)
+                    HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, NULL,"Can't copy property");
+
+                /* Insert the initialized property into the property list */
+                if(H5P_add_prop(new_class->props,pcopy)<0)
+                    HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, NULL,"Can't insert property into class");
 
-                /* Insert the property into the new property class */
-                if(H5P_add_prop(new_class->props,pclass->hashsize,pcopy)<0)
-                    HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, FAIL,"Can't insert property into class");
+                /* Increment property count for class */
+                new_class->nprops++;
 
-                /* Go to next registered property in class */
-                tmp_prop=tmp_prop->next;
+                /* Get the next property node in the TBBT */
+                curr_node=H5TB_next(curr_node);
             } /* end while */
-        } /* end for */
+        } /* end if */
 
         /* Use the new class instead of the old one */
         pclass=new_class;
     } /* end if */
 
     /* Create property object from parameters */
-    if((new_prop=H5P_create_prop(name,size,def_value,NULL,prp_create,prp_set,prp_get,prp_delete,prp_copy,prp_close))==NULL)
+    if((new_prop=H5P_create_prop(name,size,H5P_PROP_WITHIN_CLASS,def_value,prp_create,prp_set,prp_get,prp_delete,prp_copy,prp_close))==NULL)
         HGOTO_ERROR (H5E_PLIST, H5E_CANTCREATE, FAIL,"Can't create property");
 
     /* Insert property into property list class */
-    if(H5P_add_prop(pclass->props,pclass->hashsize,new_prop)<0)
+    if(H5P_add_prop(pclass->props,new_prop)<0)
         HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, FAIL,"Can't insert property into class");
 
     /* Increment property count for class */
     pclass->nprops++;
 
+    /* Update the revision for the class */
+    pclass->revision = H5P_GET_NEXT_REV;
+
 done:
     if(ret_value==FAIL) {
         if(new_prop!=NULL) {
@@ -1707,9 +1909,7 @@ done:
                 H5MM_xfree(new_prop->name);
             if(new_prop->value!=NULL)
                 H5MM_xfree(new_prop->value);
-            if(new_prop->def_value!=NULL)
-                H5MM_xfree(new_prop->def_value);
-            H5MM_xfree(new_prop);
+            H5FL_FREE(H5P_genprop_t,new_prop);
         } /* end if */
     }  /* end if */
     FUNC_LEAVE (ret_value);
@@ -1847,7 +2047,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5Pregister(hid_t cls_id, const char *name, size_t size, void *def_value,
+herr_t
+H5Pregister(hid_t cls_id, const char *name, size_t size, void *def_value,
     H5P_prp_create_func_t prp_create, H5P_prp_set_func_t prp_set,
     H5P_prp_get_func_t prp_get, H5P_prp_delete_func_t prp_delete,
     H5P_prp_copy_func_t prp_copy, H5P_prp_close_func_t prp_close)
@@ -1986,8 +2187,9 @@ H5P_insert(H5P_genplist_t *plist, const char *name, size_t size,
     H5P_prp_delete_func_t prp_delete, H5P_prp_copy_func_t prp_copy, 
     H5P_prp_close_func_t prp_close)
 {
-    H5P_genprop_t *new_prop=NULL;   /* Temporary property pointer */
-    herr_t      ret_value=SUCCEED;       /* Return value */
+    H5P_genprop_t *new_prop=NULL;       /* Temporary property pointer */
+    H5TB_NODE *prop_node;               /* TBBT node holding property */
+    herr_t ret_value=SUCCEED;           /* Return value */
 
     FUNC_ENTER_NOINIT(H5P_insert);
 
@@ -1996,15 +2198,44 @@ H5P_insert(H5P_genplist_t *plist, const char *name, size_t size,
     assert((size>0 && value!=NULL) || (size==0));
 
     /* Check for duplicate named properties */
-    if(H5P_find_prop(plist->props,plist->pclass->hashsize,name)!=NULL)
+    if(H5TB_dfind(plist->props,name,NULL)!=NULL)
         HGOTO_ERROR(H5E_PLIST, H5E_EXISTS, FAIL, "property already exists");
 
+    /* Check if the property has been deleted */
+    if((prop_node=H5TB_dfind(plist->del,name,NULL))!=NULL) {
+        /* Remove the property name from the deleted property TBBT */
+        if(H5TB_rem(&plist->del->root,prop_node,NULL)==NULL)
+            HGOTO_ERROR(H5E_PLIST,H5E_CANTDELETE,FAIL,"can't remove property from deleted TBBT");
+
+        /* Fall through to add property to list */
+    } /* end if */
+    else {
+        H5P_genclass_t *tclass;     /* Temporary class pointer */
+
+        /* Check if the property is already in the class hierarchy */
+        tclass=plist->pclass;
+        while(tclass!=NULL) {
+            if(tclass->nprops>0) {
+                /* Find the property in the class */
+                if(H5TB_dfind(tclass->props,name,NULL)!=NULL)
+                    HGOTO_ERROR(H5E_PLIST, H5E_EXISTS, FAIL, "property already exists");
+            } /* end if */
+
+            /* Go up to parent class */
+            tclass=tclass->parent;
+        } /* end while */
+
+        /* Fall through to add property to list */
+    } /* end else */
+
+    /* Ok to add to property list */
+
     /* Create property object from parameters */
-    if((new_prop=H5P_create_prop(name,size,NULL,value,NULL,prp_set,prp_get,prp_delete,prp_copy,prp_close))==NULL)
+    if((new_prop=H5P_create_prop(name,size,H5P_PROP_WITHIN_LIST,value,NULL,prp_set,prp_get,prp_delete,prp_copy,prp_close))==NULL)
         HGOTO_ERROR (H5E_PLIST, H5E_CANTCREATE, FAIL,"Can't create property");
 
     /* Insert property into property list class */
-    if(H5P_add_prop(plist->props,plist->pclass->hashsize,new_prop)<0)
+    if(H5P_add_prop(plist->props,new_prop)<0)
         HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, FAIL,"Can't insert property into class");
 
     /* Increment property count for class */
@@ -2017,9 +2248,7 @@ done:
                 H5MM_xfree(new_prop->name);
             if(new_prop->value!=NULL)
                 H5MM_xfree(new_prop->value);
-            if(new_prop->def_value!=NULL)
-                H5MM_xfree(new_prop->def_value);
-            H5MM_xfree(new_prop);
+            H5FL_FREE(H5P_genprop_t,new_prop);
         } /* end if */
     }  /* end if */
 
@@ -2132,7 +2361,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5Pinsert(hid_t plist_id, const char *name, size_t size, void *value,
+herr_t
+H5Pinsert(hid_t plist_id, const char *name, size_t size, void *value,
     H5P_prp_set_func_t prp_set, H5P_prp_get_func_t prp_get,
     H5P_prp_delete_func_t prp_delete, H5P_prp_copy_func_t prp_copy, 
     H5P_prp_close_func_t prp_close)
@@ -2190,9 +2420,12 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5P_set(H5P_genplist_t *plist, const char *name, const void *value)
+herr_t
+H5P_set(H5P_genplist_t *plist, const char *name, const void *value)
 {
+    H5P_genclass_t *tclass;     /* Temporary class pointer */
     H5P_genprop_t *prop;        /* Temporary property pointer */
+    H5TB_NODE *prop_node;       /* TBBT node holding property */
     herr_t      ret_value=SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5P_set, FAIL);
@@ -2201,36 +2434,123 @@ herr_t H5P_set(H5P_genplist_t *plist, const char *name, const void *value)
     assert(name);
     assert(value);
 
-    /* Find property */
-    if((prop=H5P_find_prop(plist->props,plist->pclass->hashsize,name))==NULL)
+    /* Check if the property has been deleted */
+    if(H5TB_dfind(plist->del,name,NULL)!=NULL)
         HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "property doesn't exist");
 
-    /* Check for property size >0 */
-    if(prop->size==0)
-        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "property has zero size");
+    /* Find property in changed list */
+    if((prop_node=H5TB_dfind(plist->props,name,NULL))!=NULL) {
+        /* Get pointer to actual property */
+        prop=prop_node->data;
+
+        /* Check for property size >0 */
+        if(prop->size==0)
+            HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "property has zero size");
 
-    /* Make a copy of the value and pass to 'set' callback */
-    if(prop->set!=NULL) {
-        void *tmp_value;            /* Temporary value for property */
+        /* Make a copy of the value and pass to 'set' callback */
+        if(prop->set!=NULL) {
+            void *tmp_value;            /* Temporary value for property */
 
-        /* Make a copy of the current value, in case the callback fails */
-        if (NULL==(tmp_value=H5MM_malloc(prop->size)))
-            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed temporary property value");
-        HDmemcpy(tmp_value,value,prop->size);
+            /* Make a copy of the current value, in case the callback fails */
+            if (NULL==(tmp_value=H5MM_malloc(prop->size)))
+                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed temporary property value");
+            HDmemcpy(tmp_value,value,prop->size);
 
-        /* Call user's callback */
-        if((*(prop->set))(plist->plist_id,name,prop->size,tmp_value)<0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't set property value");
+            /* Call user's callback */
+            if((*(prop->set))(plist->plist_id,name,prop->size,tmp_value)<0) {
+                H5MM_xfree(tmp_value);
+                HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't set property value");
+            } /* end if */
 
-        /* Copy new [possibly unchanged] value into property value */
-        HDmemcpy(prop->value,tmp_value,prop->size);
+            /* Copy new [possibly unchanged] value into property value */
+            HDmemcpy(prop->value,tmp_value,prop->size);
 
-        /* Free the temporary value buffer */
-        H5MM_xfree(tmp_value);
+            /* Free the temporary value buffer */
+            H5MM_xfree(tmp_value);
+        } /* end if */
+        /* No 'set' callback, just copy value */
+        else
+            HDmemcpy(prop->value,value,prop->size);
     } /* end if */
-    /* No 'set' callback, just copy value */
-    else
-        HDmemcpy(prop->value,value,prop->size);
+    else {
+        /*
+         * Check if we should set class properties (up through list of parent classes also),
+         * & make property 'set' callback.
+         */
+        tclass=plist->pclass;
+        while(tclass!=NULL) {
+            if(tclass->nprops>0) {
+                /* Find the property in the class */
+                if((prop_node=H5TB_dfind(tclass->props,name,NULL))!=NULL) {
+                    H5P_genprop_t *pcopy;  /* Copy of property to insert into TBBT */
+
+                    /* Get pointer to actual property */
+                    prop=prop_node->data;
+
+                    /* Check for property size >0 */
+                    if(prop->size==0)
+                        HGOTO_ERROR(H5E_PLIST,H5E_BADVALUE,FAIL,"property has zero size");
+
+                    /* Make a copy of the value and pass to 'set' callback */
+                    if(prop->set!=NULL) {
+                        void *tmp_value;            /* Temporary value for property */
+
+                        /* Make a copy of the current value, in case the callback fails */
+                        if (NULL==(tmp_value=H5MM_malloc(prop->size)))
+                            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed temporary property value");
+                        HDmemcpy(tmp_value,value,prop->size);
+
+                        /* Call user's callback */
+                        if((*(prop->set))(plist->plist_id,name,prop->size,tmp_value)<0) {
+                            H5MM_xfree(tmp_value);
+                            HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't set property value");
+                        } /* end if */
+
+                        if(HDmemcmp(tmp_value,prop->value,prop->size)) {
+                            /* Make a copy of the class's property */
+                            if((pcopy=H5P_dup_prop(prop,H5P_PROP_WITHIN_LIST))==NULL)
+                                HGOTO_ERROR(H5E_PLIST,H5E_CANTCOPY,FAIL,"Can't copy property");
+
+                            /* Copy new value into property value */
+                            HDmemcpy(pcopy->value,tmp_value,pcopy->size);
+
+                            /* Insert the changed property into the property list */
+                            if(H5P_add_prop(plist->props,pcopy)<0)
+                                HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, FAIL,"Can't insert changed property into TBBT");
+                        } /* end if */
+
+                        /* Free the temporary value buffer */
+                        H5MM_xfree(tmp_value);
+                    } /* end if */
+                    /* No 'set' callback, just copy value */
+                    else {
+                        if(HDmemcmp(value,prop->value,prop->size)) {
+                            /* Make a copy of the class's property */
+                            if((pcopy=H5P_dup_prop(prop,H5P_PROP_WITHIN_LIST))==NULL)
+                                HGOTO_ERROR(H5E_PLIST,H5E_CANTCOPY,FAIL,"Can't copy property");
+
+                            HDmemcpy(pcopy->value,value,pcopy->size);
+
+                            /* Insert the changed property into the property list */
+                            if(H5P_add_prop(plist->props,pcopy)<0)
+                                HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, FAIL,"Can't insert changed property into TBBT");
+                        } /* end if */
+                    } /* end else */
+
+                    /* Leave */
+                    HGOTO_DONE(SUCCEED);
+                } /* end while */
+            } /* end if */
+
+            /* Go up to parent class */
+            tclass=tclass->parent;
+        } /* end while */
+
+        /* If we get this far, then it wasn't in the list of changed properties,
+         * nor in the properties in the class hierarchy, indicate an error
+         */
+        HGOTO_ERROR(H5E_PLIST,H5E_NOTFOUND,FAIL,"can't find property in TBBT");
+    } /* end else */
 
 done:
     FUNC_LEAVE (ret_value);
@@ -2268,7 +2588,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5Pset(hid_t plist_id, const char *name, void *value)
+herr_t
+H5Pset(hid_t plist_id, const char *name, void *value)
 {
     H5P_genplist_t *plist;      /* Property list to modify */
     herr_t ret_value=SUCCEED;   /* return value */
@@ -2323,12 +2644,31 @@ H5P_exist_plist(H5P_genplist_t *plist, const char *name)
     assert(plist);
     assert(name);
 
-    /* Check for property in property list */
-    if(H5P_find_prop(plist->props,plist->pclass->hashsize,name)==NULL)
+    /* Check for property in deleted property list */
+    if(H5TB_dfind(plist->del,name,NULL)!=NULL)
         ret_value=0;
-    else
-        ret_value=1;
+    else {
+        /* Check for property in changed property list */
+        if(H5TB_dfind(plist->props,name,NULL)!=NULL)
+            ret_value=1;
+        else {
+            H5P_genclass_t *tclass;     /* Temporary class pointer */
+
+            tclass=plist->pclass;
+            while(tclass!=NULL) {
+                if(H5TB_dfind(tclass->props,name,NULL)!=NULL)
+                    HGOTO_DONE(1);
+
+                /* Go up to parent class */
+                tclass=tclass->parent;
+            } /* end while */
+
+            /* If we've reached here, we couldn't find the property */
+            ret_value=0;
+        } /* end else */
+    } /* end else */
 
+done:
     FUNC_LEAVE (ret_value);
 }   /* H5P_exist_plist() */
 
@@ -2365,7 +2705,7 @@ H5P_exist_pclass(H5P_genclass_t *pclass, const char *name)
     assert(name);
 
     /* Check for property in property list */
-    if(H5P_find_prop(pclass->props,pclass->hashsize,name)==NULL)
+    if(H5TB_dfind(pclass->props,name,NULL)==NULL)
         ret_value=0;
     else
         ret_value=1;
@@ -2396,7 +2736,8 @@ H5P_exist_pclass(H5P_genclass_t *pclass, const char *name)
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-htri_t H5Pexist(hid_t id, const char *name)
+htri_t
+H5Pexist(hid_t id, const char *name)
 {
     H5P_genplist_t	*plist;    /* Property list to query */
     H5P_genclass_t	*pclass;   /* Property class to query */
@@ -2467,7 +2808,7 @@ H5P_get_size_plist(H5P_genplist_t *plist, const char *name, size_t *size)
     assert(size);
 
     /* Find property */
-    if((prop=H5P_find_prop(plist->props,plist->pclass->hashsize,name))==NULL)
+    if((prop=H5P_find_prop_plist(plist,name))==NULL)
         HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "property doesn't exist");
 
     /* Get property size */
@@ -2513,7 +2854,7 @@ H5P_get_size_pclass(H5P_genclass_t *pclass, const char *name, size_t *size)
     assert(size);
 
     /* Find property */
-    if((prop=H5P_find_prop(pclass->props,pclass->hashsize,name))==NULL)
+    if((prop=H5P_find_prop_pclass(pclass,name))==NULL)
         HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "property doesn't exist");
 
     /* Get property size */
@@ -2547,7 +2888,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5Pget_size(hid_t id, const char *name, size_t *size)
+herr_t
+H5Pget_size(hid_t id, const char *name, size_t *size)
 {
     H5P_genclass_t	*pclass;   /* Property class to query */
     H5P_genplist_t	*plist;    /* Property list to query */
@@ -2643,7 +2985,8 @@ H5P_get_class(H5P_genplist_t *plist)
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-hid_t H5Pget_class(hid_t plist_id)
+hid_t
+H5Pget_class(hid_t plist_id)
 {
     H5P_genplist_t	*plist;         /* Property list to query */
     H5P_genclass_t	*pclass=NULL;   /* Property list class */
@@ -2730,7 +3073,8 @@ H5P_get_nprops_plist(H5P_genplist_t *plist, size_t *nprops)
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5P_get_nprops_pclass(H5P_genclass_t *pclass, size_t *nprops)
+herr_t
+H5P_get_nprops_pclass(H5P_genclass_t *pclass, size_t *nprops)
 {
     herr_t ret_value=SUCCEED;   /* Return value */
 
@@ -2770,7 +3114,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5Pget_nprops(hid_t id, size_t *nprops)
+herr_t
+H5Pget_nprops(hid_t id, size_t *nprops)
 {
     H5P_genplist_t	*plist;    /* Property list to query */
     H5P_genclass_t	*pclass;   /* Property class to query */
@@ -2853,13 +3198,6 @@ H5P_cmp_prop(H5P_genprop_t *prop1, H5P_genprop_t *prop2)
         if((cmp_value=HDmemcmp(prop1->value,prop2->value,prop1->size))!=0)
             HGOTO_DONE(cmp_value);
 
-    /* Check if they both have default values allocated (or not allocated) */
-    if(prop1->def_value==NULL && prop2->def_value!=NULL) HGOTO_DONE(-1);
-    if(prop1->def_value!=NULL && prop2->def_value==NULL) HGOTO_DONE(1);
-    if(prop1->def_value!=NULL)
-        if((cmp_value=HDmemcmp(prop1->def_value,prop2->def_value,prop1->size))!=0)
-            HGOTO_DONE(cmp_value);
-
     /* Check if they both have the same 'create' callback */
     if(prop1->create==NULL && prop2->create!=NULL) HGOTO_DONE(-1);
     if(prop1->create!=NULL && prop2->create==NULL) HGOTO_DONE(1);
@@ -2890,8 +3228,6 @@ H5P_cmp_prop(H5P_genprop_t *prop1, H5P_genprop_t *prop2)
     if(prop1->close!=NULL && prop2->close==NULL) HGOTO_DONE(1);
     if(prop1->close!=prop2->close) HGOTO_DONE(-1);
 
-    /* Don't check the 'next' field, they must be equal by now */
-
 done:
     FUNC_LEAVE (ret_value);
 }   /* H5P_cmp_prop() */
@@ -2922,16 +3258,19 @@ done:
 static int
 H5P_cmp_class(H5P_genclass_t *pclass1, H5P_genclass_t *pclass2)
 {
-    H5P_genprop_t *tprop1, *tprop2;/* Temporary pointer to properties */
-    unsigned u;                    /* Local index variable */
-    int cmp_value;             /* Value from comparison */
-    int ret_value=0;         /* return value */
+    H5TB_NODE *tnode1,*tnode2;      /* Temporary pointer to propery nodes */
+    int cmp_value;                  /* Value from comparison */
+    int ret_value=0;                /* Return value */
 
     FUNC_ENTER_NOINIT(H5P_cmp_class);
 
     assert(pclass1);
     assert(pclass2);
 
+    /* Use the revision number to quickly check for identical classes */
+    if(pclass1->revision==pclass2->revision)
+        HGOTO_DONE(0);
+
     /* Check the name */
     if((cmp_value=HDstrcmp(pclass1->name,pclass2->name))!=0)
         HGOTO_DONE(cmp_value);
@@ -2940,10 +3279,6 @@ H5P_cmp_class(H5P_genclass_t *pclass1, H5P_genclass_t *pclass2)
     if(pclass1->nprops < pclass2->nprops) HGOTO_DONE(-1);
     if(pclass1->nprops > pclass2->nprops) HGOTO_DONE(1);
 
-    /* Check the hashsize */
-    if(pclass1->hashsize < pclass2->hashsize) HGOTO_DONE(-1);
-    if(pclass1->hashsize > pclass2->hashsize) HGOTO_DONE(1);
-
     /* Check the number of property lists created from the class */
     if(pclass1->plists < pclass2->plists) HGOTO_DONE(-1);
     if(pclass1->plists > pclass2->plists) HGOTO_DONE(1);
@@ -2979,29 +3314,21 @@ H5P_cmp_class(H5P_genclass_t *pclass1, H5P_genclass_t *pclass2)
     if(pclass1->close_data > pclass2->close_data) HGOTO_DONE(1);
 
     /* Cycle through the properties and compare them also */
-    for(u=0; u<pclass1->hashsize; u++) {
-        tprop1=pclass1->props[u];
-        tprop2=pclass2->props[u];
-
-        /* Check if they both have properties in this hash location */
-        if(tprop1==NULL && tprop2!=NULL) HGOTO_DONE(-1);
-        if(tprop1!=NULL && tprop2==NULL) HGOTO_DONE(1);
-
-        /* Check the actual properties */
-        while(tprop1!=NULL && tprop2!=NULL) {
-            /* Compare the two properties */
-            if((cmp_value=H5P_cmp_prop(tprop1,tprop2))!=0)
-                HGOTO_DONE(cmp_value);
-
-            /* Advance the pointers */
-            tprop1=tprop1->next;
-            tprop2=tprop2->next;
+    tnode1=H5TB_first(pclass1->props->root);
+    tnode2=H5TB_first(pclass2->props->root);
+    while(tnode1 || tnode2) {
+        /* Check if they both have properties in this TBBT node */
+        if(tnode1==NULL && tnode2!=NULL) HGOTO_DONE(-1);
+        if(tnode1!=NULL && tnode2==NULL) HGOTO_DONE(1);
+
+        /* Compare the two properties */
+        if((cmp_value=H5P_cmp_prop(tnode1->data,tnode2->data))!=0)
+            HGOTO_DONE(cmp_value);
 
-            /* Check if they both have properties in this location */
-            if(tprop1==NULL && tprop2!=NULL) HGOTO_DONE(-1);
-            if(tprop1!=NULL && tprop2==NULL) HGOTO_DONE(1);
-        } /* end while */
-    } /* end for */
+        /* Advance the pointers */
+        tnode1=H5TB_next(tnode1);
+        tnode2=H5TB_next(tnode2);
+    } /* end while */
 
 done:
     FUNC_LEAVE (ret_value);
@@ -3033,8 +3360,7 @@ done:
 static int
 H5P_cmp_plist(H5P_genplist_t *plist1, H5P_genplist_t *plist2)
 {
-    H5P_genprop_t *tprop1, *tprop2;/* Temporary pointer to properties */
-    unsigned u;                    /* Local index variable */
+    H5TB_NODE *tnode1,*tnode2;      /* Temporary pointer to propery nodes */
     int cmp_value;             /* Value from comparison */
     int ret_value=0;         /* return value */
 
@@ -3043,10 +3369,6 @@ H5P_cmp_plist(H5P_genplist_t *plist1, H5P_genplist_t *plist2)
     assert(plist1);
     assert(plist2);
 
-    /* Check the parent class */
-    if(plist1->pclass < plist2->pclass) HGOTO_DONE(-1);
-    if(plist1->pclass > plist2->pclass) HGOTO_DONE(1);
-
     /* Check the number of properties */
     if(plist1->nprops < plist2->nprops) HGOTO_DONE(-1);
     if(plist1->nprops > plist2->nprops) HGOTO_DONE(1);
@@ -3055,24 +3377,57 @@ H5P_cmp_plist(H5P_genplist_t *plist1, H5P_genplist_t *plist2)
     if(plist1->class_init < plist2->class_init) HGOTO_DONE(-1);
     if(plist1->class_init > plist2->class_init) HGOTO_DONE(1);
 
-    /* Cycle through the properties and compare them also */
-    for(u=0; u<plist1->pclass->hashsize; u++) {
-        tprop1=plist1->props[u];
+    /* Check for identical deleted properties */
+    if(plist1->del->root) {
+        /* Check for no deleted properties in plist2 */
+        if(plist2->del->root==NULL) HGOTO_DONE(1);
+
+        tnode1=H5TB_first(plist1->del->root);
+        tnode2=H5TB_first(plist2->del->root);
+        while(tnode1 || tnode2) {
+            /* Check if they both have properties in this TBBT node */
+            if(tnode1==NULL && tnode2!=NULL) HGOTO_DONE(-1);
+            if(tnode1!=NULL && tnode2==NULL) HGOTO_DONE(1);
+
+            /* Compare the two deleted properties */
+            if((cmp_value=HDstrcmp(tnode1->data,tnode2->data))!=0)
+                HGOTO_DONE(cmp_value);
+
+            /* Advance the pointers */
+            tnode1=H5TB_next(tnode1);
+            tnode2=H5TB_next(tnode2);
+        } /* end while */
+    } /* end if */
+    else
+        if(plist2->del->root!=NULL) HGOTO_DONE (-1);
 
-        /* Check the actual properties */
-        while(tprop1!=NULL) {
-            /* Find a property with the same name in the second property list */
-            if((tprop2=H5P_find_prop(plist2->props,plist2->pclass->hashsize,tprop1->name))==NULL)
-                HGOTO_DONE(1);
+    /* Cycle through the changed properties and compare them also */
+    if(plist1->props->root) {
+        /* Check for no changed properties in plist2 */
+        if(plist2->props->root==NULL) HGOTO_DONE(1);
+
+        tnode1=H5TB_first(plist1->props->root);
+        tnode2=H5TB_first(plist2->props->root);
+        while(tnode1 || tnode2) {
+            /* Check if they both have properties in this TBBT node */
+            if(tnode1==NULL && tnode2!=NULL) HGOTO_DONE(-1);
+            if(tnode1!=NULL && tnode2==NULL) HGOTO_DONE(1);
 
             /* Compare the two properties */
-            if((cmp_value=H5P_cmp_prop(tprop1,tprop2))!=0)
+            if((cmp_value=H5P_cmp_prop(tnode1->data,tnode2->data))!=0)
                 HGOTO_DONE(cmp_value);
 
-            /* Advance to next property */
-            tprop1=tprop1->next;
+            /* Advance the pointers */
+            tnode1=H5TB_next(tnode1);
+            tnode2=H5TB_next(tnode2);
         } /* end while */
-    } /* end for */
+    } /* end if */
+    else
+        if(plist2->props->root!=NULL) HGOTO_DONE (-1);
+
+    /* Check the parent classes */
+    if((cmp_value=H5P_cmp_class(plist1->pclass,plist2->pclass))!=0)
+        HGOTO_DONE(cmp_value);
 
 done:
     FUNC_LEAVE (ret_value);
@@ -3099,7 +3454,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-htri_t H5Pequal(hid_t id1, hid_t id2)
+htri_t
+H5Pequal(hid_t id1, hid_t id2)
 {
     void *obj1, *obj2;          /* Property objects to compare */
     htri_t ret_value=FALSE;     /* return value */
@@ -3205,7 +3561,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-htri_t H5P_isa_class(hid_t plist_id, hid_t pclass_id)
+htri_t
+H5P_isa_class(hid_t plist_id, hid_t pclass_id)
 {
     H5P_genplist_t	*plist;         /* Property list to query */
     H5P_genclass_t	*pclass;        /* Property list class */
@@ -3251,7 +3608,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-htri_t H5Pisa_class(hid_t plist_id, hid_t pclass_id)
+htri_t
+H5Pisa_class(hid_t plist_id, hid_t pclass_id)
 {
     htri_t ret_value;                   /* return value */
 
@@ -3300,7 +3658,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-void *H5P_object_verify(hid_t plist_id, hid_t pclass_id)
+void *
+H5P_object_verify(hid_t plist_id, hid_t pclass_id)
 {
     void *ret_value;                   /* return value */
 
@@ -3321,100 +3680,6 @@ done:
 
 /*--------------------------------------------------------------------------
  NAME
-    H5P_iterate_props
- PURPOSE
-    Internal routine to iterate over a hashtable of properties 
- USAGE
-    herr_t H5P_iterate_props(id, hash, hashsize, idx, iter_func, iter_data)
-        hid_t id;                   IN: ID of property object iterating over
-        H5P_gen_prop_t *hash[];     IN: Pointer to array of properties for hash table
-        unsigned hashsize;             IN: Size of hash table
-        int *idx;                   IN/OUT: Index of the property to begin with
-        H5P_iterate_t iter_func;    IN: Function pointer to function to be
-                                        called with each property iterated over.
-        void *iter_data;            IN/OUT: Pointer to iteration data from user
- RETURNS
-    Success: Returns the return value of the last call to ITER_FUNC if it was
-                non-zero, or zero if all properties have been processed.
-    Failure: negative value
- DESCRIPTION
-    This routine iterates over the properties in the property object specified
-with ID.  For each property in the object, the ITER_DATA and some
-additional information, specified below, are passed to the ITER_FUNC function.
-The iteration begins with the IDX property in the object and the next element
-to be processed by the operator is returned in IDX.  If IDX is NULL, then the
-iterator starts at the first property; since no stopping point is returned in
-this case, the iterator cannot be restarted if one of the calls to its operator
-returns non-zero. 
-
-The prototype for H5P_iterate_t is: 
-    typedef herr_t (*H5P_iterate_t)(hid_t id, const char *name, void *iter_data); 
-The operation receives the property list or class identifier for the object
-being iterated over, ID, the name of the current property within the object,
-NAME, and the pointer to the operator data passed in to H5Piterate, ITER_DATA. 
-
-The return values from an operator are: 
-    Zero causes the iterator to continue, returning zero when all properties
-        have been processed. 
-    Positive causes the iterator to immediately return that positive value,
-        indicating short-circuit success. The iterator can be restarted at the
-        index of the next property. 
-    Negative causes the iterator to immediately return that value, indicating
-        failure. The iterator can be restarted at the index of the next
-        property.
-
-H5Piterate assumes that the properties in the object identified by ID remains
-unchanged through the iteration.  If the membership changes during the
-iteration, the function's behavior is undefined. 
-
- GLOBAL VARIABLES
- COMMENTS, BUGS, ASSUMPTIONS
- EXAMPLES
- REVISION LOG
---------------------------------------------------------------------------*/
-static int
-H5P_iterate_props(hid_t id, H5P_genprop_t *hash[], unsigned hashsize, int *idx, H5P_iterate_t iter_func, void *iter_data)
-{
-    H5P_genprop_t *prop;        /* Temporary property pointer */
-    unsigned u;                    /* Local index variable */
-    int curr_idx=0;             /* Current iteration index */
-    int ret_value=0;            /* Return value */
-
-    FUNC_ENTER_NOINIT(H5P_iterate_props);
-
-    assert(hash);
-    assert(hashsize>0);
-    assert(idx);
-    assert(iter_func);
-
-    /* Cycle through the properties and compare them also */
-    for(u=0; u<hashsize && ret_value==0; u++) {
-        prop=hash[u];
-
-        /* Check the actual properties */
-        while(prop!=NULL && ret_value==0) {
-            /* Check if we are at the object to start iterating over */
-            if(curr_idx>=*idx)
-                ret_value=(*iter_func)(id,prop->name,iter_data);
-
-            /* Increment the iteration index if iteration function succeeded */
-            if(ret_value==0)
-                curr_idx++;
-
-            /* Advance the pointer */
-            prop=prop->next;
-        } /* end while */
-    } /* end for */
-
-    /* Set the index we stopped at */
-    *idx=curr_idx;
-
-    FUNC_LEAVE (ret_value);
-}   /* H5P_iterate_props() */
-
-
-/*--------------------------------------------------------------------------
- NAME
     H5P_iterate_plist
  PURPOSE
     Internal routine to iterate over the properties in a property list
@@ -3467,8 +3732,13 @@ iteration, the function's behavior is undefined.
 static int
 H5P_iterate_plist(hid_t plist_id, int *idx, H5P_iterate_t iter_func, void *iter_data)
 {
+    H5P_genclass_t *tclass;     /* Temporary class pointer */
     H5P_genplist_t *plist;      /* Property list pointer */
-    int ret_value;              /* Return value */
+    H5P_genprop_t *tmp;         /* Temporary pointer to properties */
+    H5TB_TREE *seen=NULL;       /* TBBT to hold names of properties already seen */
+    H5TB_NODE *curr_node;       /* Current node in TBBT */
+    int curr_idx=0;             /* Current iteration index */
+    int ret_value=FAIL;         /* Return value */
 
     FUNC_ENTER_NOINIT(H5P_iterate_plist);
 
@@ -3479,10 +3749,90 @@ H5P_iterate_plist(hid_t plist_id, int *idx, H5P_iterate_t iter_func, void *iter_
     if (NULL == (plist = H5I_object_verify(plist_id, H5I_GENPROP_LST)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property list");
 
-    /* Iterate through the properties in the property list */
-    ret_value=H5P_iterate_props(plist_id, plist->props, plist->pclass->hashsize, idx, iter_func, iter_data);
+    /* Create the TBBT to hold names of properties already seen
+     */
+    if((seen=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,NULL,"can't create TBBT for seen properties");
+
+    /* Walk through the changed properties in the list */
+    if(plist->props->root) {
+        curr_node=H5TB_first(plist->props->root);
+        while(curr_node!=NULL) {
+            /* Get pointer to property from node */
+            tmp=curr_node->data;
+
+            /* Check if we've found the correctly indexed property */
+            if(curr_idx>=*idx) {
+                /* Call the callback function */
+                ret_value=(*iter_func)(plist_id,tmp->name,iter_data);
+
+                if(ret_value!=0)
+                    HGOTO_DONE(ret_value);
+            } /* end if */
+
+            /* Increment the current index */
+            curr_idx++;
+
+            /* Add property name to "seen" list */
+            if(H5TB_dins(seen,tmp->name,tmp->name)==NULL)
+                HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,NULL,"can't insert property into seen TBBT");
+
+            /* Get the next property node in the TBBT */
+            curr_node=H5TB_next(curr_node);
+        } /* end while */
+    } /* end if */
+
+    /* Walk up the class hiearchy */
+    tclass=plist->pclass;
+    while(tclass!=NULL) {
+        if(tclass->nprops>0) {
+            /* Walk through the properties in the class */
+            curr_node=H5TB_first(tclass->props->root);
+            while(curr_node!=NULL) {
+                /* Get pointer to property from node */
+                tmp=curr_node->data;
+
+                /* Only call iterator callback for properties we haven't seen
+                 * before and that haven't been deleted
+                 */
+                if(H5TB_dfind(seen,tmp->name,NULL)==NULL &&
+                        H5TB_dfind(plist->del,tmp->name,NULL)==NULL) {
+
+
+                    /* Check if we've found the correctly indexed property */
+                    if(curr_idx>=*idx) {
+                        /* Call the callback function */
+                        ret_value=(*iter_func)(plist_id,tmp->name,iter_data);
+
+                        if(ret_value!=0)
+                            HGOTO_DONE(ret_value);
+                    } /* end if */
+
+                    /* Increment the current index */
+                    curr_idx++;
+
+                    /* Add property name to "seen" list */
+                    if(H5TB_dins(seen,tmp->name,tmp->name)==NULL)
+                        HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,NULL,"can't insert property into seen TBBT");
+                } /* end if */
+
+                /* Get the next property node in the TBBT */
+                curr_node=H5TB_next(curr_node);
+            } /* end while */
+        } /* end if */
+
+        /* Go up to parent class */
+        tclass=tclass->parent;
+    } /* end while */
 
 done:
+    /* Set the index we stopped at */
+    *idx=curr_idx;
+
+    /* Release the tree of 'seen' properties */
+    if(seen!=NULL)
+        H5TB_dfree(seen,NULL,NULL);
+
     FUNC_LEAVE (ret_value);
 }   /* H5P_iterate_plist() */
 
@@ -3542,7 +3892,10 @@ static int
 H5P_iterate_pclass(hid_t pclass_id, int *idx, H5P_iterate_t iter_func, void *iter_data)
 {
     H5P_genclass_t *pclass;     /* Property list pointer */
-    int ret_value;              /* Return value */
+    H5TB_NODE *curr_node;       /* Current node in TBBT */
+    H5P_genprop_t *prop;        /* Temporary property pointer */
+    int curr_idx=0;             /* Current iteration index */
+    int ret_value=FAIL;         /* Return value */
 
     FUNC_ENTER_NOINIT(H5P_iterate_pclass);
 
@@ -3553,10 +3906,33 @@ H5P_iterate_pclass(hid_t pclass_id, int *idx, H5P_iterate_t iter_func, void *ite
     if (NULL == (pclass = H5I_object_verify(pclass_id, H5I_GENPROP_CLS)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a property class");
 
-    /* Iterate through the properties in the property list */
-    ret_value=H5P_iterate_props(pclass_id, pclass->props, pclass->hashsize, idx, iter_func, iter_data);
+    /* Set the current index */
+    curr_idx=*idx;
+
+    /* Cycle through the properties and call the callback */
+    curr_node=H5TB_index(pclass->props->root,(unsigned)*idx);
+    while(curr_node!=NULL) {
+        /* Get the property for the node */
+        prop=curr_node->data;
+
+        /* Call the callback function */
+        ret_value=(*iter_func)(pclass_id,prop->name,iter_data);
+
+        /* Check if iteration function succeeded */
+        if(ret_value!=0)
+            HGOTO_DONE(ret_value);
+
+        /* Increment the iteration index */
+        curr_idx++;
+
+        /* Get the next property node in the TBBT */
+        curr_node=H5TB_next(curr_node);
+    } /* end while */
 
 done:
+    /* Set the index we stopped at */
+    *idx=curr_idx;
+
     FUNC_LEAVE (ret_value);
 }   /* H5P_iterate_pclass() */
 
@@ -3613,7 +3989,8 @@ iteration, the function's behavior is undefined.
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-int H5Piterate(hid_t id, int *idx, H5P_iterate_t iter_func, void *iter_data)
+int
+H5Piterate(hid_t id, int *idx, H5P_iterate_t iter_func, void *iter_data)
 {
     int fake_idx=0;         /* Index when user doesn't provide one */
     int ret_value;          /* return value */
@@ -3672,7 +4049,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-unsigned H5P_peek_unsigned(H5P_genplist_t *plist, const char *name)
+unsigned
+H5P_peek_unsigned(H5P_genplist_t *plist, const char *name)
 {
     unsigned ret_value;            /* return value */
 
@@ -3716,7 +4094,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-hid_t H5P_peek_hid_t(H5P_genplist_t *plist, const char *name)
+hid_t
+H5P_peek_hid_t(H5P_genplist_t *plist, const char *name)
 {
     hid_t ret_value;            /* return value */
 
@@ -3760,7 +4139,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-void *H5P_peek_voidp(H5P_genplist_t *plist, const char *name)
+void *
+H5P_peek_voidp(H5P_genplist_t *plist, const char *name)
 {
     void * ret_value;            /* return value */
 
@@ -3804,7 +4184,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-hsize_t H5P_peek_hsize_t(H5P_genplist_t *plist, const char *name)
+hsize_t
+H5P_peek_hsize_t(H5P_genplist_t *plist, const char *name)
 {
     hsize_t ret_value;            /* return value */
 
@@ -3848,7 +4229,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-size_t H5P_peek_size_t(H5P_genplist_t *plist, const char *name)
+size_t
+H5P_peek_size_t(H5P_genplist_t *plist, const char *name)
 {
     size_t ret_value;            /* return value */
 
@@ -3893,9 +4275,12 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5P_get(H5P_genplist_t *plist, const char *name, void *value)
+herr_t
+H5P_get(H5P_genplist_t *plist, const char *name, void *value)
 {
+    H5P_genclass_t *tclass;     /* Temporary class pointer */
     H5P_genprop_t *prop;        /* Temporary property pointer */
+    H5TB_NODE *prop_node;       /* TBBT node holding property */
     herr_t      ret_value=SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOAPI(H5P_get, FAIL);
@@ -3904,36 +4289,113 @@ herr_t H5P_get(H5P_genplist_t *plist, const char *name, void *value)
     assert(name);
     assert(value);
 
-    /* Find property */
-    if((prop=H5P_find_prop(plist->props,plist->pclass->hashsize,name))==NULL)
+    /* Check if the property has been deleted */
+    if(H5TB_dfind(plist->del,name,NULL)!=NULL)
         HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "property doesn't exist");
 
-    /* Check for property size >0 */
-    if(prop->size==0)
-        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "property has zero size");
+    /* Find property */
+    if((prop_node=H5TB_dfind(plist->props,name,NULL))!=NULL) {
+        /* Get pointer to actual property */
+        prop=prop_node->data;
+
+        /* Check for property size >0 */
+        if(prop->size==0)
+            HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "property has zero size");
 
-    /* Make a copy of the value and pass to 'get' callback */
-    if(prop->get!=NULL) {
-        void *tmp_value;            /* Temporary value for property */
+        /* Make a copy of the value and pass to 'get' callback */
+        if(prop->get!=NULL) {
+            void *tmp_value;            /* Temporary value for property */
 
-        /* Make a copy of the current value, in case the callback fails */
-        if (NULL==(tmp_value=H5MM_malloc(prop->size)))
-            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed temporary property value");
-        HDmemcpy(tmp_value,prop->value,prop->size);
+            /* Make a copy of the current value, in case the callback fails */
+            if (NULL==(tmp_value=H5MM_malloc(prop->size)))
+                HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed temporary property value");
+            HDmemcpy(tmp_value,prop->value,prop->size);
 
-        /* Call user's callback */
-        if((*(prop->get))(plist->plist_id,name,prop->size,tmp_value)<0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't get property value");
+            /* Call user's callback */
+            if((*(prop->get))(plist->plist_id,name,prop->size,tmp_value)<0)
+                HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't get property value");
 
-        /* Copy new [possibly unchanged] value into return value */
-        HDmemcpy(value,tmp_value,prop->size);
+            /* Copy new [possibly unchanged] value into return value */
+            HDmemcpy(value,tmp_value,prop->size);
 
-        /* Free the temporary value buffer */
-        H5MM_xfree(tmp_value);
+            /* Free the temporary value buffer */
+            H5MM_xfree(tmp_value);
+        } /* end if */
+        /* No 'get' callback, just copy value */
+        else
+            HDmemcpy(value,prop->value,prop->size);
     } /* end if */
-    /* No 'get' callback, just copy value */
-    else
-        HDmemcpy(value,prop->value,prop->size);
+    else {
+        /*
+         * Check if we should get class properties (up through list of parent classes also),
+         * & make property 'get' callback.
+         */
+        tclass=plist->pclass;
+        while(tclass!=NULL) {
+            if(tclass->nprops>0) {
+                /* Find the property in the class */
+                if((prop_node=H5TB_dfind(tclass->props,name,NULL))!=NULL) {
+                    /* Get pointer to actual property */
+                    prop=prop_node->data;
+
+                    /* Check for property size >0 */
+                    if(prop->size==0)
+                        HGOTO_ERROR(H5E_PLIST,H5E_BADVALUE,FAIL,"property has zero size");
+
+                    /* Call the 'get' callback, if there is one */
+                    if(prop->get!=NULL) {
+                        void *tmp_value;            /* Temporary value for property */
+
+                        /* Make a copy of the current value, in case the callback fails */
+                        if (NULL==(tmp_value=H5MM_malloc(prop->size)))
+                            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed temporary property value");
+                        HDmemcpy(tmp_value,prop->value,prop->size);
+
+                        /* Call user's callback */
+                        if((*(prop->get))(plist->plist_id,name,prop->size,tmp_value)<0) {
+                            H5MM_xfree(tmp_value);
+                            HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't set property value");
+                        } /* end if */
+
+                        if(HDmemcmp(tmp_value,prop->value,prop->size)) {
+                            H5P_genprop_t *pcopy;  /* Copy of property to insert into TBBT */
+
+                            /* Make a copy of the class's property */
+                            if((pcopy=H5P_dup_prop(prop,H5P_PROP_WITHIN_LIST))==NULL)
+                                HGOTO_ERROR(H5E_PLIST,H5E_CANTCOPY,FAIL,"Can't copy property");
+
+                            /* Copy new value into property value */
+                            HDmemcpy(pcopy->value,tmp_value,prop->size);
+
+                            /* Insert the changed property into the property list */
+                            if(H5P_add_prop(plist->props,pcopy)<0)
+                                HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, FAIL,"Can't insert changed property into TBBT");
+                        } /* end if */
+
+                        /* Copy new [possibly unchanged] value into return value */
+                        HDmemcpy(value,tmp_value,prop->size);
+
+                        /* Free the temporary value buffer */
+                        H5MM_xfree(tmp_value);
+                    } /* end if */
+                    /* No 'get' callback, just copy value */
+                    else
+                        HDmemcpy(value,prop->value,prop->size);
+
+                    /* Leave */
+                    HGOTO_DONE(SUCCEED);
+                } /* end while */
+            } /* end if */
+
+            /* Go up to parent class */
+            tclass=tclass->parent;
+        } /* end while */
+
+        /* If we get this far, then it wasn't in the list of changed properties,
+         * nor in the properties in the class hierarchy, indicate an error
+         */
+        HGOTO_ERROR(H5E_PLIST,H5E_NOTFOUND,FAIL,"can't find property in TBBT");
+    } /* end else */
 
 done:
     FUNC_LEAVE (ret_value);
@@ -3968,7 +4430,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5Pget(hid_t plist_id, const char *name, void * value)
+herr_t
+H5Pget(hid_t plist_id, const char *name, void * value)
 {
     H5P_genplist_t *plist;      /* Property list pointer */
     herr_t ret_value=SUCCEED;   /* return value */
@@ -4021,63 +4484,106 @@ done:
 herr_t
 H5P_remove(hid_t plist_id, H5P_genplist_t *plist, const char *name)
 {
+    H5P_genclass_t *tclass;     /* Temporary class pointer */
+    H5TB_NODE *curr_node;       /* TBBT node holding property */
     H5P_genprop_t *prop;        /* Temporary property pointer */
-    H5P_genprop_t *tprop, *prev;/* Temporary pointer to properties */
-    unsigned loc;                  /* Hash table location */
-    herr_t      ret_value=SUCCEED;       /* Return value */
+    char *del_name;             /* Pointer to deleted name */
+    herr_t ret_value=SUCCEED;   /* Return value */
 
-    FUNC_ENTER_NOINIT(H5P_remove);
+    FUNC_ENTER_NOAPI(H5P_remove,FAIL);
 
     assert(plist);
     assert(name);
 
-    /* Find the property in the property list */
-    if((prop=H5P_find_prop(plist->props,plist->pclass->hashsize,name))==NULL)
-        HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "property doesn't exist");
+    /* Indicate that the property isn't in the list if it has been deleted already */
+    if(H5TB_dfind(plist->del,name,NULL)!=NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_NOTFOUND,FAIL,"can't find property in TBBT");
 
-    /* Pass value to 'close' callback, if it exists */
-    if(prop->del!=NULL) {
-        /* Call user's callback */
-        if((*(prop->del))(plist_id,name,prop->size,prop->value)<0)
-            HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't close property value");
-    } /* end if */
+    /* Get the property node from the changed property TBBT */
+    if((curr_node=H5TB_dfind(plist->props,name,NULL))!=NULL) {
+        /* Get pointer to property for node */
+        prop=curr_node->data;
 
-    /* Get correct hash table location */
-    loc=H5P_hash_name(name,plist->pclass->hashsize);
-    
-    /* Remove property from property list */
-    /* Check if the property being removed is at the head of the list for a hash location */
-    if(prop==plist->props[loc]) {
-        /* Jump over the property we are deleting */
-        plist->props[loc]=prop->next;
+        /* Pass value to 'close' callback, if it exists */
+        if(prop->del!=NULL) {
+            /* Call user's callback */
+            if((*(prop->del))(plist_id,name,prop->size,prop->value)<0)
+                HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't close property value");
+        } /* end if */
+
+        /* Duplicate string for insertion into new deleted property TBBT */
+        if((del_name=H5MM_xstrdup(name))==NULL)
+            HGOTO_ERROR(H5E_RESOURCE,H5E_NOSPACE,FAIL,"memory allocation failed");
+
+        /* Insert property name into deleted list */
+        if(H5TB_dins(plist->del,del_name,del_name)==NULL)
+            HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,FAIL,"can't insert property into deleted TBBT");
+
+        /* Remove the property from the TBBT */
+        if(H5TB_rem(&plist->props->root,curr_node,NULL)==NULL)
+            HGOTO_ERROR(H5E_PLIST,H5E_CANTDELETE,FAIL,"can't remove property from TBBT");
 
         /* Free the property, ignoring return value, nothing we can do */
         H5P_free_prop(prop);
+
+        /* Decrement the number of properties in list */
+        plist->nprops--;
     } /* end if */
+    /* Walk through all the properties in the class hierarchy, looking for the property */
     else {
-        /* Set up initial pointers */
-        prev=tprop=plist->props[loc];
-        tprop=tprop->next;
-        while(tprop!=NULL) {
-            if(tprop==prop) {
-                /* Jump over the property we are deleting */
-                prev->next=prop->next;
-
-                /* Free the property, ignoring return value, nothing we can do */
-                H5P_free_prop(prop);
-
-                /* Break out of while loop */
-                break;
+        /*
+         * Check if we should delete class properties (up through list of parent classes also),
+         * & make property 'delete' callback.
+         */
+        tclass=plist->pclass;
+        while(tclass!=NULL) {
+            if(tclass->nprops>0) {
+                /* Find the property in the class */
+                if((prop=H5P_find_prop_pclass(tclass,name))!=NULL) {
+                    /* Pass value to 'del' callback, if it exists */
+                    if(prop->del!=NULL) {
+                        void *tmp_value;       /* Temporary value buffer */
+
+                        /* Allocate space for a temporary copy of the property value */
+                        if (NULL==(tmp_value=H5MM_malloc(prop->size)))
+                            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for temporary property value");
+                        HDmemcpy(tmp_value,prop->value,prop->size);
+
+                        /* Call user's callback */
+                        if((*(prop->del))(plist_id,name,prop->size,tmp_value)<0) {
+                            H5MM_xfree(tmp_value);
+                            HGOTO_ERROR(H5E_PLIST, H5E_CANTINIT, FAIL, "can't close property value");
+                        } /* end if */
+
+                        /* Release the temporary value buffer */
+                        H5MM_xfree(tmp_value);
+                    } /* end if */
+
+                    /* Duplicate string for insertion into new deleted property TBBT */
+                    if((del_name=H5MM_xstrdup(name))==NULL)
+                        HGOTO_ERROR(H5E_RESOURCE,H5E_NOSPACE,FAIL,"memory allocation failed");
+
+                    /* Insert property name into deleted list */
+                    if(H5TB_dins(plist->del,del_name,del_name)==NULL)
+                        HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,FAIL,"can't insert property into deleted TBBT");
+
+                    /* Decrement the number of properties in list */
+                    plist->nprops--;
+
+                    /* Leave */
+                    HGOTO_DONE(SUCCEED);
+                } /* end while */
             } /* end if */
 
-            /* Move to the next nodes */
-            prev=tprop;
-            tprop=tprop->next;
+            /* Go up to parent class */
+            tclass=tclass->parent;
         } /* end while */
-    } /* end else */
 
-    /* Decrement the number of properties in list */
-    plist->nprops--;
+        /* If we get this far, then it wasn't in the list of changed properties,
+         * nor in the properties in the class hierarchy, indicate an error
+         */
+        HGOTO_ERROR(H5E_PLIST,H5E_NOTFOUND,FAIL,"can't find property in TBBT");
+    } /* end else */
 
 done:
     FUNC_LEAVE (ret_value);
@@ -4110,7 +4616,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5Premove(hid_t plist_id, const char *name)
+herr_t
+H5Premove(hid_t plist_id, const char *name)
 {
     H5P_genplist_t	*plist;    /* Property list to modify */
     herr_t ret_value;           /* return value */
@@ -4180,20 +4687,17 @@ H5P_copy_prop_plist(hid_t dst_id, hid_t src_id, const char *name)
     if(NULL == (src_plist = H5I_object(src_id)) || NULL == (dst_plist = H5I_object(dst_id)))
         HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "property object doesn't exist");
 
-    /* Check if the property exists in the destination */
-    prop=H5P_find_prop(dst_plist->props,dst_plist->pclass->hashsize,name);
-
     /* If the property exists in the destination alread */
-    if(prop!=NULL) {
+    if(H5P_find_prop_plist(dst_plist,name)!=NULL) {
         /* Delete the property from the destination list, calling the 'close' callback if necessary */
         if(H5P_remove(dst_id,dst_plist,name)<0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTDELETE, FAIL, "unable to remove property");
 
         /* Get the pointer to the source property */
-        prop=H5P_find_prop(src_plist->props,src_plist->pclass->hashsize,name);
+        prop=H5P_find_prop_plist(src_plist,name);
 
         /* Make a copy of the source property */
-        if((new_prop=H5P_dup_prop(prop))==NULL)
+        if((new_prop=H5P_dup_prop(prop,H5P_PROP_WITHIN_LIST))==NULL)
             HGOTO_ERROR (H5E_PLIST, H5E_CANTCOPY, FAIL,"Can't copy property");
 
         /* Call property copy callback, if it exists */
@@ -4203,7 +4707,7 @@ H5P_copy_prop_plist(hid_t dst_id, hid_t src_id, const char *name)
         } /* end if */
 
         /* Insert the initialized property into the property list */
-        if(H5P_add_prop(dst_plist->props,dst_plist->pclass->hashsize,new_prop)<0)
+        if(H5P_add_prop(dst_plist->props,new_prop)<0)
             HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, FAIL,"Can't insert property into list");
 
         /* Increment the number of properties in list */
@@ -4212,10 +4716,10 @@ H5P_copy_prop_plist(hid_t dst_id, hid_t src_id, const char *name)
     /* If not, get the information required to do an H5Pinsert with the property into the destination list */
     else {
         /* Get the pointer to the source property */
-        prop=H5P_find_prop(src_plist->props,src_plist->pclass->hashsize,name);
+        prop=H5P_find_prop_plist(src_plist,name);
 
         /* Create property object from parameters */
-        if((new_prop=H5P_create_prop(prop->name,prop->size,prop->def_value,prop->value,prop->create,prop->set,prop->get,prop->del,prop->copy,prop->copy))==NULL)
+        if((new_prop=H5P_create_prop(prop->name,prop->size,H5P_PROP_WITHIN_LIST,prop->value,prop->create,prop->set,prop->get,prop->del,prop->copy,prop->copy))==NULL)
             HGOTO_ERROR (H5E_PLIST, H5E_CANTCREATE, FAIL,"Can't create property");
 
         /* Call property creation callback, if it exists */
@@ -4225,7 +4729,7 @@ H5P_copy_prop_plist(hid_t dst_id, hid_t src_id, const char *name)
         } /* end if */
 
         /* Insert property into property list class */
-        if(H5P_add_prop(dst_plist->props,dst_plist->pclass->hashsize,new_prop)<0)
+        if(H5P_add_prop(dst_plist->props,new_prop)<0)
             HGOTO_ERROR (H5E_PLIST, H5E_CANTINSERT, FAIL,"Can't insert property into class");
 
         /* Increment property count for class */
@@ -4274,7 +4778,7 @@ done:
  REVISION LOG
 --------------------------------------------------------------------------*/
 static herr_t
-H5P_copy_prop_pclass(H5P_genclass_t *dst_pclass, H5P_genclass_t UNUSED *src_pclass, const char *name)
+H5P_copy_prop_pclass(H5P_genclass_t *dst_pclass, H5P_genclass_t *src_pclass, const char *name)
 {
     H5P_genprop_t *prop;            /* Temporary property pointer */
     herr_t ret_value=SUCCEED;       /* return value */
@@ -4285,18 +4789,19 @@ H5P_copy_prop_pclass(H5P_genclass_t *dst_pclass, H5P_genclass_t UNUSED *src_pcla
     assert(src_pclass);
     assert(name);
 
-    /* Check if the property exists in the destination */
-    prop=H5P_find_prop(dst_pclass->props,dst_pclass->hashsize,name);
-
     /* If the property exists in the destination already */
-    if(prop!=NULL) {
+    if(H5P_exist_pclass(dst_pclass,name)) {
         /* Delete the old property from the destination class */
         if(H5P_unregister(dst_pclass,name)<0)
             HGOTO_ERROR(H5E_PLIST, H5E_CANTDELETE, FAIL, "unable to remove property");
     } /* end if */
 
+    /* Get the property from the source */
+    if((prop=H5P_find_prop_pclass(src_pclass,name))==NULL)
+        HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "unable to locate property");
+
     /* Register the property into the destination */
-    if(H5P_register(dst_pclass,name,prop->size,prop->def_value,prop->create,prop->set,prop->get,prop->del,prop->copy,prop->close)<0)
+    if(H5P_register(dst_pclass,name,prop->size,prop->value,prop->create,prop->set,prop->get,prop->del,prop->copy,prop->close)<0)
         HGOTO_ERROR(H5E_PLIST, H5E_CANTDELETE, FAIL, "unable to remove property");
 
 done:
@@ -4404,9 +4909,8 @@ done:
 static herr_t
 H5P_unregister(H5P_genclass_t *pclass, const char *name)
 {
+    H5TB_NODE *prop_node;       /* TBBT node holding property */
     H5P_genprop_t *prop;        /* Temporary property pointer */
-    H5P_genprop_t *tprop, *prev;/* Temporary pointer to properties */
-    unsigned loc;                  /* Hash table location */
     herr_t      ret_value=SUCCEED;       /* Return value */
 
     FUNC_ENTER_NOINIT(H5P_unregister);
@@ -4414,46 +4918,26 @@ H5P_unregister(H5P_genclass_t *pclass, const char *name)
     assert(pclass);
     assert(name);
 
-    /* Find the property in the property list */
-    if((prop=H5P_find_prop(pclass->props,pclass->hashsize,name))==NULL)
-        HGOTO_ERROR(H5E_PLIST, H5E_NOTFOUND, FAIL, "property doesn't exist");
+    /* Get the property node from the TBBT */
+    if((prop_node=H5TB_dfind(pclass->props,name,NULL))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_NOTFOUND,NULL,"can't find property in TBBT");
 
-    /* Get correct hash table location */
-    loc=H5P_hash_name(name,pclass->hashsize);
-    
-    /* Remove property from property list */
-    /* Check if the property being removed is at the head of the list for a hash location */
-    if(prop==pclass->props[loc]) {
-        pclass->props[loc]=prop->next;
+    /* Get the pointer to the property */
+    prop=prop_node->data;
 
-        /* Free the property, ignoring return value, nothing we can do */
-        H5P_free_prop(prop);
-    } /* end if */
-    else {
-        /* Set up initial pointers */
-        prev=tprop=pclass->props[loc];
-        tprop=tprop->next;
-        while(tprop!=NULL) {
-            if(tprop==prop) {
-                /* Jump over the property we are deleting */
-                prev->next=prop->next;
-
-                /* Free the property, ignoring return value, nothing we can do */
-                H5P_free_prop(prop);
-
-                /* Break out of while loop */
-                break;
-            } /* end if */
+    /* Remove the property from the TBBT */
+    if(H5TB_rem(&pclass->props->root,prop_node,NULL)==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTDELETE,FAIL,"can't remove property from TBBT");
 
-            /* Move to the next nodes */
-            prev=tprop;
-            tprop=tprop->next;
-        } /* end while */
-    } /* end else */
+    /* Free the property, ignoring return value, nothing we can do */
+    H5P_free_prop(prop);
 
     /* Decrement the number of registered properties in class */
     pclass->nprops--;
 
+    /* Update the revision for the class */
+    pclass->revision = H5P_GET_NEXT_REV;
+
 done:
     FUNC_LEAVE (ret_value);
 }   /* H5P_unregister() */
@@ -4480,7 +4964,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5Punregister(hid_t pclass_id, const char *name)
+herr_t
+H5Punregister(hid_t pclass_id, const char *name)
 {
     H5P_genclass_t	*pclass;   /* Property list class to modify */
     herr_t ret_value;           /* return value */
@@ -4529,8 +5014,12 @@ done:
 herr_t
 H5P_close(void *_plist)
 {
+    H5P_genclass_t *tclass;         /* Temporary class pointer */
     H5P_genplist_t *plist=(H5P_genplist_t *)_plist;
-    herr_t ret_value=SUCCEED;     /* return value */
+    H5TB_TREE *seen=NULL;           /* TBBT to hold names of properties already seen */
+    H5TB_NODE *curr_node;           /* Current node in TBBT */
+    H5P_genprop_t *tmp;             /* Temporary pointer to properties */
+    herr_t ret_value=SUCCEED;       /* return value */
 
     FUNC_ENTER_NOINIT(H5P_close);
 
@@ -4542,17 +5031,106 @@ H5P_close(void *_plist)
         (plist->pclass->close_func)(plist->plist_id,plist->pclass->close_data);
     } /* end if */
 
-    /* Make calls to any property close callbacks which exist */
-    H5P_free_all_prop(plist->props,plist->pclass->hashsize,1);
+    /* Create the TBBT to hold names of properties already seen
+     * (This prevents a property in the class hierarchy from having it's
+     * 'close' callback called, if a property in the class hierarchy has
+     * already been seen)
+     */
+    if((seen=H5TB_fast_dmake(H5TB_FAST_STR_COMPARE))==NULL)
+        HGOTO_ERROR(H5E_PLIST,H5E_CANTMAKETREE,NULL,"can't create TBBT for seen properties");
+
+    /* Walk through the changed properties in the list */
+    if(plist->props->root) {
+        curr_node=H5TB_first(plist->props->root);
+        while(curr_node!=NULL) {
+            /* Get pointer to property from node */
+            tmp=curr_node->data;
+
+            /* Call property close callback, if it exists */
+            if(tmp->close) {
+                /* Call the 'close' callback */
+                (tmp->close)(tmp->name,tmp->size,tmp->value);
+            } /* end if */
+
+            /* Add property name to "seen" list */
+            if(H5TB_dins(seen,tmp->name,tmp->name)==NULL)
+                HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,NULL,"can't insert property into seen TBBT");
+
+            /* Get the next property node in the TBBT */
+            curr_node=H5TB_next(curr_node);
+        } /* end while */
+    } /* end if */
+
+    /*
+     * Check if we should remove class properties (up through list of parent classes also),
+     * initialize each with default value & make property 'remove' callback.
+     */
+    tclass=plist->pclass;
+    while(tclass!=NULL) {
+        if(tclass->nprops>0) {
+            /* Walk through the properties in the class */
+            curr_node=H5TB_first(tclass->props->root);
+            while(curr_node!=NULL) {
+                /* Get pointer to property from node */
+                tmp=curr_node->data;
+
+                /* Only "delete" properties we haven't seen before
+                 * and that haven't already been deleted
+                 */
+                if(H5TB_dfind(seen,tmp->name,NULL)==NULL &&
+                        H5TB_dfind(plist->del,tmp->name,NULL)==NULL) {
+
+                    /* Call property close callback, if it exists */
+                    if(tmp->close) {
+                        void *tmp_value;       /* Temporary value buffer */
+
+                        /* Allocate space for a temporary copy of the property value */
+                        if (NULL==(tmp_value=H5MM_malloc(tmp->size)))
+                            HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for temporary property value");
+                        HDmemcpy(tmp_value,tmp->value,tmp->size);
+
+                        /* Call the 'close' callback */
+                        (tmp->close)(tmp->name,tmp->size,tmp_value);
+
+                        /* Release the temporary value buffer */
+                        H5MM_xfree(tmp_value);
+                    } /* end if */
+
+                    /* Add property name to "seen" list */
+                    if(H5TB_dins(seen,tmp->name,tmp->name)==NULL)
+                        HGOTO_ERROR(H5E_PLIST,H5E_CANTINSERT,NULL,"can't insert property into seen TBBT");
+                } /* end if */
+
+                /* Get the next property node in the TBBT */
+                curr_node=H5TB_next(curr_node);
+            } /* end while */
+        } /* end if */
+
+        /* Go up to parent class */
+        tclass=tclass->parent;
+    } /* end while */
 
     /* Decrement class's dependant property list value! */
     if(H5P_access_class(plist->pclass,H5P_MOD_DEC_LST)<0)
         HGOTO_ERROR (H5E_PLIST, H5E_CANTINIT, FAIL, "Can't decrement class ref count");
 
+    /* Free the list of 'seen' properties */
+    seen=H5TB_dfree(seen,NULL,NULL);
+
+    /* Free the list of deleted property names */
+    H5TB_dfree(plist->del,free,NULL);
+
+    /* Free the property tree itself */
+    H5TB_dfree(plist->props,H5P_free_prop,NULL);
+
     /* Destroy property list object */
-    H5MM_xfree(plist);
+    H5FL_FREE(H5P_genplist_t,plist);
 
 done:
+    /* Release the tree of 'seen' properties */
+    if(seen!=NULL)
+        H5TB_dfree(seen,NULL,NULL);
+
     FUNC_LEAVE (ret_value);
 }   /* H5P_close() */
 
@@ -4578,7 +5156,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-herr_t H5Pclose(hid_t plist_id)
+herr_t
+H5Pclose(hid_t plist_id)
 {
     H5P_genplist_t	*plist;    /* Property list created */
     herr_t ret_value=SUCCEED;      /* return value */
@@ -4625,7 +5204,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-char *H5P_get_class_name(H5P_genclass_t *pclass)
+char *
+H5P_get_class_name(H5P_genclass_t *pclass)
 {
     char *ret_value;      /* return value */
 
@@ -4661,7 +5241,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-char *H5Pget_class_name(hid_t pclass_id)
+char *
+H5Pget_class_name(hid_t pclass_id)
 {
     H5P_genclass_t	*pclass;    /* Property class to query */
     char *ret_value;       /* return value */
@@ -4889,7 +5470,8 @@ done:
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-hid_t H5P_open_class_path_test(const char *path)
+hid_t
+H5P_open_class_path_test(const char *path)
 {
     H5P_genclass_t *pclass=NULL;/* Property class to query */
     hid_t ret_value;            /* Return value */
@@ -4970,7 +5552,8 @@ H5P_get_class_parent(H5P_genclass_t *pclass)
  EXAMPLES
  REVISION LOG
 --------------------------------------------------------------------------*/
-hid_t H5Pget_class_parent(hid_t pclass_id)
+hid_t
+H5Pget_class_parent(hid_t pclass_id)
 {
     H5P_genclass_t	*pclass;    /* Property class to query */
     H5P_genclass_t	*parent=NULL;   /* Parent's property class */
diff --git a/src/H5Pdcpl.c b/src/H5Pdcpl.c
index c034156..92ebfc2 100644
--- a/src/H5Pdcpl.c
+++ b/src/H5Pdcpl.c
@@ -963,7 +963,7 @@ H5Pget_fill_value(hid_t plist_id, hid_t type_id, void *value/*out*/)
     HDmemcpy(buf, fill.buf, H5T_get_size(fill.type));
         
     /* Do the conversion */
-    if (H5T_convert(tpath, src_id, type_id, (hsize_t)1, 0, 0, buf, bkg, H5P_DEFAULT)<0)
+    if (H5T_convert(tpath, src_id, type_id, (hsize_t)1, 0, 0, buf, bkg, H5P_DATASET_XFER_DEFAULT)<0)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "data type conversion failed");
     if (buf!=value)
         HDmemcpy(value, buf, H5T_get_size(type));
@@ -980,7 +980,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5P_fill_value_defined
+ * Function:    H5P_is_fill_value_defined
  *
  * Purpose:	Check if fill value is defined.  Internal version of function
  * 
@@ -990,35 +990,30 @@ done:
  *              Wednesday, January 16, 2002
  *
  * Modifications:
- *              
+ *              Extracted from H5P_fill_value_defined, QAK, Dec. 13, 2002
  *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5P_fill_value_defined(H5P_genplist_t *plist, H5D_fill_value_t *status)
+H5P_is_fill_value_defined(const struct H5O_fill_t *fill, H5D_fill_value_t *status)
 {
     herr_t		ret_value = SUCCEED;
-    H5O_fill_t		fill;
 
-    FUNC_ENTER_NOAPI(H5P_fill_value_defined, FAIL);
+    FUNC_ENTER_NOAPI(H5P_is_fill_value_defined, FAIL);
 
-    assert(plist);
+    assert(fill);
     assert(status);
 
-    /* Get the fill value struct */
-    if(H5P_get(plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get fill value"); 
-
     /* Check if the fill value was never set */
-    if(fill.size == (size_t)-1 && !fill.buf) {
+    if(fill->size == (size_t)-1 && !fill->buf) {
 	*status = H5D_FILL_VALUE_UNDEFINED;
     }
     /* Check if the fill value was set to the default fill value by the library */
-    else if(fill.size == 0 && !fill.buf) {
+    else if(fill->size == 0 && !fill->buf) {
 	*status = H5D_FILL_VALUE_DEFAULT;
     }
     /* Check if the fill value was set by the application */
-    else if(fill.size > 0 && fill.buf) {
+    else if(fill->size > 0 && fill->buf) {
 	*status = H5D_FILL_VALUE_USER_DEFINED;
     }
     else {
@@ -1028,6 +1023,45 @@ H5P_fill_value_defined(H5P_genplist_t *plist, H5D_fill_value_t *status)
 
 done:
     FUNC_LEAVE(ret_value);
+} /* end H5P_is_fill_value_defined() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5P_fill_value_defined
+ *
+ * Purpose:	Check if fill value is defined.  Internal version of function
+ * 
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:  Raymond Lu
+ *              Wednesday, January 16, 2002
+ *
+ * Modifications:
+ *              
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5P_fill_value_defined(H5P_genplist_t *plist, H5D_fill_value_t *status)
+{
+    herr_t		ret_value = SUCCEED;
+    H5O_fill_t		fill;
+
+    FUNC_ENTER_NOAPI(H5P_fill_value_defined, FAIL);
+
+    assert(plist);
+    assert(status);
+
+    /* Get the fill value struct */
+    if(H5P_get(plist, H5D_CRT_FILL_VALUE_NAME, &fill) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get fill value"); 
+
+    /* Get the fill-value status */
+    if(H5P_is_fill_value_defined(&fill, status) < 0)
+        HGOTO_ERROR(H5E_PLIST, H5E_BADVALUE, FAIL, "can't check fill value status"); 
+
+done:
+    FUNC_LEAVE(ret_value);
 } /* end H5P_fill_value_defined() */
 
 
diff --git a/src/H5Pfapl.c b/src/H5Pfapl.c
index 2e32e0a..ba4be48 100644
--- a/src/H5Pfapl.c
+++ b/src/H5Pfapl.c
@@ -526,7 +526,7 @@ herr_t H5Pset_family_offset(hid_t fapl_id, hsize_t offset)
 
     /* Get the plist structure */
     if(H5P_DEFAULT == fapl_id)
-         fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "can't modify default property list");
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
          HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
     /* Set values */
@@ -600,7 +600,7 @@ herr_t H5Pget_family_offset(hid_t fapl_id, hsize_t *offset)
                                             
     /* Get the plist structure */
     if(H5P_DEFAULT == fapl_id)
-         fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "can't modify default property list");
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
          HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
     /* Set values */
@@ -674,7 +674,7 @@ herr_t H5Pset_multi_type(hid_t fapl_id, H5FD_mem_t type)
 
     /* Get the plist structure */
     if(H5P_DEFAULT == fapl_id)
-         fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "can't modify default property list");
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
          HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
     /* Set values */
@@ -748,7 +748,7 @@ herr_t H5Pget_multi_type(hid_t fapl_id, H5FD_mem_t *type)
                                         
     /* Get the plist structure */
     if(H5P_DEFAULT == fapl_id)
-         fapl_id = H5Pcreate(H5P_FILE_ACCESS);
+        HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "can't modify default property list");
     if(NULL == (plist = H5P_object_verify(fapl_id,H5P_FILE_ACCESS)))
          HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "can't find object for ID");
     /* Set values */
diff --git a/src/H5Ppkg.h b/src/H5Ppkg.h
index b600769..65b76a0 100644
--- a/src/H5Ppkg.h
+++ b/src/H5Ppkg.h
@@ -24,6 +24,14 @@
 #endif
 
 #include "H5Pprivate.h"
+#include "H5TBprivate.h"	/* TBBTs	  		        */
+
+/* Define enum for type of object that property is within */
+typedef enum {
+    H5P_PROP_WITHIN_UNKNOWN=0,  /* Property container is unknown */
+    H5P_PROP_WITHIN_LIST,       /* Property is within a list */
+    H5P_PROP_WITHIN_CLASS       /* Property is within a class */
+} H5P_prop_within_t;
 
 /* Define enum for modifications to class */
 typedef enum {
@@ -40,21 +48,19 @@ typedef enum {
 /* Define structure to hold property information */
 typedef struct H5P_genprop_t {
     /* Values for this property */
-    unsigned xor_val;      /* XOR'ed version of the name, for faster comparisons */
     char *name;         /* Name of property */
     size_t size;        /* Size of property value */
     void *value;        /* Pointer to property value */
+    H5P_prop_within_t type;     /* Type of object the property is within */
+    unsigned shared_name;       /* Boolean: whether the name is shared or not */
 
     /* Callback function pointers & info */
     H5P_prp_create_func_t create;   /* Function to call when a property is created */
-    void *def_value;      /* Pointer to default value to pass along to create callback */
     H5P_prp_set_func_t set; /* Function to call when a property value is set */
     H5P_prp_get_func_t get; /* Function to call when a property value is retrieved */
     H5P_prp_delete_func_t del; /* Function to call when a property is deleted */
     H5P_prp_copy_func_t copy;  /* Function to call when a property is copied */
     H5P_prp_close_func_t close; /* Function to call when a property is closed */
-
-    struct H5P_genprop_t *next;  /* Pointer to the next property in this list */
 } H5P_genprop_t;
 
 /* Define structure to hold class information */
@@ -62,12 +68,13 @@ struct H5P_genclass_t {
     struct H5P_genclass_t *parent;     /* Pointer to parent class */
     char *name;         /* Name of property list class */
     size_t  nprops;     /* Number of properties in class */
-    unsigned   hashsize;   /* Hash table size */
     unsigned   plists;     /* Number of property lists that have been created since the last modification to the class */
     unsigned   classes;    /* Number of classes that have been derived since the last modification to the class */
     unsigned   ref_count;  /* Number of oustanding ID's open on this class object */
     unsigned   internal;   /* Whether this class is internal to the library or not */
     unsigned   deleted;    /* Whether this class has been deleted and is waiting for dependent classes & proplists to close */
+    unsigned   revision;   /* Revision number of a particular class (global) */
+    H5TB_TREE *props;   /* TBBT containing properties */
 
     /* Callback function pointers & info */
     H5P_cls_create_func_t create_func;  /* Function to call when a property list is created */
@@ -76,8 +83,6 @@ struct H5P_genclass_t {
     void *copy_data;    /* Pointer to user data to pass along to copy callback */
     H5P_cls_close_func_t close_func;   /* Function to call when a property list is closed */
     void *close_data;   /* Pointer to user data to pass along to close callback */
-
-    H5P_genprop_t *props[1];  /* Hash table of pointers to properties in the class */
 };
 
 /* Define structure to hold property list information */
@@ -86,14 +91,14 @@ struct H5P_genplist_t {
     hid_t   plist_id;       /* Copy of the property list ID (for use in close callback) */
     size_t  nprops;         /* Number of properties in class */
     unsigned   class_init:1;   /* Whether the class initialization callback finished successfully */
-
-    /* Hash size for a property list is same as class */
-    H5P_genprop_t *props[1];  /* Hash table of pointers to properties in the list */
+    H5TB_TREE *del;     /* TBBT containing names of deleted properties */
+    H5TB_TREE *props;   /* TBBT containing properties */
 };
 
 /* Private functions, not part of the publicly documented API */
-H5_DLL herr_t H5P_add_prop(H5P_genprop_t *hash[], unsigned hashsize, H5P_genprop_t *prop);
+H5_DLL herr_t H5P_add_prop(H5TB_TREE *props, H5P_genprop_t *prop);
 H5_DLL herr_t H5P_access_class(H5P_genclass_t *pclass, H5P_class_mod_t mod);
+H5_DLL int H5P_tbbt_strcmp(const void *k1, const void *k2, int UNUSED cmparg);
 
 #endif /* _H5Ppkg_H */
 
diff --git a/src/H5Pprivate.h b/src/H5Pprivate.h
index dca48be..d854936 100644
--- a/src/H5Pprivate.h
+++ b/src/H5Pprivate.h
@@ -25,6 +25,9 @@
 typedef struct H5P_genplist_t H5P_genplist_t;
 typedef struct H5P_genclass_t H5P_genclass_t;
 
+/* Forward declarations for prototypes arguments */
+struct H5O_fill_t;
+
 /* Private functions, not part of the publicly documented API */
 H5_DLL herr_t H5P_init(void);
 
@@ -60,6 +63,8 @@ H5_DLL herr_t H5P_get_multi_type(H5P_genplist_t *plist, H5FD_mem_t *type);
 H5_DLL herr_t H5P_set_vlen_mem_manager(H5P_genplist_t *plist,
         H5MM_allocate_t alloc_func, void *alloc_info, H5MM_free_t free_func,
         void *free_info);
+H5_DLL herr_t H5P_is_fill_value_defined(const struct H5O_fill_t *fill,
+        H5D_fill_value_t *status);
 H5_DLL herr_t H5P_fill_value_defined(H5P_genplist_t *plist,
         H5D_fill_value_t *status);
 
diff --git a/src/H5Ppublic.h b/src/H5Ppublic.h
index 615967c..3ac1029 100644
--- a/src/H5Ppublic.h
+++ b/src/H5Ppublic.h
@@ -57,12 +57,14 @@ typedef herr_t (*H5P_cls_copy_func_t)(hid_t new_prop_id, hid_t old_prop_id,
 typedef herr_t (*H5P_cls_close_func_t)(hid_t prop_id, void *close_data);
 
 /* Define property list callback function pointer types */
-typedef herr_t (*H5P_prp_create_func_t)(const char *name, size_t size, void *def_value);
-typedef herr_t (*H5P_prp_set_func_t)(hid_t prop_id, const char *name, size_t size, void *value);
-typedef herr_t (*H5P_prp_get_func_t)(hid_t prop_id, const char *name, size_t size, void *value);
-typedef herr_t (*H5P_prp_delete_func_t)(hid_t prop_id, const char *name, size_t size, void *value);
-typedef herr_t (*H5P_prp_copy_func_t)(const char *name, size_t size, void *value);
-typedef herr_t (*H5P_prp_close_func_t)(const char *name, size_t size, void *value);
+typedef herr_t (*H5P_prp_cb1_t)(const char *name, size_t size, void *value);
+typedef herr_t (*H5P_prp_cb2_t)(hid_t prop_id, const char *name, size_t size, void *value);
+typedef H5P_prp_cb1_t H5P_prp_create_func_t;
+typedef H5P_prp_cb2_t H5P_prp_set_func_t;
+typedef H5P_prp_cb2_t H5P_prp_get_func_t;
+typedef H5P_prp_cb2_t H5P_prp_delete_func_t;
+typedef H5P_prp_cb1_t H5P_prp_copy_func_t;
+typedef H5P_prp_cb1_t H5P_prp_close_func_t;
 
 /* Define property list iteration function type */
 typedef herr_t (*H5P_iterate_t)(hid_t id, const char *name, void *iter_data); 
@@ -73,19 +75,25 @@ extern "C" {
 
 /*
  * The library created property list classes
+ *
+ * NOTE: When adding H5P_* macros, remember to redefine them in H5Pprivate.h
+ *
  */
-#define H5P_NO_CLASS		   	(H5open(), H5P_CLS_NO_CLASS_g)
-#define H5P_NO_CLASS_HASH_SIZE   1  /* 1, not 0, otherwise allocations get weird */
-#define H5P_FILE_CREATE 		(H5open(), H5P_CLS_FILE_CREATE_g)
-#define H5P_FILE_CREATE_HASH_SIZE  	17
-#define H5P_FILE_ACCESS 		(H5open(), H5P_CLS_FILE_ACCESS_g)
-#define H5P_FILE_ACCESS_HASH_SIZE   	17
-#define H5P_DATASET_CREATE     		(H5open(), H5P_CLS_DATASET_CREATE_g)
-#define H5P_DATASET_CREATE_HASH_SIZE   	17
-#define H5P_DATASET_XFER       		(H5open(), H5P_CLS_DATASET_XFER_g)
-#define H5P_DATASET_XFER_HASH_SIZE   	17
-#define H5P_MOUNT       		(H5open(), H5P_CLS_MOUNT_g)
-#define H5P_MOUNT_HASH_SIZE   		17
+
+/* When this header is included from H5Pprivate.h, don't make calls to H5open() */
+#undef H5OPEN
+#ifndef _H5Pprivate_H
+#define H5OPEN        H5open(),
+#else   /* _H5Pprivate_H */
+#define H5OPEN
+#endif  /* _H5Pprivate_H */
+
+#define H5P_NO_CLASS		   	(H5OPEN H5P_CLS_NO_CLASS_g)
+#define H5P_FILE_CREATE 		(H5OPEN H5P_CLS_FILE_CREATE_g)
+#define H5P_FILE_ACCESS 		(H5OPEN H5P_CLS_FILE_ACCESS_g)
+#define H5P_DATASET_CREATE     		(H5OPEN H5P_CLS_DATASET_CREATE_g)
+#define H5P_DATASET_XFER       		(H5OPEN H5P_CLS_DATASET_XFER_g)
+#define H5P_MOUNT       		(H5OPEN H5P_CLS_MOUNT_g)
 H5_DLLVAR hid_t H5P_CLS_NO_CLASS_g;
 H5_DLLVAR hid_t H5P_CLS_FILE_CREATE_g;
 H5_DLLVAR hid_t H5P_CLS_FILE_ACCESS_g;
@@ -95,13 +103,16 @@ H5_DLLVAR hid_t H5P_CLS_MOUNT_g;
 
 /*
  * The library created default property lists
+ *
+ * NOTE: When adding H5P_* macros, remember to redefine them in H5Pprivate.h
+ *
  */
-#define H5P_NO_CLASS_DEFAULT   		(H5open(), H5P_LST_NO_CLASS_g)
-#define H5P_FILE_CREATE_DEFAULT		(H5open(), H5P_LST_FILE_CREATE_g)
-#define H5P_FILE_ACCESS_DEFAULT 	(H5open(), H5P_LST_FILE_ACCESS_g)
-#define H5P_DATASET_CREATE_DEFAULT  	(H5open(), H5P_LST_DATASET_CREATE_g)
-#define H5P_DATASET_XFER_DEFAULT   	(H5open(), H5P_LST_DATASET_XFER_g)
-#define H5P_MOUNT_DEFAULT       	(H5open(), H5P_LST_MOUNT_g)
+#define H5P_NO_CLASS_DEFAULT   		(H5OPEN H5P_LST_NO_CLASS_g)
+#define H5P_FILE_CREATE_DEFAULT		(H5OPEN H5P_LST_FILE_CREATE_g)
+#define H5P_FILE_ACCESS_DEFAULT 	(H5OPEN H5P_LST_FILE_ACCESS_g)
+#define H5P_DATASET_CREATE_DEFAULT  	(H5OPEN H5P_LST_DATASET_CREATE_g)
+#define H5P_DATASET_XFER_DEFAULT   	(H5OPEN H5P_LST_DATASET_XFER_g)
+#define H5P_MOUNT_DEFAULT       	(H5OPEN H5P_LST_MOUNT_g)
 H5_DLLVAR hid_t H5P_LST_NO_CLASS_g;
 H5_DLLVAR hid_t H5P_LST_FILE_CREATE_g;
 H5_DLLVAR hid_t H5P_LST_FILE_ACCESS_g;
@@ -109,11 +120,8 @@ H5_DLLVAR hid_t H5P_LST_DATASET_CREATE_g;
 H5_DLLVAR hid_t H5P_LST_DATASET_XFER_g;
 H5_DLLVAR hid_t H5P_LST_MOUNT_g;
 
-/* Default hash table size */
-#define H5P_DEFAULT_HASH_SIZE           17
-
 /* Public functions */
-H5_DLL hid_t H5Pcreate_class(hid_t parent, const char *name, unsigned hashsize,
+H5_DLL hid_t H5Pcreate_class(hid_t parent, const char *name, 
             H5P_cls_create_func_t cls_create, void *create_data,
             H5P_cls_copy_func_t cls_copy, void *copy_data,
             H5P_cls_close_func_t cls_close, void *close_data);
diff --git a/src/H5R.c b/src/H5R.c
index 795bc56..1ffa827 100644
--- a/src/H5R.c
+++ b/src/H5R.c
@@ -331,7 +331,6 @@ done:
 static hid_t
 H5R_dereference(H5F_t *file, H5R_type_t ref_type, void *_ref)
 {
-    H5D_t *dataset;             /* Pointer to dataset to open */
     H5G_t *group;               /* Pointer to group to open */
     H5T_t *datatype;            /* Pointer to datatype to open */
     H5G_entry_t ent;            /* Symbol table entry */
@@ -428,14 +427,9 @@ H5R_dereference(H5F_t *file, H5R_type_t ref_type, void *_ref)
             break;
 
         case H5G_DATASET:
-            if ((dataset=H5D_open_oid(&ent)) == NULL)
+            /* Open the dataset */
+            if ((ret_value=H5D_open(&ent)) < 0)
                 HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, FAIL, "not found");
-
-            /* Create an atom for the dataset */
-            if ((ret_value = H5I_register(H5I_DATASET, dataset)) < 0) {
-                H5D_close(dataset);
-                HGOTO_ERROR(H5E_DATASET, H5E_CANTREGISTER, FAIL, "can't register dataset");
-            }
             break;
 
         default:
@@ -524,7 +518,6 @@ done:
 static H5S_t *
 H5R_get_region(H5F_t *file, H5R_type_t UNUSED ref_type, void *_ref)
 {
-    H5D_t *dataset;             /* Pointer to dataset to open */
     H5G_entry_t ent;            /* Symbol table entry */
     uint8_t *p;                 /* Pointer to OID to store */
     hdset_reg_ref_t *ref=(hdset_reg_ref_t *)_ref; /* Get pointer to correct type of reference struct */
@@ -556,12 +549,8 @@ H5R_get_region(H5F_t *file, H5R_type_t UNUSED ref_type, void *_ref)
     p=(uint8_t *)buf;
     H5F_addr_decode(ent.file,(const uint8_t **)&p,&(ent.header));
 
-    /* Open the dataset object */
-    if ((dataset=H5D_open_oid(&ent)) == NULL)
-        HGOTO_ERROR(H5E_DATASET, H5E_NOTFOUND, NULL, "not found");
-
-    /* Copy the dataspace object */
-    if ((ret_value=H5D_get_space(dataset)) == NULL)
+    /* Open and copy the dataset's dataspace */
+    if ((ret_value=H5S_read(&ent)) == NULL)
         HGOTO_ERROR(H5E_DATASPACE, H5E_NOTFOUND, NULL, "not found");
 
     /* Unserialize the selection */
@@ -571,10 +560,6 @@ H5R_get_region(H5F_t *file, H5R_type_t UNUSED ref_type, void *_ref)
     /* Free the buffer allocated in H5HG_read() */
     H5MM_xfree(buf);
 
-    /* Close the dataset we opened */
-    if (H5D_close(dataset) < 0)
-        HGOTO_ERROR(H5E_DATASET, H5E_CLOSEERROR, NULL, "not found");
-
 done:
     FUNC_LEAVE(ret_value);
 }   /* end H5R_get_region() */
diff --git a/src/H5RS.c b/src/H5RS.c
new file mode 100644
index 0000000..f6f18ac
--- /dev/null
+++ b/src/H5RS.c
@@ -0,0 +1,390 @@
+/****************************************************************************
+ * NCSA HDF								    *
+ * Software Development Group						    *
+ * National Center for Supercomputing Applications			    *
+ * University of Illinois at Urbana-Champaign				    *
+ * 605 E. Springfield, Champaign IL 61820				    *
+ *									    *
+ * For conditions of distribution and use, see the accompanying		    *
+ * hdf/COPYING file.							    *
+ *									    *
+ ****************************************************************************/
+
+/*
+ * Reference counted string algorithms.
+ *
+ * These are used for various internal strings which get copied multiple times.
+ *
+ */
+
+#include "H5Eprivate.h"		/* Error handling		  	*/
+#include "H5FLprivate.h"	/* Free lists                           */
+#include "H5RSprivate.h"        /* Reference-counted strings            */
+
+#define PABLO_MASK	H5RS_mask
+
+/* Interface initialization */
+static int		interface_initialize_g = 0;
+#define INTERFACE_INIT	NULL
+
+/* Declare a free list to manage the H5RS_str_t struct */
+H5FL_DEFINE_STATIC(H5RS_str_t);
+
+/* Declare the PQ free list for the wrapped strings */
+H5FL_BLK_DEFINE(str_buf);
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5RS_xstrdup
+ PURPOSE
+    Duplicate the string being reference counted
+ USAGE
+    char *H5RS_xstrdup(s)
+        const char *s;          IN: String to duplicate
+
+ RETURNS
+    Returns a pointer to a new string on success, NULL on failure.
+ DESCRIPTION
+    Duplicate a string buffer being reference counted.  Use this instead of
+    [H5MM_][x]strdup, in order to use the free-list memory routines.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+static char *
+H5RS_xstrdup(const char *s)
+{
+    char *ret_value;   /* Return value */
+
+    FUNC_ENTER_NOINIT(H5RS_xstrdup);
+
+    if (s) {
+        ret_value = H5FL_BLK_MALLOC(str_buf,HDstrlen(s) + 1);
+        assert (ret_value);
+        HDstrcpy(ret_value, s);
+    } /* end if */
+    else
+        ret_value=NULL;
+
+    FUNC_LEAVE(ret_value);
+} /* end H5RS_xstrdup() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5RS_create
+ PURPOSE
+    Create a reference counted string
+ USAGE
+    H5RS_str_t *H5RS_create(s)
+        const char *s;          IN: String to initialize ref-counted string with
+
+ RETURNS
+    Returns a pointer to a new ref-counted string on success, NULL on failure.
+ DESCRIPTION
+    Create a reference counted string.  The string passed in is copied into an
+    internal buffer.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+H5RS_str_t *
+H5RS_create(const char *s)
+{
+    H5RS_str_t *ret_value=NULL;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5RS_create,NULL);
+
+    /* Allocate ref-counted string structure */
+    if((ret_value=H5FL_MALLOC(H5RS_str_t))==NULL)
+        HGOTO_ERROR(H5E_RS,H5E_NOSPACE,NULL,"memory allocation failed");
+
+    /* Set the internal fields */
+    ret_value->s=H5RS_xstrdup(s);
+    ret_value->wrapped=0;
+    ret_value->n=1;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5RS_create() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5RS_wrap
+ PURPOSE
+    "Wrap" a reference counted string around an existing string
+ USAGE
+    H5RS_str_t *H5RS_wrap(s)
+        const char *s;          IN: String to wrap ref-counted string around
+
+ RETURNS
+    Returns a pointer to a new ref-counted string on success, NULL on failure.
+ DESCRIPTION
+    Wrap a reference counted string around an existing string, which is not
+    duplicated, unless its reference count gets incremented.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+H5RS_str_t *
+H5RS_wrap(char *s)
+{
+    H5RS_str_t *ret_value=NULL;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5RS_wrap,NULL);
+
+    /* Allocate ref-counted string structure */
+    if((ret_value=H5FL_MALLOC(H5RS_str_t))==NULL)
+        HGOTO_ERROR(H5E_RS,H5E_NOSPACE,NULL,"memory allocation failed");
+
+    /* Set the internal fields */
+    ret_value->s=s;
+    ret_value->wrapped=1;
+    ret_value->n=1;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5RS_wrap() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5RS_own
+ PURPOSE
+    Transfer ownership of a regular string to  a reference counted string
+ USAGE
+    H5RS_str_t *H5RS_own(s)
+        const char *s;          IN: String to transfer ownership of
+
+ RETURNS
+    Returns a pointer to a new ref-counted string on success, NULL on failure.
+ DESCRIPTION
+    Transfer ownership of a dynamically allocated string to a reference counted
+    string.  The routine which passed in the string should not attempt to free
+    it, the reference counting string routines will do that when the reference
+    count drops to zero.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+H5RS_str_t *
+H5RS_own(char *s)
+{
+    H5RS_str_t *ret_value=NULL;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5RS_own,NULL);
+
+    /* Allocate ref-counted string structure */
+    if((ret_value=H5FL_MALLOC(H5RS_str_t))==NULL)
+        HGOTO_ERROR(H5E_RS,H5E_NOSPACE,NULL,"memory allocation failed");
+
+    /* Set the internal fields */
+    ret_value->s=s;
+    ret_value->wrapped=0;
+    ret_value->n=1;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5RS_own() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5RS_decr
+ PURPOSE
+    Decrement the reference count for a ref-counted string
+ USAGE
+    herr_t H5RS_decr(rs)
+        H5RS_str_t *rs;     IN/OUT: Ref-counted string to decrement count of
+
+ RETURNS
+    Non-negative on success/Negative on failure
+ DESCRIPTION
+    Decrement the reference count for a reference counted string.  If the
+    reference count drops to zero, the reference counted string is deleted.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5RS_decr(H5RS_str_t *rs)
+{
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5RS_decr,FAIL);
+
+    /* Sanity check */
+    assert(rs);
+    assert(rs->n > 0);
+
+    /* Decrement reference count for string */
+    if((--rs->n)==0) {
+        if(!rs->wrapped)
+            H5FL_BLK_FREE(str_buf,rs->s);
+        H5FL_FREE(H5RS_str_t,rs);
+    } /* end if */
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5RS_decr() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5RS_incr
+ PURPOSE
+    Increment the reference count for a ref-counted string
+ USAGE
+    herr_t H5RS_incr(rs)
+        H5RS_str_t *rs;     IN/OUT: Ref-counted string to increment count of
+
+ RETURNS
+    Non-negative on success/Negative on failure
+ DESCRIPTION
+    Increment the reference count for a reference counted string.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5RS_incr(H5RS_str_t *rs)
+{
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5RS_incr,FAIL);
+
+    /* Sanity check */
+    assert(rs);
+    assert(rs->n > 0);
+
+    /* If the ref-counted string started life as a wrapper around an existing
+     * string, duplicate the string now, so that the wrapped string can go out
+     * scope appropriately.
+     */
+    if(rs->wrapped) {
+        rs->s=H5RS_xstrdup(rs->s);
+        rs->wrapped=0;
+    } /* end if */
+
+    /* Increment reference count for string */
+    rs->n++;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5RS_incr() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5RS_dup
+ PURPOSE
+    "Duplicate" a ref-counted string
+ USAGE
+    H5RS_str_t H5RS_incr(rs)
+        H5RS_str_t *rs;     IN/OUT: Ref-counted string to "duplicate"
+
+ RETURNS
+    Returns a pointer to ref-counted string on success, NULL on failure.
+ DESCRIPTION
+    Increment the reference count for the reference counted string and return
+    a pointer to it.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+H5RS_str_t *
+H5RS_dup(H5RS_str_t *ret_value)
+{
+    FUNC_ENTER_NOAPI(H5RS_dup,NULL);
+
+    /* Check for valid reference counted string */
+    if(ret_value!=NULL)
+        /* Increment reference count for string */
+        ret_value->n++;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5RS_dup() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5RS_cmp
+ PURPOSE
+    Compare two ref-counted strings
+ USAGE
+    int H5RS_cmp(rs1,rs2)
+        const H5RS_str_t *rs1;  IN: First Ref-counted string to compare
+        const H5RS_str_t *rs2;  IN: Second Ref-counted string to compare
+
+ RETURNS
+    Returns positive, negative or 0 for comparison of two r-strings [same as
+    strcmp()]
+ DESCRIPTION
+    Compare two ref-counted strings and return a value indicating their sort
+    order [same as strcmp()]
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+int
+H5RS_cmp(const H5RS_str_t *rs1, const H5RS_str_t *rs2)
+{
+    /* Can't return invalid value from this function */
+    FUNC_ENTER_NOINIT(H5RS_cmp);
+
+    /* Sanity check */
+    assert(rs1);
+    assert(rs1->s);
+    assert(rs2);
+    assert(rs2->s);
+
+    FUNC_LEAVE(HDstrcmp(rs1->s,rs2->s));
+} /* end H5RS_cmp() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5RS_len
+ PURPOSE
+    Compute the length of a ref-counted string
+ USAGE
+    ssize_t H5RS_cmp(rs)
+        const H5RS_str_t *rs;  IN: Ref-counted string to compute length of
+
+ RETURNS
+    Returns non-negative value on success, negative value on failure
+ DESCRIPTION
+    Compute the length of a ref-counted string.  [same as strlen()]
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+ssize_t
+H5RS_len(const H5RS_str_t *rs)
+{
+    ssize_t ret_value;     /* Return value */
+
+    FUNC_ENTER_NOAPI(H5RS_len,FAIL);
+
+    /* Sanity check */
+    assert(rs);
+    assert(rs->s);
+
+    ret_value=HDstrlen(rs->s);
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5RS_len() */
+
diff --git a/src/H5RSprivate.h b/src/H5RSprivate.h
new file mode 100644
index 0000000..086396f
--- /dev/null
+++ b/src/H5RSprivate.h
@@ -0,0 +1,52 @@
+/****************************************************************************
+ * NCSA HDF								    *
+ * Software Development Group						    *
+ * National Center for Supercomputing Applications			    *
+ * University of Illinois at Urbana-Champaign				    *
+ * 605 E. Springfield, Champaign IL 61820				    *
+ *									    *
+ * For conditions of distribution and use, see the accompanying		    *
+ * hdf/COPYING file.							    *
+ *									    *
+ ****************************************************************************/
+
+/*
+ * This file contains private information about the H5RS module
+ */
+#ifndef _H5RSprivate_H
+#define _H5RSprivate_H
+
+#ifdef LATER
+#include "H5RSpublic.h"
+#endif /* LATER */
+
+/* Private headers needed by this file */
+#include "H5private.h"
+
+/* Typedefs */
+
+/* Typedef for reference counted string */
+typedef struct {
+    char *s;            /* String to be reference counted */
+    unsigned wrapped;   /* Indicates that the string to be ref-counted is not copied */
+    unsigned n;         /* Reference count of number of pointers sharing string */
+} H5RS_str_t;
+
+/* Macros */
+
+/* Get the pointer to the actual string */
+#define H5RS_GET_STR(rs)        ((rs)->s)
+#define H5RS_GET_COUNT(rs)      ((rs)->n)
+
+/* Private routines */
+H5_DLL H5RS_str_t *H5RS_create(const char *s);
+H5_DLL H5RS_str_t *H5RS_wrap(char *s);
+H5_DLL H5RS_str_t *H5RS_own(char *s);
+H5_DLL herr_t H5RS_decr(H5RS_str_t *rs);
+H5_DLL herr_t H5RS_incr(H5RS_str_t *rs);
+H5_DLL H5RS_str_t *H5RS_dup(H5RS_str_t *s);
+H5_DLL int H5RS_cmp(const H5RS_str_t *rs1, const H5RS_str_t *rs2);
+H5_DLL ssize_t H5RS_len(const H5RS_str_t *rs);
+
+#endif /* _H5STprivate_H */
+
diff --git a/src/H5S.c b/src/H5S.c
index 6424ada..0127056 100644
--- a/src/H5S.c
+++ b/src/H5S.c
@@ -303,8 +303,21 @@ H5S_create(H5S_class_t type)
     FUNC_ENTER_NOAPI(H5S_create, NULL);
 
     /* Create a new data space */
-    if((ret_value = H5FL_ALLOC(H5S_t,1))!=NULL) {
+    if((ret_value = H5FL_CALLOC(H5S_t))!=NULL) {
         ret_value->extent.type = type;
+
+        switch(type) {
+            case H5S_SCALAR:
+                ret_value->extent.nelem = 1;
+                break;
+            case H5S_SIMPLE:
+                ret_value->extent.nelem = 0;
+                break;
+            default:
+                assert("unknown dataspace (extent) type" && 0);
+                break;
+        } /* end switch */
+
         if(H5S_select_all(ret_value,0)<0)
             HGOTO_ERROR (H5E_DATASPACE, H5E_CANTSET, NULL, "unable to set all selection");
     } /* end if */
@@ -647,12 +660,12 @@ H5S_extent_copy(H5S_extent_t *dst, const H5S_extent_t *src)
 
         case H5S_SIMPLE:
             if (src->u.simple.size) {
-                dst->u.simple.size = H5FL_ARR_ALLOC(hsize_t,src->u.simple.rank,0);
+                dst->u.simple.size = H5FL_ARR_MALLOC(hsize_t,src->u.simple.rank);
                 for (u = 0; u < src->u.simple.rank; u++)
                     dst->u.simple.size[u] = src->u.simple.size[u];
             }
             if (src->u.simple.max) {
-                dst->u.simple.max = H5FL_ARR_ALLOC(hsize_t,src->u.simple.rank,0);
+                dst->u.simple.max = H5FL_ARR_MALLOC(hsize_t,src->u.simple.rank);
                 for (u = 0; u < src->u.simple.rank; u++)
                     dst->u.simple.max[u] = src->u.simple.max[u];
             }
@@ -697,7 +710,7 @@ H5S_copy(const H5S_t *src)
 
     FUNC_ENTER_NOAPI(H5S_copy, NULL);
 
-    if (NULL==(dst = H5FL_ALLOC(H5S_t,0)))
+    if (NULL==(dst = H5FL_MALLOC(H5S_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* Copy the field in the struct */
@@ -740,30 +753,14 @@ hssize_t
 H5S_get_simple_extent_npoints(const H5S_t *ds)
 {
     hssize_t    ret_value;
-    unsigned		u;
 
     FUNC_ENTER_NOAPI(H5S_get_simple_extent_npoints, -1);
 
     /* check args */
     assert(ds);
 
-    switch (ds->extent.type) {
-        case H5S_SCALAR:
-            ret_value = 1;
-            break;
-
-        case H5S_SIMPLE:
-            for (ret_value=1, u=0; u<ds->extent.u.simple.rank; u++)
-                ret_value *= ds->extent.u.simple.size[u];
-            break;
-
-        case H5S_COMPLEX:
-            HGOTO_ERROR(H5E_DATASPACE, H5E_UNSUPPORTED, FAIL, "complex data spaces are not supported yet");
-
-        default:
-            assert("unknown data space class" && 0);
-            HGOTO_ERROR(H5E_DATASPACE, H5E_UNSUPPORTED, FAIL, "internal error (unknown data space class)");
-    }
+    /* Get the number of elements in extent */
+    ret_value = ds->extent.nelem;
 
 done:
     FUNC_LEAVE(ret_value);
@@ -1078,7 +1075,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5S_modify(H5G_entry_t *ent, const H5S_t *ds)
+H5S_modify(H5G_entry_t *ent, const H5S_t *ds, hbool_t update_time)
 {
     herr_t ret_value=SUCCEED;   /* Return value */
 
@@ -1090,7 +1087,7 @@ H5S_modify(H5G_entry_t *ent, const H5S_t *ds)
     switch (ds->extent.type) {
         case H5S_SCALAR:
         case H5S_SIMPLE:
-            if (H5O_modify(ent, H5O_SDSPACE, 0, 0, &(ds->extent.u.simple))<0)
+            if (H5O_modify(ent, H5O_SDSPACE, 0, 0, update_time, &(ds->extent.u.simple))<0)
                 HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "can't update simple data space message");
             break;
 
@@ -1108,6 +1105,52 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5S_append
+ *
+ * Purpose:	Updates a data space by adding a message to an object
+ *		header.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *		Tuesday, December 31, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5S_append(H5F_t *f, H5O_t *oh, const H5S_t *ds)
+{
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5S_append, FAIL);
+
+    assert(f);
+    assert(oh);
+    assert(ds);
+
+    switch (ds->extent.type) {
+        case H5S_SCALAR:
+        case H5S_SIMPLE:
+            if (H5O_append(f, oh, H5O_SDSPACE, 0, &(ds->extent.u.simple))<0)
+                HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, FAIL, "can't update simple data space message");
+            break;
+
+        case H5S_COMPLEX:
+            HGOTO_ERROR(H5E_DATASPACE, H5E_UNSUPPORTED, FAIL, "complex data spaces are not implemented yet");
+
+        default:
+            assert("unknown data space class" && 0);
+            break;
+    }
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5S_append() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5S_read
  *
  * Purpose:	Reads the data space from an object header.
@@ -1136,23 +1179,34 @@ H5S_read(H5G_entry_t *ent)
     /* check args */
     assert(ent);
 
-    if (NULL==(ds = H5FL_ALLOC(H5S_t,1)))
+    if (NULL==(ds = H5FL_CALLOC(H5S_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     if (H5O_read(ent, H5O_SDSPACE, 0, &(ds->extent.u.simple)) == NULL)
         HGOTO_ERROR(H5E_DATASPACE, H5E_CANTINIT, NULL, "unable to load dataspace info from dataset header");
 
-    if(ds->extent.u.simple.rank != 0)
-         ds->extent.type = H5S_SIMPLE;
-    else
-         ds->extent.type = H5S_SCALAR;
+    if(ds->extent.u.simple.rank != 0) {
+        hsize_t nelem;  /* Number of elements in extent */
+        unsigned u;     /* Local index variable */
+
+        ds->extent.type = H5S_SIMPLE;
+
+        /* Compute the number of elements in the extent */
+        for(u=0, nelem=1; u<ds->extent.u.simple.rank; u++)
+            nelem*=ds->extent.u.simple.size[u];
+        ds->extent.nelem = nelem;
+    } /* end if */
+    else {
+        ds->extent.type = H5S_SCALAR;
+        ds->extent.nelem = 1;
+    } /* end else */
 
     /* Default to entire dataspace being selected */
     if(H5S_select_all(ds,0)<0)
         HGOTO_ERROR (H5E_DATASPACE, H5E_CANTSET, NULL, "unable to set all selection");
 
     /* Allocate space for the offset and set it to zeros */
-    if (NULL==(ds->select.offset = H5FL_ARR_ALLOC(hssize_t,ds->extent.u.simple.rank,1)))
+    if (NULL==(ds->select.offset = H5FL_ARR_CALLOC(hssize_t,ds->extent.u.simple.rank)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* Set the value for successful return */
@@ -1407,7 +1461,7 @@ H5S_set_extent_simple (H5S_t *space, unsigned rank, const hsize_t *dims,
         space->select.offset=H5FL_ARR_FREE(hssize_t,space->select.offset);
 
     /* Allocate space for the offset and set it to zeros */
-    if (NULL==(space->select.offset = H5FL_ARR_ALLOC(hssize_t,rank,1)))
+    if (NULL==(space->select.offset = H5FL_ARR_CALLOC(hssize_t,rank)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
     /* shift out of the previous state to a "simple" dataspace */
@@ -1433,18 +1487,27 @@ H5S_set_extent_simple (H5S_t *space, unsigned rank, const hsize_t *dims,
 
     if (rank == 0) {		/* scalar variable */
         space->extent.type = H5S_SCALAR;
+        space->extent.nelem = 1;
         space->extent.u.simple.rank = 0;	/* set to scalar rank */
     } else {
+        hsize_t nelem;  /* Number of elements in extent */
+        unsigned u;     /* Local index variable */
+
         space->extent.type = H5S_SIMPLE;
 
         /* Set the rank and copy the dims */
         space->extent.u.simple.rank = rank;
-        space->extent.u.simple.size = H5FL_ARR_ALLOC(hsize_t,rank,0);
+        space->extent.u.simple.size = H5FL_ARR_MALLOC(hsize_t,rank);
         HDmemcpy(space->extent.u.simple.size, dims, sizeof(hsize_t) * rank);
 
+        /* Compute the number of elements in the extent */
+        for(u=0, nelem=1; u<space->extent.u.simple.rank; u++)
+            nelem*=space->extent.u.simple.size[u];
+        space->extent.nelem = nelem;
+
         /* Copy the maximum dimensions if specified */
         if(max!=NULL) {
-            space->extent.u.simple.max = H5FL_ARR_ALLOC(hsize_t,rank,0);
+            space->extent.u.simple.max = H5FL_ARR_MALLOC(hsize_t,rank);
             HDmemcpy(space->extent.u.simple.max, max, sizeof(hsize_t) * rank);
         } /* end if */
     }
@@ -1629,6 +1692,7 @@ H5S_extend (H5S_t *space, const hsize_t *size)
     assert (space && H5S_SIMPLE==space->extent.type);
     assert (size);
 
+    /* Check through all the dimensions to see if modifying the dataspace is allowed */
     for (u=0; u<space->extent.u.simple.rank; u++) {
         if (space->extent.u.simple.size[u]<size[u]) {
             if (space->extent.u.simple.max &&
@@ -1641,10 +1705,16 @@ H5S_extend (H5S_t *space, const hsize_t *size)
 
     /* Update */
     if (ret_value) {
-        for (u=0; u<space->extent.u.simple.rank; u++) {
+        hsize_t nelem;  /* Number of elements in extent */
+
+        /* Change the dataspace size & re-compute the number of elements in the extent */
+        for (u=0, nelem=1; u<space->extent.u.simple.rank; u++) {
             if (space->extent.u.simple.size[u]<size[u])
                 space->extent.u.simple.size[u] = size[u];
+
+            nelem*=space->extent.u.simple.size[u];
         }
+        space->extent.nelem = nelem;
     }
 
 done:
@@ -1872,7 +1942,7 @@ H5Soffset_simple(hid_t space_id, const hssize_t *offset)
 
     /* Allocate space for new offset */
     if(space->select.offset==NULL) {
-        if (NULL==(space->select.offset = H5FL_ARR_ALLOC(hssize_t,space->extent.u.simple.rank,0)))
+        if (NULL==(space->select.offset = H5FL_ARR_MALLOC(hssize_t,space->extent.u.simple.rank)))
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     }
 
@@ -1922,9 +1992,14 @@ H5S_set_extent( H5S_t *space, const hsize_t *size )
 
     /* Update */
     if (ret_value) {
-        /* Update dimensions with new values */
-        for ( u = 0; u < space->extent.u.simple.rank; u++ )
+        hsize_t nelem;  /* Number of elements in extent */
+
+        /* Change the dataspace size & re-compute the number of elements in the extent */
+        for (u=0, nelem=1; u < space->extent.u.simple.rank; u++ ) {
             space->extent.u.simple.size[u] = size[u];
+            nelem*=space->extent.u.simple.size[u];
+        } /* end for */
+        space->extent.nelem = nelem;
     } /* end if */
 
 done:
diff --git a/src/H5ST.c b/src/H5ST.c
new file mode 100644
index 0000000..35b6ab8
--- /dev/null
+++ b/src/H5ST.c
@@ -0,0 +1,795 @@
+/****************************************************************************
+ * NCSA HDF								    *
+ * Software Development Group						    *
+ * National Center for Supercomputing Applications			    *
+ * University of Illinois at Urbana-Champaign				    *
+ * 605 E. Springfield, Champaign IL 61820				    *
+ *									    *
+ * For conditions of distribution and use, see the accompanying		    *
+ * hdf/COPYING file.							    *
+ *									    *
+ ****************************************************************************/
+
+/* TERNARY SEARCH TREE ALGS
+  This code is described in "Ternary Search Trees" by Jon
+Bentley and Robert Sedgewick in the April, 1998, Dr. Dobb's Journal.
+*/
+
+#include "H5Eprivate.h"		/* Error handling		  	*/
+#include "H5FLprivate.h"	/* Free lists                           */
+#include "H5STprivate.h"        /* Ternary search trees                 */
+
+#define PABLO_MASK	H5ST_mask
+static int		interface_initialize_g = 0;
+#define INTERFACE_INIT	NULL
+
+/* Declare a free list to manage the H5ST_node_t struct */
+H5FL_DEFINE_STATIC(H5ST_node_t);
+
+/* Declare a free list to manage the H5ST_tree_t struct */
+H5FL_DEFINE_STATIC(H5ST_tree_t);
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_create
+ PURPOSE
+    Create a TST
+ USAGE
+    H5ST_ptr_t H5ST_create()
+
+ RETURNS
+    Returns a pointer to the new TST tree on success, NULL on failure.
+ DESCRIPTION
+    Create a TST.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+H5ST_tree_t *
+H5ST_create(void)
+{
+    H5ST_tree_t *ret_value=NULL;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_create,NULL);
+
+    /* Allocate wrapper for TST */
+    if((ret_value=H5FL_MALLOC(H5ST_tree_t))==NULL)
+        HGOTO_ERROR(H5E_RESOURCE,H5E_NOSPACE,NULL,"memory allocation failed");
+
+    /* Set the internal fields */
+    ret_value->root=NULL;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_create() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_close_internal
+ PURPOSE
+    Close a TST, deallocating it.
+ USAGE
+    herr_t H5ST_close(p)
+        H5ST_ptr_t p;        IN/OUT: Root of TST to free
+
+ RETURNS
+    Returns non-negative on success, negative on failure.
+ DESCRIPTION
+    Close a TST, freeing all nodes.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+static herr_t
+H5ST_close_internal(H5ST_ptr_t p)
+{
+    FUNC_ENTER_NOINIT(H5ST_close_internal);
+
+    /* Recursively free TST */
+    if(p) {
+        H5ST_close_internal(p->lokid);
+        if (p->splitchar)
+            H5ST_close_internal(p->eqkid);
+        H5ST_close_internal(p->hikid);
+        H5FL_FREE(H5ST_node_t,p);
+    } /* end if */
+
+    FUNC_LEAVE(SUCCEED);
+} /* end H5ST_close_internal() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_close
+ PURPOSE
+    Close a TST, deallocating it.
+ USAGE
+    herr_t H5ST_close(tree)
+        H5ST_tree_t *tree;        IN/OUT: TST tree to free
+
+ RETURNS
+    Returns non-negative on success, negative on failure.
+ DESCRIPTION
+    Close a TST, freeing all nodes.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5ST_close(H5ST_tree_t *tree)
+{
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_close,FAIL);
+
+    /* Check arguments */
+    if(tree==NULL)
+        HGOTO_ERROR(H5E_ARGS,H5E_BADVALUE,FAIL,"invalid TST");
+
+    /* Free the TST itself */
+    if(H5ST_close_internal(tree->root)<0)
+        HGOTO_ERROR(H5E_TST,H5E_CANTFREE,FAIL,"can't free TST");
+
+    /* Free root node itself */
+    H5FL_FREE(H5ST_tree_t,tree);
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_close() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_insert
+ PURPOSE
+    Insert a string/object pair into a TST
+ USAGE
+    herr_t H5ST_insert(tree,s,obj)
+        H5ST_tree_t *tree;      IN/OUT: TST to insert string into
+        const char *s;          IN: String to use as key for object
+        void *obj;              IN: Pointer to object to insert
+
+ RETURNS
+    Returns non-negative on success, negative on failure.
+ DESCRIPTION
+    Insert a key (string)/object pair into a TST
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5ST_insert(H5ST_tree_t *tree, const char *s, void *obj)
+{
+    int d;                      /* Comparison value */
+    H5ST_ptr_t pp, *p;          /* Pointer to current node and pointer to that */
+    H5ST_ptr_t parent=NULL;     /* Pointer to parent node */
+    H5ST_ptr_t up=NULL;         /* Pointer to up node */
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_insert,FAIL);
+
+    /* Find the correct location to insert object */
+    p = &tree->root;
+    while((pp = *p)) {
+        /* If this node matches the character in the key, then drop down to the lower tree */
+        if ((d = *s - pp->splitchar) == 0) {
+            if (*s++ == 0)
+                HGOTO_ERROR(H5E_TST,H5E_EXISTS,FAIL,"key already in tree");
+            up=pp;
+            p = &(pp->eqkid);
+        } /* end if */
+        else {
+            /* Walk through the current tree, searching for the matching character */
+            parent=pp;
+            if (d < 0)
+                p = &(pp->lokid);
+            else
+                p = &(pp->hikid);
+        } /* end else */
+    } /* end while */
+
+    /* Finish walking through the key string, adding nodes until the end */
+    for (;;) {
+        if((*p = H5FL_MALLOC(H5ST_node_t))==NULL)
+            HGOTO_ERROR(H5E_RESOURCE,H5E_NOSPACE,FAIL,"memory allocation failed");
+        pp = *p;
+        pp->splitchar = *s;
+        pp->up = up;
+        pp->parent = parent;
+        pp->lokid = pp->eqkid = pp->hikid = NULL;
+
+        /* If this is the end of the key string, break out */
+        if (*s++ == 0) {
+            pp->eqkid = (H5ST_ptr_t) obj;
+            break;
+        } /* end if */
+
+        /* Continue to next character */
+        parent=NULL;
+        up=pp;
+        p = &(pp->eqkid);
+    } /* end for */
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_insert() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_search
+ PURPOSE
+    Determine if a key is in the TST
+ USAGE
+    hbool_t H5ST_search(tree,s)
+        H5ST_tree_t *tree;      IN: TST to find string in
+        const char *s;          IN: String to use as key to locate
+
+ RETURNS
+    Success: TRUE if key string in TST, FALSE if not
+    Failure: negative
+ DESCRIPTION
+    Locate a key (string) in a TST
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+htri_t
+H5ST_search(H5ST_tree_t *tree, const char *s)
+{
+    H5ST_ptr_t p;               /* Temporary pointer to TST node */
+    htri_t ret_value=FALSE;     /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_search,FAIL);
+
+    p = tree->root;
+    while (p) {
+        if (*s < p->splitchar)
+            p = p->lokid;
+        else if (*s == p->splitchar)  {
+            if (*s++ == 0)
+                HGOTO_DONE(TRUE);
+            p = p->eqkid;
+        } else
+            p = p->hikid;
+    } /* end while */
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_search() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_find_internal
+ PURPOSE
+    Find the node matching a particular key string
+ USAGE
+    H5ST_ptr_t H5ST_find(p,s)
+        H5ST_ptr_t p;           IN: TST to find string in
+        const char *s;          IN: String to use as key to locate
+
+ RETURNS
+    Success: Non-NULL
+    Failure: NULL
+ DESCRIPTION
+    Locate a key (string) in a TST
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+static H5ST_ptr_t
+H5ST_find_internal(H5ST_ptr_t p, const char *s)
+{
+    H5ST_ptr_t ret_value=NULL;  /* Return value */
+
+    FUNC_ENTER_NOINIT(H5ST_find_internal);
+
+    while (p) {
+        if (*s < p->splitchar)
+            p = p->lokid;
+        else if (*s == p->splitchar)  {
+            if (*s++ == 0)
+                HGOTO_DONE(p);
+            p = p->eqkid;
+        } else
+            p = p->hikid;
+    } /* end while */
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_find_internal() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_find
+ PURPOSE
+    Find the node matching a particular key string
+ USAGE
+    H5ST_ptr_t H5ST_find(tree,s)
+        H5ST_tree_t *tree;      IN: TST to find string in
+        const char *s;          IN: String to use as key to locate
+
+ RETURNS
+    Success: Non-NULL
+    Failure: NULL
+ DESCRIPTION
+    Locate a key (string) in a TST
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+H5ST_ptr_t
+H5ST_find(H5ST_tree_t *tree, const char *s)
+{
+    H5ST_ptr_t ret_value=NULL;  /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_find,NULL);
+
+    if((ret_value=H5ST_find_internal(tree->root,s))==NULL)
+        HGOTO_ERROR(H5E_TST,H5E_NOTFOUND,NULL,"key not found in TST");
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_find() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_locate
+ PURPOSE
+    Find an object in a TST
+ USAGE
+    void *H5ST_locate(tree,s)
+        H5ST_tree_t *tree;  IN: TST to locate object within
+        const char *s;      IN: String of key for object to locate
+ RETURNS
+    Success: Non-NULL, pointer to object stored for key
+    Failure: Negative
+ DESCRIPTION
+    Locate a node in a TST, returning the object from the node.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+void *
+H5ST_locate(H5ST_tree_t *tree, const char *s)
+{
+    H5ST_ptr_t node;    /* Pointer to node located */
+    void *ret_value;    /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_locate,NULL);
+
+    /* Locate the node to remove */
+    if((node=H5ST_find_internal(tree->root,s))==NULL)
+        HGOTO_ERROR(H5E_TST,H5E_NOTFOUND,NULL,"key not found in TST");
+
+    /* Get the pointer to the object to return */
+    ret_value=node->eqkid;
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* H5ST_locate() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_findfirst_internal
+ PURPOSE
+    Find the first node in a TST
+ USAGE
+    H5ST_ptr_t H5ST_findfirst_internal(p)
+        H5ST_ptr_t p;      IN: TST to locate first node within
+ RETURNS
+    Success: Non-NULL
+    Failure: NULL
+ DESCRIPTION
+    Get the first (lexicographically) node in a TST
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+static H5ST_ptr_t
+H5ST_findfirst_internal(H5ST_ptr_t p)
+{   
+    H5ST_ptr_t ret_value=NULL;  /* Return value */
+
+    FUNC_ENTER_NOINIT(H5ST_findfirst_internal);
+
+    while(p) {
+        /* Find least node in current tree */
+        while(p->lokid)
+            p=p->lokid;
+
+        /* Is least node '\0'? */
+        if(p->splitchar=='\0') {
+            /* Return it */
+            HGOTO_DONE(p);
+        } /* end if */
+        else {
+            /* Go down to next level of tree */
+            p=p->eqkid;
+        } /* end else */
+    } /* end while */
+            
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_findfirst_internal() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_findfirst
+ PURPOSE
+    Find the first node in a TST
+ USAGE
+    H5ST_ptr_t H5ST_findfirst(tree)
+        H5ST_tree_t *tree;      IN: TST to locate first node within
+ RETURNS
+    Success: Non-NULL
+    Failure: NULL
+ DESCRIPTION
+    Get the first (lexicographically) node in a TST
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+H5ST_ptr_t
+H5ST_findfirst(H5ST_tree_t *tree)
+{   
+    H5ST_ptr_t ret_value;       /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_findfirst,NULL);
+
+    if((ret_value=H5ST_findfirst_internal(tree->root))==NULL)
+        HGOTO_ERROR(H5E_TST,H5E_NOTFOUND,NULL,"no nodes in TST");
+            
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_findfirst() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_getnext
+ PURPOSE
+    Internal routine to find the next node in a given level of a TST
+ USAGE
+    H5ST_ptr_t H5ST_getnext(p)
+        H5ST_ptr_t *p;       IN: Pointer to node to find next node from
+ RETURNS
+    Success: Non-NULL
+    Failure: NULL
+ DESCRIPTION
+    Get the next (lexicographically) node in the current level of a TST
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+static H5ST_ptr_t
+H5ST_getnext(H5ST_ptr_t p)
+{
+    H5ST_ptr_t ret_value=NULL;  /* Return value */
+
+    FUNC_ENTER_NOINIT(H5ST_getnext);
+
+    /* If the node to continue from has higher-valued nodes attached */
+    if(p->hikid) {
+        /* Go to first higher-valued node */
+        p=p->hikid;
+
+        /* Find least node from here */
+        while(p->lokid)
+            p=p->lokid;
+        HGOTO_DONE(p);
+    } /* end if */
+    else {
+        H5ST_ptr_t q;           /* Temporary TST node pointer */
+
+        /* Go up one level in current tree */
+        q=p->parent;
+        if(q==NULL)
+            HGOTO_DONE(NULL);
+
+        /* While the previous node was the higher-valued node, keep backing up the tree */
+        while(q->hikid==p) {
+            p=q;
+            q=p->parent;
+            if(q==NULL)
+                HGOTO_DONE(NULL);
+        } /* end while */
+        HGOTO_DONE(q);
+    } /* end else */
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_getnext() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_findnext
+ PURPOSE
+    Find the next node from a node in a TST
+ USAGE
+    H5ST_ptr_t H5ST_findnext(p)
+        H5ST_ptr_t p;       IN: Current node to continue from
+ RETURNS
+    Success: Non-NULL
+    Failure: NULL
+ DESCRIPTION
+    Get the next (lexicographically) node in a TST
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+H5ST_ptr_t
+H5ST_findnext(H5ST_ptr_t p)
+{   
+    H5ST_ptr_t q;               /* Temporary pointer to TST node */
+    H5ST_ptr_t ret_value=NULL;  /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_findnext,NULL);
+
+    /* Find the next node at the current level, or go back up the tree */
+    do {
+        q=H5ST_getnext(p);
+        if(q) {
+            HGOTO_DONE(H5ST_findfirst_internal(q->eqkid));
+        } /* end if */
+        else
+            p=p->up;
+    } while(p);
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_findnext() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_delete_internal
+ PURPOSE
+    Delete a node from a TST
+ USAGE
+    herr_t H5ST_delete_internal(root,p)
+        H5ST_ptr_t *root;       IN/OUT: Root of TST to delete node from
+        H5ST_ptr_t p;       IN: Node to delete
+ RETURNS
+    Success: Non-negative
+    Failure: Negative
+ DESCRIPTION
+    Delete a node from a TST.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+    This should be the final node for a string.
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+static herr_t
+H5ST_delete_internal(H5ST_ptr_t *root, H5ST_ptr_t p)
+{   
+    H5ST_ptr_t q,               /* Temporary pointer to TST node */
+        newp;                   /* Pointer to node which will replace deleted node in tree */
+
+    FUNC_ENTER_NOINIT(H5ST_delete_internal);
+
+    /* Find node to replace one being deleted */
+    if(p->lokid) {
+        /* If the deleted node has lo & hi kids, attach them together */
+        if(p->hikid) {
+            q=p->lokid;
+            while(q->hikid)
+                q=q->hikid;
+            q->hikid=p->hikid;
+            p->hikid->parent=q;
+        } /* end if */
+        newp=p->lokid;
+    } /* end if */
+    else if(p->hikid) {
+        newp=p->hikid;
+    } /* end if */
+    else {
+        newp=NULL;
+    } /* end else */
+
+    /* Deleted node is in middle of tree */
+    if(p->parent) {
+        /* Attach new node to correct side of parent */
+        if(p==p->parent->lokid)
+            p->parent->lokid=newp;
+        else
+            p->parent->hikid=newp;
+        if(newp)
+            newp->parent=p->parent;
+    } /* end if */
+    else {
+        if(newp)
+            newp->parent=p->parent;
+        if(p->up) {
+            p->up->eqkid=newp;
+            /* If we deleted the last node in the TST, delete the upper node also */
+            if(newp==NULL)
+                H5ST_delete_internal(root,p->up);
+        } /* end if */
+        else /* Deleted last node at top level of tree */
+            *root=newp;
+    } /* end else */
+
+    H5FL_FREE(H5ST_node_t,p);
+
+    FUNC_LEAVE(SUCCEED);
+} /* end H5ST_delete_internal() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_delete
+ PURPOSE
+    Delete a node from a TST
+ USAGE
+    herr_t H5ST_delete(tree,p)
+        H5ST_tree_t *tree;  IN/OUT: TST to delete node from
+        H5ST_ptr_t p;       IN: Node to delete
+ RETURNS
+    Success: Non-negative
+    Failure: Negative
+ DESCRIPTION
+    Delete a node from a TST.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+    This should be the final node for a string.
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5ST_delete(H5ST_tree_t *tree, H5ST_ptr_t p)
+{   
+    herr_t ret_value=SUCCEED;   /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_delete,FAIL);
+
+    if(H5ST_delete_internal(&tree->root,p)<0)
+        HGOTO_ERROR(H5E_TST,H5E_CANTDELETE,FAIL,"can't delete node from TST");
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_delete() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_remove
+ PURPOSE
+    Remove a node from a TST
+ USAGE
+    void *H5ST_remove(tree,s)
+        H5ST_tree_t *tree;  IN/OUT: TST to remove node from
+        const char *s;      IN: String of key for node to remove
+ RETURNS
+    Success: Non-NULL, pointer to object stored for key
+    Failure: Negative
+ DESCRIPTION
+    Remove a node from a TST, returning the object from the node.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+void *
+H5ST_remove(H5ST_tree_t *tree, const char *s)
+{
+    H5ST_ptr_t node;    /* Pointer to node to remove */
+    void *ret_value;    /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_remove,NULL);
+
+    /* Locate the node to remove */
+    if((node=H5ST_find_internal(tree->root,s))==NULL)
+        HGOTO_ERROR(H5E_TST,H5E_NOTFOUND,NULL,"key not found in TST");
+
+    /* Get the pointer to the object to return */
+    ret_value=node->eqkid;
+
+    /* Remove the node from the TST */
+    if(H5ST_delete_internal(&tree->root,node)<0)
+        HGOTO_ERROR(H5E_TST,H5E_CANTDELETE,NULL,"can't delete node from TST");
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* H5ST_remove() */
+
+#ifdef H5ST_DEBUG
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_dump_internal
+ PURPOSE
+    Dump all the nodes of a TST
+ USAGE
+    herr_t H5ST_dump(p)
+        H5ST_ptr_t p;   IN: Root of TST to dump
+ RETURNS
+    Success: Non-negative
+    Failure: Negative
+ DESCRIPTION
+    Dump information for a TST.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5ST_dump_internal(H5ST_ptr_t p)
+{
+    FUNC_ENTER_NOINIT(H5ST_dump_internal);
+
+    if (p) {
+        printf("p=%p\n",p);
+        printf("\tp->up=%p\n",p->up);
+        printf("\tp->parent=%p\n",p->parent);
+        printf("\tp->lokid=%p\n",p->lokid);
+        printf("\tp->hikid=%p\n",p->hikid);
+        printf("\tp->eqkid=%p\n",p->eqkid);
+        printf("\tp->splitchar=%c\n",p->splitchar);
+
+        H5ST_dump_internal(p->lokid);
+        if (p->splitchar)
+            H5ST_dump_internal(p->eqkid);
+        else
+            printf("%s\n", (char *) p->eqkid);
+        H5ST_dump_internal(p->hikid);
+    } /* end if */
+
+done:
+    FUNC_LEAVE(SUCCEED);
+} /* end H5ST_dump_internal() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
+    H5ST_dump
+ PURPOSE
+    Dump all the nodes of a TST
+ USAGE
+    herr_t H5ST_dump(tree)
+        H5ST_tree_t *tree;      IN: TST to dump
+ RETURNS
+    Success: Non-negative
+    Failure: Negative
+ DESCRIPTION
+    Dump information for a TST.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+herr_t
+H5ST_dump(H5ST_tree_t *tree)
+{
+    herr_t ret_value=SUCCEED;  /* Return value */
+
+    FUNC_ENTER_NOAPI(H5ST_dump,NULL);
+
+    /* Dump the tree */
+    H5ST_dump_internal(tree->root);
+
+done:
+    FUNC_LEAVE(ret_value);
+} /* end H5ST_dump() */
+#endif /* H5ST_DEBUG */
diff --git a/src/H5STprivate.h b/src/H5STprivate.h
new file mode 100644
index 0000000..60452a6
--- /dev/null
+++ b/src/H5STprivate.h
@@ -0,0 +1,61 @@
+/****************************************************************************
+ * NCSA HDF								    *
+ * Software Development Group						    *
+ * National Center for Supercomputing Applications			    *
+ * University of Illinois at Urbana-Champaign				    *
+ * 605 E. Springfield, Champaign IL 61820				    *
+ *									    *
+ * For conditions of distribution and use, see the accompanying		    *
+ * hdf/COPYING file.							    *
+ *									    *
+ ****************************************************************************/
+
+/*
+ * This file contains private information about the H5ST module
+ */
+#ifndef _H5STprivate_H
+#define _H5STprivate_H
+
+#ifdef LATER
+#include "H5STpublic.h"
+#endif /* LATER */
+
+/* Private headers needed by this file */
+#include "H5private.h"
+
+/* Typedefs */
+
+/* Internal nodes for TST */
+typedef struct H5ST_node *H5ST_ptr_t;
+typedef struct H5ST_node {
+    char splitchar;             /* Character represented at node */
+    H5ST_ptr_t up;              /* Pointer to the node in the tree above (before) this node */
+    H5ST_ptr_t parent;          /* Pointer to the next higher tree node in this tree */
+    H5ST_ptr_t lokid;           /* Pointer to the lower node from this one, in this tree */
+    H5ST_ptr_t eqkid;           /* Pointer to the parent node in the next tree down (after) this node */
+    H5ST_ptr_t hikid;           /* Pointer to the higher node from this one, in this tree */
+} H5ST_node_t;
+
+/* Wrapper about TST */
+typedef struct {
+    H5ST_ptr_t root;            /* Pointer to actual TST */
+} H5ST_tree_t;
+
+/* Macro to access "data" pointer in H5ST_node_t's returned from functions */
+#define H5ST_NODE_DATA(p)       ((void *)(p->eqkid))
+
+/* Private routines */
+H5_DLL H5ST_tree_t *H5ST_create(void);
+H5_DLL herr_t H5ST_close(H5ST_tree_t *p);
+H5_DLL herr_t H5ST_insert(H5ST_tree_t *root, const char *s, void *obj);
+H5_DLL htri_t H5ST_search(H5ST_tree_t *root, const char *s);
+H5_DLL H5ST_ptr_t H5ST_find(H5ST_tree_t *root, const char *s);
+H5_DLL void *H5ST_locate(H5ST_tree_t *root, const char *s);
+H5_DLL H5ST_ptr_t H5ST_findfirst(H5ST_tree_t *p);
+H5_DLL H5ST_ptr_t H5ST_findnext(H5ST_ptr_t p);
+H5_DLL void *H5ST_remove(H5ST_tree_t *root, const char *s);
+H5_DLL herr_t H5ST_delete(H5ST_tree_t *root, H5ST_ptr_t p);
+H5_DLL herr_t H5ST_dump(H5ST_ptr_t p);
+
+#endif /* _H5STprivate_H */
+
diff --git a/src/H5Sall.c b/src/H5Sall.c
index ab12d70..8bab11c 100644
--- a/src/H5Sall.c
+++ b/src/H5Sall.c
@@ -175,7 +175,6 @@ done:
 hsize_t
 H5S_all_npoints (const H5S_t *space)
 {
-    unsigned u;     /* Counters */
     hsize_t ret_value;
 
     FUNC_ENTER_NOAPI(H5S_all_npoints, 0);
@@ -183,8 +182,7 @@ H5S_all_npoints (const H5S_t *space)
     /* Check args */
     assert (space);
 
-    for(u=0, ret_value=1; u<space->extent.u.simple.rank; u++)
-        ret_value*=space->extent.u.simple.size[u];
+    ret_value=(hsize_t)H5S_get_simple_extent_npoints(space);
     
 done:
     FUNC_LEAVE (ret_value);
diff --git a/src/H5Shyper.c b/src/H5Shyper.c
index 3eec64e..994238f 100644
--- a/src/H5Shyper.c
+++ b/src/H5Shyper.c
@@ -156,10 +156,14 @@ H5S_hyper_iter_init (const H5S_t *space, size_t elmt_size, H5S_sel_iter_t *sel_i
             sel_iter->hyp.iter_rank=cont_dim;
 
             /* Allocate the position & initialize to initial location */
-            sel_iter->hyp.off = H5FL_ARR_ALLOC(hsize_t,cont_dim,0);
-            sel_iter->hyp.diminfo = H5FL_ARR_ALLOC(H5S_hyper_dim_t,cont_dim,0);
-            sel_iter->hyp.size = H5FL_ARR_ALLOC(hsize_t,cont_dim,0);
-            sel_iter->hyp.sel_off = H5FL_ARR_ALLOC(hssize_t,cont_dim,0);
+            sel_iter->hyp.off = H5FL_ARR_MALLOC(hsize_t,cont_dim);
+            assert(sel_iter->hyp.off);
+            sel_iter->hyp.diminfo = H5FL_ARR_MALLOC(H5S_hyper_dim_t,cont_dim);
+            assert(sel_iter->hyp.diminfo);
+            sel_iter->hyp.size = H5FL_ARR_MALLOC(hsize_t,cont_dim);
+            assert(sel_iter->hyp.size);
+            sel_iter->hyp.sel_off = H5FL_ARR_MALLOC(hssize_t,cont_dim);
+            assert(sel_iter->hyp.sel_off);
 
             /* "Flatten" dataspace extent and selection information */
             for(i=space->extent.u.simple.rank-1, acc=1; i>=0; i--) {
@@ -197,10 +201,20 @@ H5S_hyper_iter_init (const H5S_t *space, size_t elmt_size, H5S_sel_iter_t *sel_i
         } /* end if */
         else {
             /* Allocate the position & initialize to initial location */
-            sel_iter->hyp.off = H5FL_ARR_ALLOC(hsize_t,space->extent.u.simple.rank,0);
+            sel_iter->hyp.off = H5FL_ARR_MALLOC(hsize_t,space->extent.u.simple.rank);
+            assert(sel_iter->hyp.off);
             for(u=0; u<space->extent.u.simple.rank; u++)
                 sel_iter->hyp.off[u]=tdiminfo[u].start;
+
+            /* Initialize other regular region information also (for release) */
+            sel_iter->hyp.diminfo = NULL;
+            sel_iter->hyp.size = NULL;
+            sel_iter->hyp.sel_off = NULL;
         } /* end else */
+
+        /* Initialize irregular region information also (for release) */
+        sel_iter->hyp.spans=NULL;
+        sel_iter->hyp.span=NULL;
     } /* end if */
     else {
 /* Initialize the information needed for non-regular hyperslab I/O */
@@ -211,8 +225,10 @@ H5S_hyper_iter_init (const H5S_t *space, size_t elmt_size, H5S_sel_iter_t *sel_i
         H5S_hyper_span_precompute(sel_iter->hyp.spans,elmt_size);
 
         /* Allocate the span tree pointers, span pointers and positions */
-        sel_iter->hyp.span = H5FL_ARR_ALLOC(H5S_hyper_span_t,space->extent.u.simple.rank,0);
-        sel_iter->hyp.off = H5FL_ARR_ALLOC(hsize_t,space->extent.u.simple.rank,0);
+        sel_iter->hyp.span = H5FL_ARR_MALLOC(H5S_hyper_span_t,space->extent.u.simple.rank);
+        assert(sel_iter->hyp.span);
+        sel_iter->hyp.off = H5FL_ARR_MALLOC(hsize_t,space->extent.u.simple.rank);
+        assert(sel_iter->hyp.off);
 
         /* Initialize the starting span_info's and spans */
         spans=sel_iter->hyp.spans;
@@ -230,6 +246,11 @@ H5S_hyper_iter_init (const H5S_t *space, size_t elmt_size, H5S_sel_iter_t *sel_i
             /* Get the pointer to the next level down */
             spans=spans->head->down;
         } /* end for */
+
+        /* Initialize regular region information also (for release) */
+        sel_iter->hyp.diminfo = NULL;
+        sel_iter->hyp.size = NULL;
+        sel_iter->hyp.sel_off = NULL;
     } /* end else */
 
 done:
@@ -499,7 +520,7 @@ H5S_hyper_new_span (hssize_t low, hssize_t high, H5S_hyper_span_info_t *down, H5
     FUNC_ENTER_NOINIT(H5S_hyper_new_span);
 
     /* Allocate a new span node */
-    if((ret_value = H5FL_ALLOC(H5S_hyper_span_t,0))==NULL)
+    if((ret_value = H5FL_MALLOC(H5S_hyper_span_t))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span");
        
     /* Copy the span's basic information */
@@ -710,7 +731,7 @@ H5S_hyper_copy_span_helper (H5S_hyper_span_info_t *spans)
     } /* end if */
     else {
         /* Allocate a new span_info node */
-        if((ret_value = H5FL_ALLOC(H5S_hyper_span_info_t,0))==NULL)
+        if((ret_value = H5FL_MALLOC(H5S_hyper_span_info_t))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span");
            
         /* Copy the span_info information */
@@ -1033,7 +1054,7 @@ H5S_hyper_copy (H5S_t *dst, const H5S_t *src)
     /* Check if there is regular hyperslab information to copy */
     if(src->select.sel_info.hslab.diminfo!=NULL) {
         /* Create the per-dimension selection info */
-        if((new_diminfo = H5FL_ARR_ALLOC(H5S_hyper_dim_t,src->extent.u.simple.rank,0))==NULL)
+        if((new_diminfo = H5FL_ARR_MALLOC(H5S_hyper_dim_t,src->extent.u.simple.rank))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate per-dimension array");
 
         /* Copy the per-dimension selection info */
@@ -1046,7 +1067,7 @@ H5S_hyper_copy (H5S_t *dst, const H5S_t *src)
         dst->select.sel_info.hslab.diminfo = new_diminfo;
 
         /* Create the per-dimension selection info */
-        if((new_diminfo = H5FL_ARR_ALLOC(H5S_hyper_dim_t,src->extent.u.simple.rank,0))==NULL)
+        if((new_diminfo = H5FL_ARR_MALLOC(H5S_hyper_dim_t,src->extent.u.simple.rank))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate per-dimension array");
 
         /* Copy the per-dimension selection info */
@@ -1676,13 +1697,13 @@ H5S_hyper_deserialize (H5S_t *space, const uint8_t *buf)
     UINT32DECODE(buf,num_elem);  /* decode the number of points */
 
     /* Allocate space for the coordinates */
-    if((start = H5FL_ARR_ALLOC(hsize_t,rank,0))==NULL)
+    if((start = H5FL_ARR_MALLOC(hsize_t,rank))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab information");
-    if((end = H5FL_ARR_ALLOC(hsize_t,rank,0))==NULL)
+    if((end = H5FL_ARR_MALLOC(hsize_t,rank))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab information");
-    if((block = H5FL_ARR_ALLOC(hsize_t,rank,0))==NULL)
+    if((block = H5FL_ARR_MALLOC(hsize_t,rank))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab information");
-    if((count = H5FL_ARR_ALLOC(hsize_t,rank,0))==NULL)
+    if((count = H5FL_ARR_MALLOC(hsize_t,rank))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab information");
     
     /* Set the count for all blocks */
@@ -2603,7 +2624,7 @@ H5S_hyper_append_span (H5S_hyper_span_t **prev_span, H5S_hyper_span_info_t ** sp
         assert(*span_tree==NULL);
 
         /* Allocate a new span_info node */
-        if((*span_tree = H5FL_ALLOC(H5S_hyper_span_info_t,0))==NULL)
+        if((*span_tree = H5FL_MALLOC(H5S_hyper_span_info_t))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate hyperslab span");
            
         /* Set the span tree's basic information */
@@ -3631,7 +3652,7 @@ H5S_hyper_make_spans (unsigned rank, const hssize_t *start, const hsize_t *strid
         /* Generate all the spans segments for this dimension */
         for(u=0; u<count[i]; u++) {
             /* Allocate a span node */
-            if((span = H5FL_ALLOC(H5S_hyper_span_t,0))==NULL)
+            if((span = H5FL_MALLOC(H5S_hyper_span_t))==NULL)
                 HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span");
 
             /* Set the span's basic information */
@@ -3661,7 +3682,7 @@ H5S_hyper_make_spans (unsigned rank, const hssize_t *start, const hsize_t *strid
         } /* end for */
 
         /* Allocate a span info node */
-        if((down = H5FL_ALLOC(H5S_hyper_span_info_t,0))==NULL)
+        if((down = H5FL_MALLOC(H5S_hyper_span_info_t))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "can't allocate hyperslab span");
 
         /* Set the reference count */
@@ -3931,7 +3952,7 @@ H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
         hssize_t fill=1;
 
         /* Allocate temporary buffer */
-        if ((_stride=H5FL_ARR_ALLOC(hsize_t,space->extent.u.simple.rank,0))==NULL)
+        if ((_stride=H5FL_ARR_MALLOC(hsize_t,space->extent.u.simple.rank))==NULL)
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for stride buffer");
         H5V_array_fill(_stride,&fill,sizeof(hssize_t),space->extent.u.simple.rank);
         stride = _stride;
@@ -3942,7 +3963,7 @@ H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
         hssize_t fill=1;
 
         /* Allocate temporary buffer */
-        if ((_block=H5FL_ARR_ALLOC(hsize_t,space->extent.u.simple.rank,0))==NULL)
+        if ((_block=H5FL_ARR_MALLOC(hsize_t,space->extent.u.simple.rank))==NULL)
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for stride buffer");
         H5V_array_fill(_block,&fill,sizeof(hssize_t),space->extent.u.simple.rank);
         block = _block;
@@ -4046,7 +4067,7 @@ H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
             HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't release hyperslab");
 
         /* Copy all the application per-dimension selection info into the space descriptor */
-        if((diminfo = H5FL_ARR_ALLOC(H5S_hyper_dim_t,space->extent.u.simple.rank,0))==NULL)
+        if((diminfo = H5FL_ARR_MALLOC(H5S_hyper_dim_t,space->extent.u.simple.rank))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate per-dimension vector");
         for(u=0; u<space->extent.u.simple.rank; u++) {
             diminfo[u].start = start[u];
@@ -4057,7 +4078,7 @@ H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
         space->select.sel_info.hslab.app_diminfo = diminfo;
 
         /* Allocate room for the optimized per-dimension selection info */
-        if((diminfo = H5FL_ARR_ALLOC(H5S_hyper_dim_t,space->extent.u.simple.rank,0))==NULL)
+        if((diminfo = H5FL_ARR_MALLOC(H5S_hyper_dim_t,space->extent.u.simple.rank))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate per-dimension vector");
 
         /* Optimize the hyperslab selection to detect contiguously selected block/stride information */
@@ -4479,7 +4500,7 @@ H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
         hssize_t fill=1;
 
         /* Allocate temporary buffer */
-        if ((_stride=H5FL_ARR_ALLOC(hsize_t,space->extent.u.simple.rank,0))==NULL)
+        if ((_stride=H5FL_ARR_MALLOC(hsize_t,space->extent.u.simple.rank))==NULL)
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for stride buffer");
         H5V_array_fill(_stride,&fill,sizeof(hssize_t),space->extent.u.simple.rank);
         stride = _stride;
@@ -4490,7 +4511,7 @@ H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
         hssize_t fill=1;
 
         /* Allocate temporary buffer */
-        if ((_block=H5FL_ARR_ALLOC(hsize_t,space->extent.u.simple.rank,0))==NULL)
+        if ((_block=H5FL_ARR_MALLOC(hsize_t,space->extent.u.simple.rank))==NULL)
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for stride buffer");
         H5V_array_fill(_block,&fill,sizeof(hssize_t),space->extent.u.simple.rank);
         block = _block;
@@ -4595,7 +4616,7 @@ H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
             HGOTO_ERROR(H5E_DATASPACE, H5E_CANTDELETE, FAIL, "can't release hyperslab");
 
         /* Copy all the application per-dimension selection info into the space descriptor */
-        if((diminfo = H5FL_ARR_ALLOC(H5S_hyper_dim_t,space->extent.u.simple.rank,0))==NULL)
+        if((diminfo = H5FL_ARR_MALLOC(H5S_hyper_dim_t,space->extent.u.simple.rank))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate per-dimension vector");
         for(u=0; u<space->extent.u.simple.rank; u++) {
             diminfo[u].start = start[u];
@@ -4606,7 +4627,7 @@ H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op,
         space->select.sel_info.hslab.app_diminfo = diminfo;
 
         /* Allocate room for the optimized per-dimension selection info */
-        if((diminfo = H5FL_ARR_ALLOC(H5S_hyper_dim_t,space->extent.u.simple.rank,0))==NULL)
+        if((diminfo = H5FL_ARR_MALLOC(H5S_hyper_dim_t,space->extent.u.simple.rank))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate per-dimension vector");
 
         /* Optimize the hyperslab selection to detect contiguously selected block/stride information */
diff --git a/src/H5Smpio.c b/src/H5Smpio.c
index 9b3f132..1fc2ea9 100644
--- a/src/H5Smpio.c
+++ b/src/H5Smpio.c
@@ -950,9 +950,9 @@ done:
  */
 herr_t
 H5S_mpio_spaces_read(H5F_t *f, const H5O_layout_t *layout,
-                    H5P_genplist_t UNUSED *dc_plist, size_t elmt_size,
-                    const H5S_t *file_space, const H5S_t *mem_space,
-                    hid_t dxpl_id, void *buf/*out*/)
+    H5P_genplist_t UNUSED *dc_plist, const H5O_efl_t UNUSED *efl, size_t elmt_size,
+    const H5S_t *file_space, const H5S_t *mem_space, hid_t dxpl_id,
+    void *buf/*out*/)
 {
     herr_t ret_value;
 
@@ -989,9 +989,9 @@ done:
  */
 herr_t
 H5S_mpio_spaces_write(H5F_t *f, H5O_layout_t *layout,
-                    H5P_genplist_t UNUSED *dc_plist, size_t elmt_size,
-		    const H5S_t *file_space, const H5S_t *mem_space,
-		    hid_t dxpl_id, const void *buf)
+    H5P_genplist_t UNUSED *dc_plist, const H5O_efl_t UNUSED *efl, size_t elmt_size,
+    const H5S_t *file_space, const H5S_t *mem_space, hid_t dxpl_id,
+    const void *buf)
 {
     herr_t ret_value;
 
diff --git a/src/H5Spkg.h b/src/H5Spkg.h
index 97b5052..fc74733 100644
--- a/src/H5Spkg.h
+++ b/src/H5Spkg.h
@@ -33,7 +33,8 @@ typedef struct H5S_simple_t {
 
 /* Extent container */
 typedef struct {
-    H5S_class_t	type;		    /* Type of extent */
+    H5S_class_t	type;   /* Type of extent */
+    hsize_t nelem;      /* Number of elements in extent */
     union {
         H5S_simple_t	simple;	/* Simple dimensionality information  */
     } u;
diff --git a/src/H5Spoint.c b/src/H5Spoint.c
index 14d30d4..0072c15 100644
--- a/src/H5Spoint.c
+++ b/src/H5Spoint.c
@@ -167,7 +167,7 @@ H5S_point_add (H5S_t *space, H5S_seloper_t op, size_t num_elem, const hssize_t *
     top=curr=NULL;
     for(i=0; i<num_elem; i++) {
         /* Allocate space for the new node */
-        if((new_node = H5FL_ALLOC(H5S_pnt_node_t,0))==NULL)
+        if((new_node = H5FL_MALLOC(H5S_pnt_node_t))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate point node");
 
         if((new_node->pnt = H5MM_malloc(space->extent.u.simple.rank*sizeof(hssize_t)))==NULL)
@@ -350,7 +350,7 @@ H5S_select_elements (H5S_t *space, H5S_seloper_t op, size_t num_elem,
 
     /* Allocate space for the point selection information if necessary */
     if(space->select.type!=H5S_SEL_POINTS || space->select.sel_info.pnt_lst==NULL) {
-        if((space->select.sel_info.pnt_lst = H5FL_ALLOC(H5S_pnt_list_t,1))==NULL)
+        if((space->select.sel_info.pnt_lst = H5FL_CALLOC(H5S_pnt_list_t))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate element information");
     } /* end if */
 
@@ -412,14 +412,14 @@ H5S_point_copy (H5S_t *dst, const H5S_t *src)
     assert(dst);
 
     /* Allocate room for the head of the point list */
-    if((dst->select.sel_info.pnt_lst=H5FL_ALLOC(H5S_pnt_list_t,0))==NULL)
+    if((dst->select.sel_info.pnt_lst=H5FL_MALLOC(H5S_pnt_list_t))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate point node");
 
     curr=src->select.sel_info.pnt_lst->head;
     new_head=NULL;
     while(curr!=NULL) {
         /* Create each point */
-        if((new_node=H5FL_ALLOC(H5S_pnt_node_t,0))==NULL)
+        if((new_node=H5FL_MALLOC(H5S_pnt_node_t))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate point node");
         if((new_node->pnt = H5MM_malloc(src->extent.u.simple.rank*sizeof(hssize_t)))==NULL)
             HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate coordinate information");
diff --git a/src/H5Sprivate.h b/src/H5Sprivate.h
index 1daaf04..0c267ac 100644
--- a/src/H5Sprivate.h
+++ b/src/H5Sprivate.h
@@ -103,16 +103,16 @@ typedef struct H5S_conv_t {
     
     /* Read from file to application w/o intermediate scratch buffer */
     herr_t (*read)(H5F_t *f, const struct H5O_layout_t *layout,
-                   H5P_genplist_t *dc_plist, size_t elmt_size,
-		   const H5S_t *file_space, const H5S_t *mem_space,
-		   hid_t dxpl_id, void *buf/*out*/);
+           H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
+           size_t elmt_size, const H5S_t *file_space,
+           const H5S_t *mem_space, hid_t dxpl_id, void *buf/*out*/);
 
 
     /* Write directly from app buffer to file */
     herr_t (*write)(H5F_t *f, struct H5O_layout_t *layout,
-                   H5P_genplist_t *dc_plist, size_t elmt_size,
-		   const H5S_t *file_space, const H5S_t *mem_space,
-		   hid_t dxpl_id, const void *buf);
+           H5P_genplist_t *dc_plist, const H5O_efl_t *efl,
+           size_t elmt_size, const H5S_t *file_space,
+           const H5S_t *mem_space, hid_t dxpl_id, const void *buf);
     
 #ifdef H5S_DEBUG
     struct {
@@ -150,7 +150,9 @@ H5_DLL int H5S_get_simple_extent_dims(const H5S_t *ds, hsize_t dims[]/*out*/,
 					hsize_t max_dims[]/*out*/);
 H5_DLL herr_t H5S_set_extent_simple (H5S_t *space, unsigned rank, const hsize_t *dims,
 		       const hsize_t *max);
-H5_DLL herr_t H5S_modify(struct H5G_entry_t *ent, const H5S_t *space);
+H5_DLL herr_t H5S_modify(struct H5G_entry_t *ent, const H5S_t *space,
+        hbool_t update_time);
+H5_DLL herr_t H5S_append(H5F_t *f, H5O_t *oh, const H5S_t *ds);
 H5_DLL H5S_t *H5S_read(struct H5G_entry_t *ent);
 H5_DLL int H5S_cmp(const H5S_t *ds1, const H5S_t *ds2);
 H5_DLL htri_t H5S_is_simple(const H5S_t *sdim);
@@ -169,13 +171,13 @@ H5_DLL herr_t H5S_select_iterate(void *buf, hid_t type_id, H5S_t *space,
 H5_DLL herr_t H5S_select_fill(void *fill, size_t fill_size,
                                 const H5S_t *space, void *buf);
 H5_DLL herr_t H5S_select_fscat (H5F_t *f, struct H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist, size_t elmt_size, const H5S_t *file_space,
-        H5S_sel_iter_t *file_iter, hsize_t nelmts, hid_t dxpl_id,
-        const void *_buf);
+        H5P_genplist_t *dc_plist, const H5O_efl_t *efl, size_t elmt_size,
+        const H5S_t *file_space, H5S_sel_iter_t *file_iter, hsize_t nelmts,
+        hid_t dxpl_id, const void *_buf);
 H5_DLL hsize_t H5S_select_fgath (H5F_t *f, const struct H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist, size_t elmt_size, const H5S_t *file_space,
-        H5S_sel_iter_t *file_iter, hsize_t nelmts, hid_t dxpl_id,
-        void *buf);
+        H5P_genplist_t *dc_plist, const H5O_efl_t *efl, size_t elmt_size,
+        const H5S_t *file_space, H5S_sel_iter_t *file_iter, hsize_t nelmts,
+        hid_t dxpl_id, void *buf);
 H5_DLL herr_t H5S_select_mscat (const void *_tscat_buf, size_t elmt_size,
         const H5S_t *space, H5S_sel_iter_t *iter, hsize_t nelmts,
         hid_t dxpl_id, void *_buf/*out*/);
@@ -183,11 +185,13 @@ H5_DLL hsize_t H5S_select_mgath (const void *_buf, size_t elmt_size,
         const H5S_t *space, H5S_sel_iter_t *iter, hsize_t nelmts,
         hid_t dxpl_id, void *_tgath_buf/*out*/);
 H5_DLL herr_t H5S_select_read(H5F_t *f, const struct H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist, size_t elmt_size, const H5S_t *file_space,
-        const H5S_t *mem_space, hid_t dxpl_id, void *buf/*out*/);
+        H5P_genplist_t *dc_plist, const H5O_efl_t *efl, size_t elmt_size,
+        const H5S_t *file_space, const H5S_t *mem_space, hid_t dxpl_id,
+        void *buf/*out*/);
 H5_DLL herr_t H5S_select_write(H5F_t *f, struct H5O_layout_t *layout,
-        H5P_genplist_t *dc_plist, size_t elmt_size, const H5S_t *file_space,
-        const H5S_t *mem_space, hid_t dxpl_id, const void *buf/*out*/);
+        H5P_genplist_t *dc_plist, const H5O_efl_t *efl, size_t elmt_size,
+        const H5S_t *file_space, const H5S_t *mem_space, hid_t dxpl_id,
+        const void *buf/*out*/);
 
 /* Needed for internal use of selections in H5Fistore code */
 H5_DLL herr_t H5S_select_all(H5S_t *space, unsigned rel_prev);
@@ -200,6 +204,7 @@ H5_DLL herr_t H5S_select_hyperslab (H5S_t *space, H5S_seloper_t op, const hssize
 H5_DLL herr_t H5S_mpio_spaces_read(H5F_t *f,
 				    const struct H5O_layout_t *layout,
                                     H5P_genplist_t *dc_plist,
+                                    const H5O_efl_t *efl,
 				    size_t elmt_size, const H5S_t *file_space,
 				    const H5S_t *mem_space, hid_t dxpl_id,
 				    void *buf/*out*/);
@@ -208,6 +213,7 @@ H5_DLL herr_t H5S_mpio_spaces_read(H5F_t *f,
 H5_DLL herr_t H5S_mpio_spaces_write(H5F_t *f,
 				    struct H5O_layout_t *layout,
                                     H5P_genplist_t *dc_plist,
+                                    const H5O_efl_t *efl,
 				    size_t elmt_size, const H5S_t *file_space,
 				    const H5S_t *mem_space, hid_t dxpl_id,
 				    const void *buf);
diff --git a/src/H5Sselect.c b/src/H5Sselect.c
index 0fb429e..edc8fa7 100644
--- a/src/H5Sselect.c
+++ b/src/H5Sselect.c
@@ -32,15 +32,56 @@ H5FL_ARR_DEFINE_STATIC(size_t,-1);
 /* Declare a free list to manage arrays of hsize_t */
 H5FL_ARR_DEFINE_STATIC(hsize_t,-1);
 
-/* Declare a free list to manage the H5S_sel_iter_t struct */
-H5FL_DEFINE_STATIC(H5S_sel_iter_t);
-
 /* Declare a free list to manage blocks of single datatype element data */
 H5FL_BLK_EXTERN(type_elem);
 
 
 /*--------------------------------------------------------------------------
  NAME
+    H5S_get_vector_size
+ PURPOSE
+    Gets the size of the I/O vector
+ USAGE
+    ssize_t H5S_get_vector_size(dxpl_id)
+        hid_t dxpl_id;          IN: The dataset transfer property list to query
+ RETURNS
+    Non-negative number of entries in I/O vector on success, negative on failure
+ DESCRIPTION
+    Retrieves the number of I/O vector entries to use for a given dataset
+    transfer.  If the default dataset property list is used, the default
+    number of I/O vectors is returned.
+ GLOBAL VARIABLES
+ COMMENTS, BUGS, ASSUMPTIONS
+ EXAMPLES
+ REVISION LOG
+--------------------------------------------------------------------------*/
+static ssize_t
+H5S_get_vector_size(hid_t dxpl_id)
+{
+    ssize_t ret_value;        /* return value */
+
+    FUNC_ENTER_NOINIT(H5S_get_vector_size);
+
+    if(dxpl_id==H5P_DATASET_XFER_DEFAULT) {
+        ret_value=H5D_XFER_HYPER_VECTOR_SIZE_DEF;
+    } /* end if */
+    else {
+        H5P_genplist_t *dx_plist;   /* Dataset transfer property list */
+
+        /* Get the hyperslab vector size */
+        if(NULL == (dx_plist = H5I_object(dxpl_id)))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list");
+        if (H5P_get(dx_plist,H5D_XFER_HYPER_VECTOR_SIZE_NAME,&ret_value)<0)
+            HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get value");
+    } /* end else */
+
+done:
+    FUNC_LEAVE (ret_value);
+}   /* H5S_get_vector_size() */
+
+
+/*--------------------------------------------------------------------------
+ NAME
     H5S_select_copy
  PURPOSE
     Copy a selection from one dataspace to another
@@ -75,7 +116,7 @@ H5S_select_copy (H5S_t *dst, const H5S_t *src)
 /* Need to copy order information still */
 
     /* Copy offset information */
-    if (NULL==(dst->select.offset = H5FL_ARR_ALLOC(hssize_t,src->extent.u.simple.rank,1)))
+    if (NULL==(dst->select.offset = H5FL_ARR_CALLOC(hssize_t,src->extent.u.simple.rank)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
     if(src->select.offset!=NULL)
         HDmemcpy(dst->select.offset,src->select.offset,(src->extent.u.simple.rank*sizeof(hssize_t)));
@@ -342,8 +383,8 @@ H5S_select_iterate(void *buf, hid_t type_id, H5S_t *space, H5D_operator_t op,
         void *operator_data)
 {
     H5T_t *dt;                  /* Datatype structure */
-    H5P_genplist_t *dx_plist;   /* Dataset transfer property list */
-    H5S_sel_iter_t *iter=NULL;  /* Selection iteration info */
+    H5S_sel_iter_t iter;        /* Selection iteration info */
+    hbool_t iter_init=0;        /* Selection iteration info has been initialized */
     uint8_t *loc;               /* Current element location in buffer */
     hssize_t coords[H5O_LAYOUT_NDIMS];  /* Coordinates of element in dataspace */
     hssize_t nelmts;            /* Number of elements in selection */
@@ -353,7 +394,7 @@ H5S_select_iterate(void *buf, hid_t type_id, H5S_t *space, H5D_operator_t op,
     hsize_t tmp_off;            /* Temporary offset within sequence */
     size_t *len=NULL;           /* Array to store sequence lengths */
     size_t curr_len;            /* Length of bytes left to process in sequence */
-    size_t vector_size;         /* Value for vector size */
+    ssize_t vector_size;        /* Value for vector size */
     size_t nseq;                /* Number of sequences generated */
     size_t curr_seq;            /* Current sequnce being worked on */
     size_t nbytes;              /* Number of bytes used in sequences */
@@ -374,15 +415,13 @@ H5S_select_iterate(void *buf, hid_t type_id, H5S_t *space, H5D_operator_t op,
 
     /* Get the hyperslab vector size */
     /* (from the default data transfer property list, for now) */
-    dx_plist = H5I_object(H5P_DATASET_XFER_DEFAULT);
-    assert(dx_plist);
-    if (H5P_get(dx_plist,H5D_XFER_HYPER_VECTOR_SIZE_NAME,&vector_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get value");
+    if((vector_size=H5S_get_vector_size(H5P_DATASET_XFER_DEFAULT))<0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get I/O vector size");
 
     /* Allocate the vector I/O arrays */
-    if((len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O length vector array");
-    if((off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O offset vector array");
 
     /* Get the datatype size */
@@ -391,13 +430,10 @@ H5S_select_iterate(void *buf, hid_t type_id, H5S_t *space, H5D_operator_t op,
     if((elmt_size=H5T_get_size(dt))==0)
         HGOTO_ERROR(H5E_DATATYPE, H5E_BADSIZE, FAIL, "datatype size invalid");
 
-    /* Allocate iterator */
-    if((iter = H5FL_ALLOC(H5S_sel_iter_t,1))==NULL)
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate selection iterator");
-
     /* Initialize iterator */
-    if ((*space->select.iter_init)(space, elmt_size, iter)<0)
+    if ((*space->select.iter_init)(space, elmt_size, &iter)<0)
         HGOTO_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to initialize selection iterator");
+    iter_init=1;	/* Selection iteration info has been initialized */
 
     /* Get the number of elements in selection */
     if((nelmts = (*space->select.get_npoints)(space))<0)
@@ -419,7 +455,7 @@ H5S_select_iterate(void *buf, hid_t type_id, H5S_t *space, H5D_operator_t op,
     /* Loop, while elements left in selection */
     while(max_bytes>0 && user_ret==0) {
         /* Get the sequences of bytes */
-        if((*space->select.get_seq_list)(space,0,iter,elmt_size,vector_size,max_bytes,&nseq,&nbytes,off,len)<0)
+        if((*space->select.get_seq_list)(space,0,&iter,elmt_size,(size_t)vector_size,max_bytes,&nseq,&nbytes,off,len)<0)
             HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, FAIL, "sequence length generation failed");
 
         /* Loop, while sequences left to process */
@@ -462,10 +498,9 @@ H5S_select_iterate(void *buf, hid_t type_id, H5S_t *space, H5D_operator_t op,
 
 done:
     /* Release selection iterator */
-    if(iter!=NULL) {
-        if ((*space->select.iter_release)(iter)<0)
-            HGOTO_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
-	H5FL_FREE(H5S_sel_iter_t,iter);
+    if(iter_init) {
+        if ((*space->select.iter_release)(&iter)<0)
+            HDONE_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
     } /* end if */
 
     /* Release length & offset vectors */
@@ -661,14 +696,14 @@ done:
 herr_t
 H5S_select_fill(void *_fill, size_t fill_size, const H5S_t *space, void *_buf)
 {
-    H5P_genplist_t *dx_plist;   /* Dataset transfer property list */
-    H5S_sel_iter_t *iter=NULL;  /* Selection iteration info */
+    H5S_sel_iter_t iter;        /* Selection iteration info */
+    hbool_t iter_init=0;        /* Selection iteration info has been initialized */
     uint8_t *buf;               /* Current location in buffer */
     void *fill=_fill;           /* Alias for fill-value buffer */
     hssize_t nelmts;            /* Number of elements in selection */
     hsize_t *off=NULL;          /* Array to store sequence offsets */
     size_t *len=NULL;           /* Array to store sequence lengths */
-    size_t vector_size;         /* Value for vector size */
+    ssize_t vector_size;        /* Value for vector size */
     size_t nseq;                /* Number of sequences generated */
     size_t curr_seq;            /* Current sequnce being worked on */
     size_t nbytes;              /* Number of bytes used in sequences */
@@ -684,30 +719,25 @@ H5S_select_fill(void *_fill, size_t fill_size, const H5S_t *space, void *_buf)
 
     /* Check if we need a temporary fill value buffer */
     if(fill==NULL) {
-        if (NULL==(fill = H5FL_BLK_ALLOC(type_elem,fill_size,1)))
+        if (NULL==(fill = H5FL_BLK_CALLOC(type_elem,fill_size)))
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "fill value buffer allocation failed");
     } /* end if */
 
     /* Get the hyperslab vector size */
     /* (from the default data transfer property list, for now) */
-    dx_plist = H5I_object(H5P_DATASET_XFER_DEFAULT);
-    assert(dx_plist);
-    if (H5P_get(dx_plist,H5D_XFER_HYPER_VECTOR_SIZE_NAME,&vector_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get value");
+    if((vector_size=H5S_get_vector_size(H5P_DATASET_XFER_DEFAULT))<0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get I/O vector size");
 
     /* Allocate the vector I/O arrays */
-    if((len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O length vector array");
-    if((off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O offset vector array");
 
-    /* Allocate iterator */
-    if((iter = H5FL_ALLOC(H5S_sel_iter_t,1))==NULL)
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate selection iterator");
-
     /* Initialize iterator */
-    if ((*space->select.iter_init)(space, fill_size, iter)<0)
+    if ((*space->select.iter_init)(space, fill_size, &iter)<0)
         HGOTO_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to initialize selection iterator");
+    iter_init=1;	/* Selection iteration info has been initialized */
 
     /* Get the number of elements in selection */
     if((nelmts = (*space->select.get_npoints)(space))<0)
@@ -720,7 +750,7 @@ H5S_select_fill(void *_fill, size_t fill_size, const H5S_t *space, void *_buf)
     /* Loop, while elements left in selection */
     while(max_bytes>0) {
         /* Get the sequences of bytes */
-        if((*space->select.get_seq_list)(space,0,iter,fill_size,vector_size,max_bytes,&nseq,&nbytes,off,len)<0)
+        if((*space->select.get_seq_list)(space,0,&iter,fill_size,(size_t)vector_size,max_bytes,&nseq,&nbytes,off,len)<0)
             HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, FAIL, "sequence length generation failed");
 
         /* Loop over sequences */
@@ -739,10 +769,9 @@ H5S_select_fill(void *_fill, size_t fill_size, const H5S_t *space, void *_buf)
 
 done:
     /* Release selection iterator */
-    if(iter!=NULL) {
-        if ((*space->select.iter_release)(iter)<0)
-            HGOTO_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
-	H5FL_FREE(H5S_sel_iter_t,iter);
+    if(iter_init) {
+        if ((*space->select.iter_release)(&iter)<0)
+            HDONE_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
     } /* end if */
 
     /* Release length & offset vectors */
@@ -779,18 +808,17 @@ done:
  */
 herr_t
 H5S_select_fscat (H5F_t *f, struct H5O_layout_t *layout,
-                 H5P_genplist_t *dc_plist, size_t elmt_size,
-		 const H5S_t *space, H5S_sel_iter_t *iter,
-		 hsize_t nelmts, hid_t dxpl_id, const void *_buf)
+    H5P_genplist_t *dc_plist, const H5O_efl_t *efl, size_t elmt_size,
+    const H5S_t *space, H5S_sel_iter_t *iter, hsize_t nelmts,
+    hid_t dxpl_id, const void *_buf)
 {
     const uint8_t *buf=_buf;       /* Alias for pointer arithmetic */
     hsize_t *off=NULL;             /* Array to store sequence offsets */
     size_t *len=NULL;              /* Array to store sequence lengths */
-    size_t vector_size;            /* Value for vector size */
+    ssize_t vector_size;           /* Value for vector size */
     size_t maxbytes;               /* Number of bytes in the buffer */
     size_t  nseq;                  /* Number of sequences generated */
     size_t  nbytes;                /* Number of bytes used in sequences */
-    H5P_genplist_t *dx_plist;      /* Dataset transfer property list */
     herr_t  ret_value=SUCCEED;     /* Return value */
 
     FUNC_ENTER_NOAPI(H5S_select_fscat, FAIL);
@@ -799,6 +827,7 @@ H5S_select_fscat (H5F_t *f, struct H5O_layout_t *layout,
     assert (f);
     assert (layout);
     assert (elmt_size>0);
+    assert (efl);
     assert (space);
     assert (iter);
     assert (nelmts>0);
@@ -806,15 +835,13 @@ H5S_select_fscat (H5F_t *f, struct H5O_layout_t *layout,
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
 
     /* Get the hyperslab vector size */
-    if(NULL == (dx_plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file access property list");
-    if (H5P_get(dx_plist,H5D_XFER_HYPER_VECTOR_SIZE_NAME,&vector_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get value");
+    if((vector_size=H5S_get_vector_size(dxpl_id))<0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get I/O vector size");
 
     /* Allocate the vector I/O arrays */
-    if((len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O length vector array");
-    if((off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O offset vector array");
 
     /* Compute the number of bytes available in buffer */
@@ -823,11 +850,11 @@ H5S_select_fscat (H5F_t *f, struct H5O_layout_t *layout,
     /* Loop until all elements are written */
     while(maxbytes>0) {
         /* Get list of sequences for selection to write */
-        if((*space->select.get_seq_list)(space,H5S_GET_SEQ_LIST_SORTED,iter,elmt_size,vector_size,maxbytes,&nseq,&nbytes,off,len)<0)
+        if((*space->select.get_seq_list)(space,H5S_GET_SEQ_LIST_SORTED,iter,elmt_size,(size_t)vector_size,maxbytes,&nseq,&nbytes,off,len)<0)
             HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, FAIL, "sequence length generation failed");
 
         /* Write sequence list out */
-        if (H5F_seq_writev(f, dxpl_id, layout, dc_plist, space, elmt_size, nseq, len, off, buf)<0)
+        if (H5F_seq_writev(f, dxpl_id, layout, dc_plist, efl, space, elmt_size, nseq, len, off, buf)<0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_WRITEERROR, FAIL, "write error");
 
         /* Update buffer */
@@ -872,19 +899,17 @@ done:
  */
 hsize_t
 H5S_select_fgath (H5F_t *f, const struct H5O_layout_t *layout,
-               H5P_genplist_t *dc_plist,
-	       size_t elmt_size, const H5S_t *space,
-	       H5S_sel_iter_t *iter, hsize_t nelmts, hid_t dxpl_id,
-	       void *_buf/*out*/)
+    H5P_genplist_t *dc_plist, const H5O_efl_t *efl, size_t elmt_size,
+    const H5S_t *space, H5S_sel_iter_t *iter, hsize_t nelmts,
+    hid_t dxpl_id, void *_buf/*out*/)
 {
     uint8_t *buf=_buf;          /* Alias for pointer arithmetic */
     hsize_t *off=NULL;          /* Array to store sequence offsets */
     size_t *len=NULL;           /* Array to store sequence lengths */
-    size_t vector_size;         /* Value for vector size */
+    ssize_t vector_size;        /* Value for vector size */
     size_t maxbytes;            /* Number of bytes in the buffer */
     size_t nseq;                /* Number of sequences generated */
     size_t nbytes;              /* Number of bytes used in sequences */
-    H5P_genplist_t *dx_plist;   /* Dataset transfer property list */
     hsize_t ret_value=nelmts;   /* Return value */
 
     FUNC_ENTER_NOAPI(H5S_select_fgath, 0);
@@ -893,21 +918,20 @@ H5S_select_fgath (H5F_t *f, const struct H5O_layout_t *layout,
     assert (f);
     assert (layout);
     assert (elmt_size>0);
+    assert (efl);
     assert (space);
     assert (iter);
     assert (nelmts>0);
     assert (_buf);
 
     /* Get the hyperslab vector size */
-    if(NULL == (dx_plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "not a file access property list");
-    if (H5P_get(dx_plist,H5D_XFER_HYPER_VECTOR_SIZE_NAME,&vector_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, 0, "unable to get value");
+    if((vector_size=H5S_get_vector_size(dxpl_id))<0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, 0, "unable to get I/O vector size");
 
     /* Allocate the vector I/O arrays */
-    if((len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, 0, "can't allocate I/O length vector array");
-    if((off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, 0, "can't allocate I/O offset vector array");
 
     /* Compute the number of bytes available in buffer */
@@ -916,11 +940,11 @@ H5S_select_fgath (H5F_t *f, const struct H5O_layout_t *layout,
     /* Loop until all elements are written */
     while(maxbytes>0) {
         /* Get list of sequences for selection to write */
-        if((*space->select.get_seq_list)(space,H5S_GET_SEQ_LIST_SORTED,iter,elmt_size,vector_size,maxbytes,&nseq,&nbytes,off,len)<0)
+        if((*space->select.get_seq_list)(space,H5S_GET_SEQ_LIST_SORTED,iter,elmt_size,(size_t)vector_size,maxbytes,&nseq,&nbytes,off,len)<0)
             HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, 0, "sequence length generation failed");
 
         /* Read sequence list in */
-        if (H5F_seq_readv(f, dxpl_id, layout, dc_plist, space, elmt_size, nseq, len, off, buf)<0)
+        if (H5F_seq_readv(f, dxpl_id, layout, dc_plist, efl, space, elmt_size, nseq, len, off, buf)<0)
             HGOTO_ERROR(H5E_DATASPACE, H5E_READERROR, 0, "read error");
 
         /* Update buffer */
@@ -961,11 +985,10 @@ herr_t
 H5S_select_mscat (const void *_tscat_buf, size_t elmt_size, const H5S_t *space,
     H5S_sel_iter_t *iter, hsize_t nelmts, hid_t dxpl_id, void *_buf/*out*/)
 {
-    H5P_genplist_t *dx_plist;   /* Dataset transfer property list */
     uint8_t *buf=(uint8_t *)_buf;   /* Get local copies for address arithmetic */
     const uint8_t *tscat_buf=(const uint8_t *)_tscat_buf;
     hsize_t *off=NULL;          /* Array to store sequence offsets */
-    size_t vector_size;         /* Value for vector size */
+    ssize_t vector_size;        /* Value for vector size */
     size_t *len=NULL;           /* Array to store sequence lengths */
     size_t curr_len;            /* Length of bytes left to process in sequence */
     size_t maxbytes;            /* Number of bytes in the buffer */
@@ -985,15 +1008,13 @@ H5S_select_mscat (const void *_tscat_buf, size_t elmt_size, const H5S_t *space,
     assert (buf);
 
     /* Get the hyperslab vector size */
-    if(NULL == (dx_plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list");
-    if (H5P_get(dx_plist,H5D_XFER_HYPER_VECTOR_SIZE_NAME,&vector_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get value");
+    if((vector_size=H5S_get_vector_size(dxpl_id))<0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get I/O vector size");
 
     /* Allocate the vector I/O arrays */
-    if((len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O length vector array");
-    if((off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O offset vector array");
 
     /* Compute the number of bytes available in buffer */
@@ -1002,7 +1023,7 @@ H5S_select_mscat (const void *_tscat_buf, size_t elmt_size, const H5S_t *space,
     /* Loop until all elements are written */
     while(maxbytes>0) {
         /* Get list of sequences for selection to write */
-        if((*space->select.get_seq_list)(space,0,iter,elmt_size,vector_size,maxbytes,&nseq,&nbytes,off,len)<0)
+        if((*space->select.get_seq_list)(space,0,iter,elmt_size,(size_t)vector_size,maxbytes,&nseq,&nbytes,off,len)<0)
             HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, 0, "sequence length generation failed");
 
         /* Loop, while sequences left to process */
@@ -1053,11 +1074,10 @@ hsize_t
 H5S_select_mgath (const void *_buf, size_t elmt_size, const H5S_t *space,
     H5S_sel_iter_t *iter, hsize_t nelmts, hid_t dxpl_id, void *_tgath_buf/*out*/)
 {
-    H5P_genplist_t *dx_plist;   /* Dataset transfer property list */
     const uint8_t *buf=(const uint8_t *)_buf;   /* Get local copies for address arithmetic */
     uint8_t *tgath_buf=(uint8_t *)_tgath_buf;
     hsize_t *off=NULL;          /* Array to store sequence offsets */
-    size_t vector_size;         /* Value for vector size */
+    ssize_t vector_size;        /* Value for vector size */
     size_t *len=NULL;           /* Array to store sequence lengths */
     size_t curr_len;            /* Length of bytes left to process in sequence */
     size_t maxbytes;            /* Number of bytes in the buffer */
@@ -1077,15 +1097,13 @@ H5S_select_mgath (const void *_buf, size_t elmt_size, const H5S_t *space,
     assert (tgath_buf);
 
     /* Get the hyperslab vector size */
-    if(NULL == (dx_plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, 0, "not a dataset transfer property list");
-    if (H5P_get(dx_plist,H5D_XFER_HYPER_VECTOR_SIZE_NAME,&vector_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, 0, "unable to get value");
+    if((vector_size=H5S_get_vector_size(dxpl_id))<0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, 0, "unable to get I/O vector size");
 
     /* Allocate the vector I/O arrays */
-    if((len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, 0, "can't allocate I/O length vector array");
-    if((off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, 0, "can't allocate I/O offset vector array");
 
     /* Compute the number of bytes available in buffer */
@@ -1094,7 +1112,7 @@ H5S_select_mgath (const void *_buf, size_t elmt_size, const H5S_t *space,
     /* Loop until all elements are written */
     while(maxbytes>0) {
         /* Get list of sequences for selection to write */
-        if((*space->select.get_seq_list)(space,0,iter,elmt_size,vector_size,maxbytes,&nseq,&nbytes,off,len)<0)
+        if((*space->select.get_seq_list)(space,0,iter,elmt_size,(size_t)vector_size,maxbytes,&nseq,&nbytes,off,len)<0)
             HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, 0, "sequence length generation failed");
 
         /* Loop, while sequences left to process */
@@ -1138,16 +1156,17 @@ done:
  */
 herr_t
 H5S_select_read(H5F_t *f, const H5O_layout_t *layout, H5P_genplist_t *dc_plist,
-            size_t elmt_size, const H5S_t *file_space,
-	    const H5S_t *mem_space, hid_t dxpl_id, void *_buf/*out*/)
+    const H5O_efl_t *efl, size_t elmt_size, const H5S_t *file_space,
+    const H5S_t *mem_space, hid_t dxpl_id, void *_buf/*out*/)
 {
-    H5P_genplist_t *dx_plist;   /* Dataset transfer property list */
-    H5S_sel_iter_t *mem_iter=NULL;   /* Memory selection iteration info */
-    H5S_sel_iter_t *file_iter=NULL;  /* File selection iteration info */
+    H5S_sel_iter_t mem_iter;    /* Memory selection iteration info */
+    hbool_t mem_iter_init=0;    /* Memory selection iteration info has been initialized */
+    H5S_sel_iter_t file_iter;   /* File selection iteration info */
+    hbool_t file_iter_init=0;	/* File selection iteration info has been initialized */
     uint8_t *buf=NULL;          /* Local buffer pointer, for address arithmetic */
     hsize_t *mem_off=NULL;      /* Array to store sequence offsets in memory */
     hsize_t *file_off=NULL;     /* Array to store sequence offsets in the file */
-    size_t vector_size;         /* Value for vector size */
+    ssize_t vector_size;        /* Value for vector size */
     size_t *mem_len=NULL;       /* Array to store sequence lengths in memory */
     size_t *file_len=NULL;      /* Array to store sequence lengths in the file */
     size_t maxbytes;            /* Number of bytes in selection */
@@ -1168,40 +1187,33 @@ H5S_select_read(H5F_t *f, const H5O_layout_t *layout, H5P_genplist_t *dc_plist,
 
     /* Check args */
     assert(f);
+    assert(efl);
     assert(_buf);
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
 
     /* Get the hyperslab vector size */
-    if(NULL == (dx_plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list");
-    if (H5P_get(dx_plist,H5D_XFER_HYPER_VECTOR_SIZE_NAME,&vector_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get value");
+    if((vector_size=H5S_get_vector_size(dxpl_id))<0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get I/O vector size");
 
     /* Allocate the vector I/O arrays */
-    if((mem_len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((mem_len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O length vector array");
-    if((mem_off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((mem_off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O offset vector array");
-    if((file_len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((file_len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O length vector array");
-    if((file_off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((file_off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O offset vector array");
 
-    /* Allocate file iterator */
-    if((file_iter = H5FL_ALLOC(H5S_sel_iter_t,1))==NULL)
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate selection iterator");
-
     /* Initialize file iterator */
-    if ((*file_space->select.iter_init)(file_space, elmt_size, file_iter)<0)
+    if ((*file_space->select.iter_init)(file_space, elmt_size, &file_iter)<0)
         HGOTO_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to initialize selection iterator");
-
-    /* Allocate memory iterator */
-    if((mem_iter = H5FL_ALLOC(H5S_sel_iter_t,1))==NULL)
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate selection iterator");
+    file_iter_init=1;	/* File selection iteration info has been initialized */
 
     /* Initialize memory iterator */
-    if ((*mem_space->select.iter_init)(mem_space, elmt_size, mem_iter)<0)
+    if ((*mem_space->select.iter_init)(mem_space, elmt_size, &mem_iter)<0)
         HGOTO_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to initialize selection iterator");
+    mem_iter_init=1;	/* Memory selection iteration info has been initialized */
 
     /* Get number of bytes in selection */
     maxbytes=(*file_space->select.get_npoints)(file_space)*elmt_size;
@@ -1215,7 +1227,7 @@ H5S_select_read(H5F_t *f, const H5O_layout_t *layout, H5P_genplist_t *dc_plist,
         /* Check if more file sequences are needed */
         if(curr_file_seq>=file_nseq) {
             /* Get sequences for file selection */
-            if((*file_space->select.get_seq_list)(file_space,H5S_GET_SEQ_LIST_SORTED,file_iter,elmt_size,vector_size,maxbytes,&file_nseq,&file_nbytes,file_off,file_len)<0)
+            if((*file_space->select.get_seq_list)(file_space,H5S_GET_SEQ_LIST_SORTED,&file_iter,elmt_size,(size_t)vector_size,maxbytes,&file_nseq,&file_nbytes,file_off,file_len)<0)
                 HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, FAIL, "sequence length generation failed");
 
             /* Start at the beginning of the sequences again */
@@ -1225,7 +1237,7 @@ H5S_select_read(H5F_t *f, const H5O_layout_t *layout, H5P_genplist_t *dc_plist,
         /* Check if more memory sequences are needed */
         if(curr_mem_seq>=mem_nseq) {
             /* Get sequences for memory selection */
-            if((*mem_space->select.get_seq_list)(mem_space,0,mem_iter,elmt_size,vector_size,maxbytes,&mem_nseq,&mem_nbytes,mem_off,mem_len)<0)
+            if((*mem_space->select.get_seq_list)(mem_space,0,&mem_iter,elmt_size,(size_t)vector_size,maxbytes,&mem_nseq,&mem_nbytes,mem_off,mem_len)<0)
                 HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, FAIL, "sequence length generation failed");
 
             /* Start at the beginning of the sequences again */
@@ -1271,7 +1283,7 @@ H5S_select_read(H5F_t *f, const H5O_layout_t *layout, H5P_genplist_t *dc_plist,
                 partial_file=0;
 
             /* Read file sequences into current memory sequence */
-            if (H5F_seq_readv(f, dxpl_id, layout, dc_plist, file_space, elmt_size, tot_file_seq, &file_len[orig_file_seq], &file_off[orig_file_seq], buf)<0)
+            if (H5F_seq_readv(f, dxpl_id, layout, dc_plist, efl, file_space, elmt_size, tot_file_seq, &file_len[orig_file_seq], &file_off[orig_file_seq], buf)<0)
                 HGOTO_ERROR(H5E_DATASPACE, H5E_READERROR, FAIL, "read error");
 
             /* Update last file sequence, if it was partially accessed */
@@ -1308,7 +1320,7 @@ H5S_select_read(H5F_t *f, const H5O_layout_t *layout, H5P_genplist_t *dc_plist,
             tmp_file_len=mem_len[curr_mem_seq];
 
             /* Read part of current file sequence into current memory sequence */
-            if (H5F_seq_read(f, dxpl_id, layout, dc_plist, file_space, elmt_size, tmp_file_len, file_off[curr_file_seq], buf)<0)
+            if (H5F_seq_read(f, dxpl_id, layout, dc_plist, efl, file_space, elmt_size, tmp_file_len, file_off[curr_file_seq], buf)<0)
                 HGOTO_ERROR(H5E_DATASPACE, H5E_READERROR, FAIL, "read error");
 
             /* Update current file sequence information */
@@ -1331,17 +1343,15 @@ H5S_select_read(H5F_t *f, const H5O_layout_t *layout, H5P_genplist_t *dc_plist,
 
 done:
     /* Release file selection iterator */
-    if(file_iter!=NULL) {
-        if ((*file_space->select.iter_release)(file_iter)<0)
-            HGOTO_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
-	H5FL_FREE(H5S_sel_iter_t,file_iter);
+    if(file_iter_init) {
+        if ((*file_space->select.iter_release)(&file_iter)<0)
+            HDONE_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
     } /* end if */
 
     /* Release memory selection iterator */
-    if(mem_iter!=NULL) {
-        if ((*mem_space->select.iter_release)(mem_iter)<0)
-            HGOTO_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
-	H5FL_FREE(H5S_sel_iter_t,mem_iter);
+    if(mem_iter_init) {
+        if ((*mem_space->select.iter_release)(&mem_iter)<0)
+            HDONE_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
     } /* end if */
 
     /* Free vector arrays */
@@ -1373,16 +1383,17 @@ done:
  */
 herr_t
 H5S_select_write(H5F_t *f, H5O_layout_t *layout, H5P_genplist_t *dc_plist,
-            size_t elmt_size, const H5S_t *file_space,
-	    const H5S_t *mem_space, hid_t dxpl_id, const void *_buf/*out*/)
+    const H5O_efl_t *efl, size_t elmt_size, const H5S_t *file_space,
+    const H5S_t *mem_space, hid_t dxpl_id, const void *_buf/*out*/)
 {
-    H5P_genplist_t *dx_plist;   /* Dataset transfer property list */
-    H5S_sel_iter_t *mem_iter=NULL;   /* Memory selection iteration info */
-    H5S_sel_iter_t *file_iter=NULL;  /* File selection iteration info */
+    H5S_sel_iter_t mem_iter;    /* Memory selection iteration info */
+    hbool_t mem_iter_init=0;    /* Memory selection iteration info has been initialized */
+    H5S_sel_iter_t file_iter;   /* File selection iteration info */
+    hbool_t file_iter_init=0;	/* File selection iteration info has been initialized */
     const uint8_t *buf=NULL;    /* Local buffer pointer, for address arithmetic */
     hsize_t *mem_off=NULL;      /* Array to store sequence offsets in memory */
     hsize_t *file_off=NULL;     /* Array to store sequence offsets in the file */
-    size_t vector_size;         /* Value for vector size */
+    ssize_t vector_size;        /* Value for vector size */
     size_t *mem_len=NULL;       /* Array to store sequence lengths in memory */
     size_t *file_len=NULL;      /* Array to store sequence lengths in the file */
     size_t maxbytes;            /* Number of bytes in selection */
@@ -1403,40 +1414,33 @@ H5S_select_write(H5F_t *f, H5O_layout_t *layout, H5P_genplist_t *dc_plist,
 
     /* Check args */
     assert(f);
+    assert(efl);
     assert(_buf);
     assert(TRUE==H5P_isa_class(dxpl_id,H5P_DATASET_XFER));
 
     /* Get the hyperslab vector size */
-    if(NULL == (dx_plist = H5P_object_verify(dxpl_id,H5P_DATASET_XFER)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list");
-    if (H5P_get(dx_plist,H5D_XFER_HYPER_VECTOR_SIZE_NAME,&vector_size)<0)
-        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get value");
+    if((vector_size=H5S_get_vector_size(dxpl_id))<0)
+        HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "unable to get I/O vector size");
 
     /* Allocate the vector I/O arrays */
-    if((mem_len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((mem_len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O length vector array");
-    if((mem_off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((mem_off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O offset vector array");
-    if((file_len = H5FL_ARR_ALLOC(size_t,vector_size,0))==NULL)
+    if((file_len = H5FL_ARR_MALLOC(size_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O length vector array");
-    if((file_off = H5FL_ARR_ALLOC(hsize_t,vector_size,0))==NULL)
+    if((file_off = H5FL_ARR_MALLOC(hsize_t,(size_t)vector_size))==NULL)
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate I/O offset vector array");
 
-    /* Allocate file iterator */
-    if((file_iter = H5FL_ALLOC(H5S_sel_iter_t,1))==NULL)
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate selection iterator");
-
     /* Initialize file iterator */
-    if ((*file_space->select.iter_init)(file_space, elmt_size, file_iter)<0)
+    if ((*file_space->select.iter_init)(file_space, elmt_size, &file_iter)<0)
         HGOTO_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to initialize selection iterator");
-
-    /* Allocate memory iterator */
-    if((mem_iter = H5FL_ALLOC(H5S_sel_iter_t,1))==NULL)
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "can't allocate selection iterator");
+    file_iter_init=1;	/* File selection iteration info has been initialized */
 
     /* Initialize memory iterator */
-    if ((*mem_space->select.iter_init)(mem_space, elmt_size, mem_iter)<0)
+    if ((*mem_space->select.iter_init)(mem_space, elmt_size, &mem_iter)<0)
         HGOTO_ERROR (H5E_DATASPACE, H5E_CANTINIT, FAIL, "unable to initialize selection iterator");
+    mem_iter_init=1;	/* Memory selection iteration info has been initialized */
 
     /* Get number of bytes in selection */
     maxbytes=(*file_space->select.get_npoints)(file_space)*elmt_size;
@@ -1450,7 +1454,7 @@ H5S_select_write(H5F_t *f, H5O_layout_t *layout, H5P_genplist_t *dc_plist,
         /* Check if more file sequences are needed */
         if(curr_file_seq>=file_nseq) {
             /* Get sequences for file selection */
-            if((*file_space->select.get_seq_list)(file_space,H5S_GET_SEQ_LIST_SORTED,file_iter,elmt_size,vector_size,maxbytes,&file_nseq,&file_nbytes,file_off,file_len)<0)
+            if((*file_space->select.get_seq_list)(file_space,H5S_GET_SEQ_LIST_SORTED,&file_iter,elmt_size,(size_t)vector_size,maxbytes,&file_nseq,&file_nbytes,file_off,file_len)<0)
                 HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, FAIL, "sequence length generation failed");
 
             /* Start at the beginning of the sequences again */
@@ -1460,7 +1464,7 @@ H5S_select_write(H5F_t *f, H5O_layout_t *layout, H5P_genplist_t *dc_plist,
         /* Check if more memory sequences are needed */
         if(curr_mem_seq>=mem_nseq) {
             /* Get sequences for memory selection */
-            if((*mem_space->select.get_seq_list)(mem_space,0,mem_iter,elmt_size,vector_size,maxbytes,&mem_nseq,&mem_nbytes,mem_off,mem_len)<0)
+            if((*mem_space->select.get_seq_list)(mem_space,0,&mem_iter,elmt_size,(size_t)vector_size,maxbytes,&mem_nseq,&mem_nbytes,mem_off,mem_len)<0)
                 HGOTO_ERROR (H5E_INTERNAL, H5E_UNSUPPORTED, FAIL, "sequence length generation failed");
 
             /* Start at the beginning of the sequences again */
@@ -1506,7 +1510,7 @@ H5S_select_write(H5F_t *f, H5O_layout_t *layout, H5P_genplist_t *dc_plist,
                 partial_file=0;
 
             /* Write current memory sequence into file sequences */
-            if (H5F_seq_writev(f, dxpl_id, layout, dc_plist, file_space, elmt_size, tot_file_seq, &file_len[orig_file_seq], &file_off[orig_file_seq], buf)<0)
+            if (H5F_seq_writev(f, dxpl_id, layout, dc_plist, efl, file_space, elmt_size, tot_file_seq, &file_len[orig_file_seq], &file_off[orig_file_seq], buf)<0)
                 HGOTO_ERROR(H5E_DATASPACE, H5E_WRITEERROR, FAIL, "write error");
 
             /* Update last file sequence, if it was partially accessed */
@@ -1543,7 +1547,7 @@ H5S_select_write(H5F_t *f, H5O_layout_t *layout, H5P_genplist_t *dc_plist,
             tmp_file_len=mem_len[curr_mem_seq];
 
             /* Write part of current memory sequence to current file sequence */
-            if (H5F_seq_write(f, dxpl_id, layout, dc_plist, file_space, elmt_size, tmp_file_len, file_off[curr_file_seq], buf)<0)
+            if (H5F_seq_write(f, dxpl_id, layout, dc_plist, efl, file_space, elmt_size, tmp_file_len, file_off[curr_file_seq], buf)<0)
                 HGOTO_ERROR(H5E_DATASPACE, H5E_WRITEERROR, FAIL, "write error");
 
             /* Update current file sequence information */
@@ -1566,17 +1570,15 @@ H5S_select_write(H5F_t *f, H5O_layout_t *layout, H5P_genplist_t *dc_plist,
 
 done:
     /* Release file selection iterator */
-    if(file_iter!=NULL) {
-        if ((*file_space->select.iter_release)(file_iter)<0)
-            HGOTO_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
-	H5FL_FREE(H5S_sel_iter_t,file_iter);
+    if(file_iter_init) {
+        if ((*file_space->select.iter_release)(&file_iter)<0)
+            HDONE_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
     } /* end if */
 
     /* Release memory selection iterator */
-    if(mem_iter!=NULL) {
-        if ((*mem_space->select.iter_release)(mem_iter)<0)
-            HGOTO_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
-	H5FL_FREE(H5S_sel_iter_t,mem_iter);
+    if(mem_iter_init) {
+        if ((*mem_space->select.iter_release)(&mem_iter)<0)
+            HDONE_ERROR (H5E_DATASPACE, H5E_CANTRELEASE, FAIL, "unable to release selection iterator");
     } /* end if */
 
     /* Free vector arrays */
diff --git a/src/H5T.c b/src/H5T.c
index 51b14d5..64cc2e3 100644
--- a/src/H5T.c
+++ b/src/H5T.c
@@ -1522,7 +1522,7 @@ H5T_init_interface(void)
 
     /* Opaque data */
     if(H5T_NATIVE_OPAQUE_g<0) {
-        if (NULL==(dt = H5FL_ALLOC(H5T_t,1)))
+        if (NULL==(dt = H5FL_CALLOC(H5T_t)))
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
         /* Set information */
@@ -1544,7 +1544,7 @@ H5T_init_interface(void)
 
     /* One-byte character string */
     if(H5T_C_S1_g<0) {
-        if (NULL==(dt = H5FL_ALLOC(H5T_t,1)))
+        if (NULL==(dt = H5FL_CALLOC(H5T_t)))
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
         dt->state = H5T_STATE_IMMUTABLE;
@@ -1570,7 +1570,7 @@ H5T_init_interface(void)
 
     /* One-byte character string */
     if(H5T_FORTRAN_S1_g<0) {
-        if (NULL==(dt = H5FL_ALLOC(H5T_t,1)))
+        if (NULL==(dt = H5FL_CALLOC(H5T_t)))
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
         dt->state = H5T_STATE_IMMUTABLE;
@@ -1596,7 +1596,7 @@ H5T_init_interface(void)
 
     /* Object pointer (i.e. object header address in file) */
     if(H5T_STD_REF_OBJ_g<0) {
-        if (NULL==(dt = H5FL_ALLOC(H5T_t,1)))
+        if (NULL==(dt = H5FL_CALLOC(H5T_t)))
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
         dt->state = H5T_STATE_IMMUTABLE;
@@ -1616,7 +1616,7 @@ H5T_init_interface(void)
     
     /* Dataset Region pointer (i.e. selection inside a dataset) */
     if(H5T_STD_REF_DSETREG_g<0) {
-        if (NULL==(dt = H5FL_ALLOC(H5T_t,1)))
+        if (NULL==(dt = H5FL_CALLOC(H5T_t)))
             HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
 
         dt->state = H5T_STATE_IMMUTABLE;
@@ -1897,7 +1897,7 @@ H5T_term_interface(void)
 		H5T_print_stats(path, &nprint/*in,out*/);
 		path->cdata.command = H5T_CONV_FREE;
 		if ((path->func)(FAIL, FAIL, &(path->cdata),
-				 (hsize_t)0, 0, 0, NULL, NULL,H5P_DEFAULT)<0) {
+				 (hsize_t)0, 0, 0, NULL, NULL,H5P_DATASET_XFER_DEFAULT)<0) {
 #ifdef H5T_DEBUG
 		    if (H5DEBUG(T)) {
 			fprintf (H5DEBUG(T), "H5T: conversion function "
@@ -2688,7 +2688,7 @@ hid_t H5Tget_native_type(hid_t type_id, H5T_direction_t direction)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
     if(direction!=H5T_DIR_DEFAULT && direction!=H5T_DIR_ASCEND 
-        && direction!=H5T_DIR_DESCEND)
+            && direction!=H5T_DIR_DESCEND)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not valid direction value");
 
     if((new_dt = H5T_get_native_type(dt, direction, NULL, NULL, &comp_size))==NULL)
@@ -2732,7 +2732,7 @@ H5T_t* H5T_get_native_type(H5T_t *dtype, H5T_direction_t direction, size_t *stru
     int         nmemb;              /* Number of members in compound & enum types */
     H5T_t       *super_type;        /* Super type of VL, array and enum datatypes */
     H5T_t       *nat_super_type;    /* Native form of VL, array & enum super datatype */
-    H5T_t       *new_type;          /* New native datatype */
+    H5T_t       *new_type=NULL;     /* New native datatype */
     int         i;                  /* Local index variable */
     H5T_t       *ret_value;         /* Return value */
 
@@ -2771,7 +2771,7 @@ H5T_t* H5T_get_native_type(H5T_t *dtype, H5T_direction_t direction, size_t *stru
                 size_t pointer_size;
 
                 if(H5T_is_variable_str(dtype)) {
-                    if(NULL==(dt=H5I_object_verify(H5T_C_S1, H5I_DATATYPE)))
+                    if(NULL==(dt=H5I_object(H5T_C_S1)))
                         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a data type");
                     if((ret_value=H5T_copy(dt, H5T_COPY_TRANSIENT))==NULL)
                         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "cannot retrieve float type");
@@ -2788,7 +2788,7 @@ H5T_t* H5T_get_native_type(H5T_t *dtype, H5T_direction_t direction, size_t *stru
                 } else { 
                     /*size_t          char_size;*/
 
-                    if(NULL==(dt=H5I_object_verify(H5T_NATIVE_UCHAR, H5I_DATATYPE)))
+                    if(NULL==(dt=H5I_object(H5T_NATIVE_UCHAR)))
                         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a data type");
                     if((ret_value=H5T_copy(dt, H5T_COPY_TRANSIENT))==NULL)
                         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "cannot retrieve float type");
@@ -2801,8 +2801,6 @@ H5T_t* H5T_get_native_type(H5T_t *dtype, H5T_direction_t direction, size_t *stru
                     if(H5T_cmp_offset(comp_size, offset, sizeof(char), size, align, struct_align)<0)
                         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "cannot compute compound offset");
 
-                    if(H5T_close(dt)<0)
-                        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "can't close data type");
                 }
             }
             break;
@@ -2821,13 +2819,12 @@ H5T_t* H5T_get_native_type(H5T_t *dtype, H5T_direction_t direction, size_t *stru
                 size_t align;
                 size_t ref_size;
                 int    not_equal;
-                H5T_t  *dt;
 
                 if((ret_value=H5T_copy(dtype, H5T_COPY_TRANSIENT))==NULL)
                     HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "cannot retrieve float type");
                
                 /* Decide if the data type is object or dataset region reference. */
-                if(NULL==(dt=H5I_object_verify(H5T_STD_REF_OBJ_g, H5I_DATATYPE)))
+                if(NULL==(dt=H5I_object(H5T_STD_REF_OBJ_g)))
                     HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a data type");
                 not_equal = H5T_cmp(ret_value, dt);
 
@@ -2975,7 +2972,6 @@ H5T_t* H5T_get_native_type(H5T_t *dtype, H5T_direction_t direction, size_t *stru
                 size_t      super_offset=0;       
                 size_t      super_size=0;       
                 size_t      super_align=0;   
-                int         i;
 
                 /* Retrieve dimension information for array data type */
                 if((array_rank=H5T_get_array_ndims(dtype))<=0)
@@ -3006,7 +3002,8 @@ H5T_t* H5T_get_native_type(H5T_t *dtype, H5T_direction_t direction, size_t *stru
                     
                 for(i=0; i<array_rank; i++)
                     nelems *= dims[i];                   
-                if(H5T_cmp_offset(comp_size, offset, super_size, nelems, super_align, struct_align)<0)
+                H5_CHECK_OVERFLOW(nelems,hsize_t,size_t);
+                if(H5T_cmp_offset(comp_size, offset, super_size, (size_t)nelems, super_align, struct_align)<0)
                     HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "cannot compute compound offset");
                         
                 H5MM_xfree(dims);
@@ -3086,8 +3083,8 @@ H5T_t* H5T_get_native_integer(size_t size, H5T_sign_t sign, H5T_direction_t dire
                               size_t *struct_align, size_t *offset, size_t *comp_size)
 {  
     H5T_t       *dt;            /* Appropriate native datatype to copy */
-    hid_t       tid;            /* Datatype ID of appropriate native datatype */
-    size_t      align;          /* Alignment necessary for native datatype */
+    hid_t       tid=(-1);       /* Datatype ID of appropriate native datatype */
+    size_t      align=0;        /* Alignment necessary for native datatype */
     enum match_type {           /* The different kinds of integers we can match */
         H5T_NATIVE_INT_MATCH_CHAR,
         H5T_NATIVE_INT_MATCH_SHORT,
@@ -3183,7 +3180,8 @@ H5T_t* H5T_get_native_integer(size_t size, H5T_sign_t sign, H5T_direction_t dire
     } /* end switch */
         
     /* Create new native type */
-    if(NULL==(dt=H5I_object_verify(tid, H5I_DATATYPE)))
+    assert(tid>=0);
+    if(NULL==(dt=H5I_object(tid)))
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a data type");
     if((ret_value=H5T_copy(dt, H5T_COPY_TRANSIENT))==NULL)
          HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "cannot retrieve float type");
@@ -3216,8 +3214,8 @@ done:
 H5T_t* H5T_get_native_float(size_t size, H5T_direction_t direction, size_t *struct_align, size_t *offset, size_t *comp_size)
 {  
     H5T_t       *dt=NULL;       /* Appropriate native datatype to copy */
-    hid_t       tid;            /* Datatype ID of appropriate native datatype */
-    size_t      align;          /* Alignment necessary for native datatype */
+    hid_t       tid=(-1);       /* Datatype ID of appropriate native datatype */
+    size_t      align=0;        /* Alignment necessary for native datatype */
     enum match_type {           /* The different kinds of floating point types we can match */
         H5T_NATIVE_FLOAT_MATCH_FLOAT,
         H5T_NATIVE_FLOAT_MATCH_DOUBLE,
@@ -3273,7 +3271,8 @@ H5T_t* H5T_get_native_float(size_t size, H5T_direction_t direction, size_t *stru
     } /* end switch */
    
     /* Create new native type */
-    if(NULL==(dt=H5I_object_verify(tid, H5I_DATATYPE)))
+    assert(tid>=0);
+    if(NULL==(dt=H5I_object(tid)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "not a data type");
     if((ret_value=H5T_copy(dt, H5T_COPY_TRANSIENT))==NULL)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, NULL, "cannot retrieve float type");
@@ -5201,7 +5200,7 @@ H5T_enum_create(H5T_t *parent)
     assert(parent);
 
     /* Build new type */
-    if (NULL==(ret_value = H5FL_ALLOC(H5T_t,1)))
+    if (NULL==(ret_value = H5FL_CALLOC(H5T_t)))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     ret_value->type = H5T_ENUM;
     ret_value->parent = H5T_copy(parent, H5T_COPY_ALL);
@@ -5546,7 +5545,7 @@ H5T_vlen_create(H5T_t *base)
     assert(base);
 
     /* Build new type */
-    if (NULL==(dt = H5FL_ALLOC(H5T_t,1)))
+    if (NULL==(dt = H5FL_CALLOC(H5T_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     dt->ent.header = HADDR_UNDEF;
     dt->type = H5T_VLEN;
@@ -5797,7 +5796,7 @@ H5T_register(H5T_pers_t pers, const char *name, H5T_t *src, H5T_t *dst,
                 HGOTO_ERROR(H5E_DATATYPE, H5E_CANTREGISTER, FAIL, "unable to register data types for conv query");
             HDmemset(&cdata, 0, sizeof cdata);
             cdata.command = H5T_CONV_INIT;
-            if ((func)(tmp_sid, tmp_did, &cdata, (hsize_t)0, 0, 0, NULL, NULL, H5P_DEFAULT)<0) {
+            if ((func)(tmp_sid, tmp_did, &cdata, (hsize_t)0, 0, 0, NULL, NULL, H5P_DATASET_XFER_DEFAULT)<0) {
                 H5I_dec_ref(tmp_sid);
                 H5I_dec_ref(tmp_did);
                 tmp_sid = tmp_did = -1;
@@ -5806,7 +5805,7 @@ H5T_register(H5T_pers_t pers, const char *name, H5T_t *src, H5T_t *dst,
             } /* end if */
 
             /* Create a new conversion path */
-            if (NULL==(new_path=H5FL_ALLOC(H5T_path_t,1)))
+            if (NULL==(new_path=H5FL_CALLOC(H5T_path_t)))
                 HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed");
             HDstrncpy(new_path->name, name, H5T_NAMELEN);
             new_path->name[H5T_NAMELEN-1] = '\0';
@@ -5824,7 +5823,7 @@ H5T_register(H5T_pers_t pers, const char *name, H5T_t *src, H5T_t *dst,
             /* Free old path */
             H5T_print_stats(old_path, &nprint);
             old_path->cdata.command = H5T_CONV_FREE;
-            if ((old_path->func)(tmp_sid, tmp_did, &(old_path->cdata), (hsize_t)0, 0, 0, NULL, NULL, H5P_DEFAULT)<0) {
+            if ((old_path->func)(tmp_sid, tmp_did, &(old_path->cdata), (hsize_t)0, 0, 0, NULL, NULL, H5P_DATASET_XFER_DEFAULT)<0) {
 #ifdef H5T_DEBUG
 		if (H5DEBUG(T)) {
 		    fprintf (H5DEBUG(T), "H5T: conversion function 0x%08lx "
@@ -5986,7 +5985,7 @@ H5T_unregister(H5T_pers_t pers, const char *name, H5T_t *src, H5T_t *dst,
         H5T_print_stats(path, &nprint);
         path->cdata.command = H5T_CONV_FREE;
         if ((path->func)(FAIL, FAIL, &(path->cdata), (hsize_t)0, 0, 0, NULL, NULL,
-                         H5P_DEFAULT)<0) {
+                         H5P_DATASET_XFER_DEFAULT)<0) {
 #ifdef H5T_DEBUG
 	    if (H5DEBUG(T)) {
 		fprintf(H5DEBUG(T), "H5T: conversion function 0x%08lx failed "
@@ -6141,9 +6140,13 @@ H5Tconvert(hid_t src_id, hid_t dst_id, hsize_t nelmts, void *buf,
 
     /* Check args */
     if (NULL==(src=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-            NULL==(dst=H5I_object_verify(dst_id,H5I_DATATYPE)) ||
-            (H5P_DEFAULT!=plist_id && TRUE != H5P_isa_class(plist_id, H5P_DATASET_XFER)))
+            NULL==(dst=H5I_object_verify(dst_id,H5I_DATATYPE)))
 	HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
+    if(H5P_DEFAULT == plist_id)
+        plist_id = H5P_DATASET_XFER_DEFAULT;
+    else
+        if(TRUE != H5P_isa_class(plist_id, H5P_DATASET_XFER))
+            HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not dataset transfer property list");
 
     /* Find the conversion function */
     if (NULL==(tpath=H5T_path_find(src, dst, NULL, NULL)))
@@ -6272,7 +6275,7 @@ H5T_create(H5T_class_t type, size_t size)
 
         case H5T_OPAQUE:
         case H5T_COMPOUND:
-            if (NULL==(dt = H5FL_ALLOC(H5T_t,1)))
+            if (NULL==(dt = H5FL_CALLOC(H5T_t)))
                 HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
             dt->type = type;
             break;
@@ -6291,7 +6294,7 @@ H5T_create(H5T_class_t type, size_t size)
             } else {
                 HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "no applicable native integer type");
             }
-            if (NULL==(dt = H5FL_ALLOC(H5T_t,1)))
+            if (NULL==(dt = H5FL_CALLOC(H5T_t)))
                 HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
             dt->type = type;
             if (NULL==(dt->parent=H5T_copy(H5I_object(subtype), H5T_COPY_ALL)))
@@ -6506,7 +6509,7 @@ H5T_copy(const H5T_t *old_dt, H5T_copy_t method)
     assert(old_dt);
 
     /* Allocate space */
-    if (NULL==(new_dt = H5FL_ALLOC(H5T_t,0)))
+    if (NULL==(new_dt = H5FL_MALLOC(H5T_t)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     /* Copy actual information */
@@ -6725,7 +6728,7 @@ H5T_commit (H5G_entry_t *loc, const char *name, H5T_t *type)
      */
     if (H5O_create (file, 64, &(type->ent))<0)
 	HGOTO_ERROR (H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to create data type object header");
-    if (H5O_modify (&(type->ent), H5O_DTYPE, 0, H5O_FLAG_CONSTANT, type)<0)
+    if (H5O_modify (&(type->ent), H5O_DTYPE, 0, H5O_FLAG_CONSTANT, 1, type)<0)
 	HGOTO_ERROR (H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to update type header message");
     if (H5G_insert (loc, name, &(type->ent))<0)
 	HGOTO_ERROR (H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to name data type");
@@ -6789,36 +6792,27 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5T_close
+ * Function:	H5T_release
  *
- * Purpose:	Frees a data type and all associated memory.  If the data
- *		type is locked then nothing happens.
+ * Purpose:	Frees all memory associated with a datatype, but does not
+ *              free the H5T_t structure (which should be done in H5T_close).
  *
  * Return:	Non-negative on success/Negative on failure
  *
- * Programmer:	Robb Matzke
- *		Monday, December  8, 1997
+ * Programmer:	Quincey Koziol
+ *		Monday, January  6, 2003
  *
  * Modifications:
- *      Robb Matzke, 1999-04-27
- *      This function fails if the datatype state is IMMUTABLE.
- *
- *      Robb Matzke, 1999-05-20
- *      Closes opaque types also.
- *
- *      Pedro Vicente, <pvn@ncsa.uiuc.edu> 22 Aug 2002
- *      Added "ID to name" support
  *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5T_close(H5T_t *dt)
+H5T_free(H5T_t *dt)
 {
     int	i;
-    H5T_t	*parent = dt->parent;
     herr_t      ret_value=SUCCEED;       /* Return value */
 
-    FUNC_ENTER_NOAPI(H5T_close, FAIL);
+    FUNC_ENTER_NOAPI(H5T_free, FAIL);
 
     assert(dt);
 
@@ -6866,15 +6860,58 @@ H5T_close(H5T_t *dt)
     /* Free the ID to name info */
     H5G_free_ent_name(&(dt->ent));
 
-    /* Free the datatype struct */
-    H5FL_FREE(H5T_t,dt);
-
     /* Close the parent */
-    if (parent && H5T_close(parent)<0)
+    if (dt->parent && H5T_close(dt->parent)<0)
 	HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to close parent data type");
     
 done:
     FUNC_LEAVE(ret_value);
+} /* end H5T_free() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5T_close
+ *
+ * Purpose:	Frees a data type and all associated memory.  If the data
+ *		type is locked then nothing happens.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Robb Matzke
+ *		Monday, December  8, 1997
+ *
+ * Modifications:
+ *      Robb Matzke, 1999-04-27
+ *      This function fails if the datatype state is IMMUTABLE.
+ *
+ *      Robb Matzke, 1999-05-20
+ *      Closes opaque types also.
+ *
+ *      Pedro Vicente, <pvn@ncsa.uiuc.edu> 22 Aug 2002
+ *      Added "ID to name" support
+ *
+ *      Quincey Koziol, 2003-01-06
+ *      Moved "guts" of function to H5T_free()
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5T_close(H5T_t *dt)
+{
+    herr_t      ret_value=SUCCEED;       /* Return value */
+
+    FUNC_ENTER_NOAPI(H5T_close, FAIL);
+
+    assert(dt);
+
+    if(H5T_free(dt)<0) 
+        HGOTO_ERROR(H5E_DATATYPE, H5E_CANTFREE, FAIL, "unable to free datatype");
+
+    /* Free the datatype struct */
+    H5FL_FREE(H5T_t,dt);
+
+done:
+    FUNC_LEAVE(ret_value);
 }
 
 
@@ -8267,13 +8304,13 @@ H5T_path_find(const H5T_t *src, const H5T_t *dst, const char *name,
 	if (NULL==(H5T_g.path=H5MM_malloc(128*sizeof(H5T_path_t*))))
 	    HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for type conversion path table");
 	H5T_g.apaths = 128;
-	if (NULL==(H5T_g.path[0]=H5FL_ALLOC(H5T_path_t,1)))
+	if (NULL==(H5T_g.path[0]=H5FL_CALLOC(H5T_path_t)))
 	    HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for no-op conversion path");
 	HDstrcpy(H5T_g.path[0]->name, "no-op");
 	H5T_g.path[0]->func = H5T_conv_noop;
 	H5T_g.path[0]->cdata.command = H5T_CONV_INIT;
 	if (H5T_conv_noop(FAIL, FAIL, &(H5T_g.path[0]->cdata), (hsize_t)0, 0, 0,
-			  NULL, NULL, H5P_DEFAULT)<0) {
+			  NULL, NULL, H5P_DATASET_XFER_DEFAULT)<0) {
 #ifdef H5T_DEBUG
 	    if (H5DEBUG(T)) {
 		fprintf(H5DEBUG(T), "H5T: unable to initialize no-op "
@@ -8330,7 +8367,7 @@ H5T_path_find(const H5T_t *src, const H5T_t *dst, const char *name,
      * the path.
      */
     if (!table || func) {
-	if (NULL==(path=H5FL_ALLOC(H5T_path_t,1)))
+	if (NULL==(path=H5FL_CALLOC(H5T_path_t)))
 	    HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed for type conversion path");
 	if (name && *name) {
 	    HDstrncpy(path->name, name, H5T_NAMELEN);
@@ -8360,7 +8397,7 @@ H5T_path_find(const H5T_t *src, const H5T_t *dst, const char *name,
 	    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTREGISTER, NULL, "unable to register destination conversion type for query");
 	path->cdata.command = H5T_CONV_INIT;
 	if ((func)(src_id, dst_id, &(path->cdata), (hsize_t)0, 0, 0, NULL, NULL,
-                   H5P_DEFAULT)<0)
+                   H5P_DATASET_XFER_DEFAULT)<0)
 	    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, NULL, "unable to initialize conversion function");
 	if (src_id>=0) H5I_dec_ref(src_id);
 	if (dst_id>=0) H5I_dec_ref(dst_id);
@@ -8388,7 +8425,7 @@ H5T_path_find(const H5T_t *src, const H5T_t *dst, const char *name,
 	    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTREGISTER, NULL, "unable to register conversion types for query");
 	path->cdata.command = H5T_CONV_INIT;
 	if ((H5T_g.soft[i].func) (src_id, dst_id, &(path->cdata),
-                                  (hsize_t)0, 0, 0, NULL, NULL, H5P_DEFAULT)<0) {
+                                  (hsize_t)0, 0, 0, NULL, NULL, H5P_DATASET_XFER_DEFAULT)<0) {
 	    HDmemset (&(path->cdata), 0, sizeof(H5T_cdata_t));
 	    H5E_clear(); /*ignore the error*/
 	} else {
@@ -8432,7 +8469,7 @@ H5T_path_find(const H5T_t *src, const H5T_t *dst, const char *name,
 	H5T_print_stats(table, &nprint/*in,out*/);
 	table->cdata.command = H5T_CONV_FREE;
 	if ((table->func)(FAIL, FAIL, &(table->cdata), (hsize_t)0, 0, 0, NULL, NULL,
-                          H5P_DEFAULT)<0) {
+                          H5P_DATASET_XFER_DEFAULT)<0) {
 #ifdef H5T_DEBUG
 	    if (H5DEBUG(T)) {
 		fprintf(H5DEBUG(T), "H5T: conversion function 0x%08lx free "
@@ -8794,7 +8831,7 @@ H5T_array_create(H5T_t *base, int ndims, const hsize_t dim[/* ndims */],
     assert(dim);
 
     /* Build new type */
-    if (NULL==(ret_value = H5FL_ALLOC(H5T_t,1)))
+    if (NULL==(ret_value = H5FL_CALLOC(H5T_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     ret_value->ent.header = HADDR_UNDEF;
diff --git a/src/H5TB.c b/src/H5TB.c
index 391101f..5f04732 100644
--- a/src/H5TB.c
+++ b/src/H5TB.c
@@ -90,7 +90,7 @@
 
 /* Local Function Prototypes */
 static H5TB_NODE * H5TB_end(H5TB_NODE * root, int side);
-static H5TB_NODE *H5TB_ffind(H5TB_NODE * root, void * key, unsigned fast_compare,
+static H5TB_NODE *H5TB_ffind(H5TB_NODE * root, const void * key, unsigned fast_compare,
     H5TB_NODE ** pp);
 static herr_t H5TB_balance(H5TB_NODE ** root, H5TB_NODE * ptr, int side, int added);
 static H5TB_NODE *H5TB_swapkid(H5TB_NODE ** root, H5TB_NODE * ptr, int side);
@@ -105,12 +105,148 @@ static herr_t H5TB_dumpNode(H5TB_NODE *node, void (*key_dump)(void *,void *),
 /* Declare a free list to manage the H5TB_NODE struct */
 H5FL_DEFINE_STATIC(H5TB_NODE);
 
+/* Declare a free list to manage the H5TB_TREE struct */
+H5FL_DEFINE_STATIC(H5TB_TREE);
+
 #define PABLO_MASK	H5TB_mask
 static int		interface_initialize_g = 0;
 #define INTERFACE_INIT	NULL
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5TB_strcmp
+ *
+ * Purpose:	Key comparison routine for TBBT routines
+ *
+ * Return:	same as strcmp()
+ *
+ * Programmer:	Quincey Koziol
+ *              Wednesday, December 4, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static int
+H5TB_strcmp(const void *k1, const void *k2, int UNUSED cmparg)
+{
+    FUNC_ENTER_NOINIT(H5TB_strcmp);
+
+    assert(k1);
+    assert(k2);
+
+    FUNC_LEAVE(HDstrcmp(k1,k2));
+} /* end H5TB_strcmp() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5TB_addr_cmp
+ *
+ * Purpose:	Key comparison routine for TBBT routines
+ *
+ * Return:	same as H5F_addr_cmp()
+ *
+ * Programmer:	Quincey Koziol
+ *              Friday, December 20, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static int
+H5TB_addr_cmp(const void *k1, const void *k2, int UNUSED cmparg)
+{
+    FUNC_ENTER_NOINIT(H5TB_addr_cmp);
+
+    assert(k1);
+    assert(k2);
+
+    FUNC_LEAVE(H5F_addr_cmp(*(const haddr_t *)k1,*(const haddr_t *)k2));
+} /* end H5TB_addr_cmp() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5TB_int_cmp
+ *
+ * Purpose:	Key comparison routine for TBBT routines
+ *
+ * Return:	same as comparing two integers
+ *
+ * Programmer:	Quincey Koziol
+ *              Friday, December 20, 2002
+ *
+ * Modifications:
+ *
+ *-------------------------------------------------------------------------
+ */
+static int
+H5TB_int_cmp(const void *k1, const void *k2, int UNUSED cmparg)
+{
+    FUNC_ENTER_NOINIT(H5TB_int_cmp);
+
+    assert(k1);
+    assert(k2);
+
+    FUNC_LEAVE(*(const int *)k1 - *(const int *)k2);
+} /* end H5TB_int_cmp() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5TB_fast_dmake
+ *
+ * Purpose:	Wrapper around H5TB_dmake for callers which want to use
+ *              a "fast comparison" key.
+ *
+ * Return:	Success:	Pointer to a valid H5TB tree
+ * 		Failure:	NULL
+ *
+ * Programmer:	Quincey Koziol
+ *              Friday, December 20, 2002
+ *
+ * Modifications:
+ * 	
+ *-------------------------------------------------------------------------
+ */
+H5TB_TREE  *
+H5TB_fast_dmake(unsigned fast_compare)
+{
+    H5TB_cmp_t  compar;         /* Key comparison function */
+    int cmparg;                 /* Key comparison value */
+    H5TB_TREE  *ret_value;      /* Return value */
+
+    FUNC_ENTER_NOAPI(H5TB_fast_dmake, NULL);
+
+    /* Get the corret fast comparison routine */
+    switch(fast_compare) {
+        case H5TB_FAST_HADDR_COMPARE:
+            compar=H5TB_addr_cmp;
+            cmparg=-1;
+            break;
+
+        case H5TB_FAST_INTN_COMPARE:
+            compar=H5TB_int_cmp;
+            cmparg=-1;
+            break;
+
+        case H5TB_FAST_STR_COMPARE:
+            compar=H5TB_strcmp;
+            cmparg=-1;
+            break;
+
+        default:
+            HGOTO_ERROR (H5E_TBBT, H5E_BADVALUE, NULL, "invalid fast comparison type");
+    } /* end switch */
+
+    /* Set return value */
+    if((ret_value=H5TB_dmake(compar,cmparg,fast_compare))==NULL)
+        HGOTO_ERROR (H5E_TBBT, H5E_CANTCREATE, NULL, "can't create TBBT");
+
+done:
+    FUNC_LEAVE (ret_value);
+}   /* end H5TB_fast_dmake() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5TB_dmake
  *
  * Purpose:	Allocates and initializes an empty threaded, balanced, binary tree
@@ -192,7 +328,7 @@ H5TB_dmake(H5TB_cmp_t cmp, int arg, unsigned fast_compare)
 
     FUNC_ENTER_NOAPI(H5TB_dmake, NULL);
 
-    if (NULL == (tree = H5MM_malloc(sizeof(H5TB_TREE))))
+    if (NULL == (tree = H5FL_MALLOC(H5TB_TREE)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
 
     tree->root = NULL;
@@ -234,7 +370,7 @@ done:
  *-------------------------------------------------------------------------
  */
 H5TB_NODE  *
-H5TB_dfind(H5TB_TREE * tree, void * key, H5TB_NODE ** pp)
+H5TB_dfind(H5TB_TREE * tree, const void * key, H5TB_NODE ** pp)
 {
     H5TB_NODE *ret_value;
 
@@ -242,10 +378,16 @@ H5TB_dfind(H5TB_TREE * tree, void * key, H5TB_NODE ** pp)
 
     assert(tree);
 
-    if(tree->fast_compare!=0)
-        ret_value=H5TB_ffind(tree->root, key, tree->fast_compare, pp);
-    else
-        ret_value=H5TB_find(tree->root, key, tree->compar, tree->cmparg, pp);
+    if(tree->root)
+        if(tree->fast_compare!=0)
+            ret_value=H5TB_ffind(tree->root, key, tree->fast_compare, pp);
+        else
+            ret_value=H5TB_find(tree->root, key, tree->compar, tree->cmparg, pp);
+    else {
+        if (NULL != pp)
+            *pp = NULL;
+        ret_value=NULL;
+    } /* end else */
 
 done:
     FUNC_LEAVE (ret_value);
@@ -280,7 +422,7 @@ done:
  *-------------------------------------------------------------------------
  */
 H5TB_NODE  *
-H5TB_find(H5TB_NODE * root, void * key,
+H5TB_find(H5TB_NODE * root, const void * key,
      H5TB_cmp_t compar, int arg, H5TB_NODE ** pp)
 {
     H5TB_NODE  *ptr = root;
@@ -461,7 +603,7 @@ H5TB_index(H5TB_NODE * root, unsigned indx)
     if (NULL != ptr) {
       /* Termination condition is if the index equals the number of children on
          out left plus the current node */
-        while (ptr != NULL && indx != ((unsigned) LeftCnt(ptr)) + 1 ) {
+        while (ptr != NULL && indx != ((unsigned) LeftCnt(ptr)) ) {
             if (indx <= (unsigned) LeftCnt(ptr)) {
                 ptr = ptr->Lchild;
               } /* end if */
@@ -564,7 +706,7 @@ H5TB_ins(H5TB_NODE ** root, void * item, void * key, H5TB_cmp_t compar, int arg)
 
     if (NULL != H5TB_find(*root, (key ? key : item), compar, arg, &parent))
         HGOTO_ERROR (H5E_TBBT, H5E_EXISTS, NULL, "node already in tree");
-    if (NULL == (ptr = H5FL_ALLOC(H5TB_NODE,0)))
+    if (NULL == (ptr = H5FL_MALLOC(H5TB_NODE)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed");
     ptr->data = item;
     ptr->key = key ? key : item;
@@ -760,12 +902,13 @@ H5TB_rem(H5TB_NODE ** root, H5TB_NODE * node, void * *kp)
     H5FL_FREE(H5TB_NODE,leaf);
     H5TB_balance(root, par, side, -1);
 
-    ((H5TB_TREE *) root)->count--;
-
     /* Set return value */
     ret_value=data;
 
 done:
+    if(ret_value)
+        ((H5TB_TREE *) root)->count--;
+
     FUNC_LEAVE(ret_value);
 }   /* end H5TB_rem() */
 
@@ -945,7 +1088,7 @@ H5TB_dfree(H5TB_TREE * tree, void(*fd) (void * /* item */), void(*fk) (void * /*
         H5TB_free(&tree->root, fd, fk);
 
         /* Free the tree root */
-        H5MM_xfree(tree);
+        H5FL_FREE(H5TB_TREE,tree);
     } /* end if */
 
 done:
@@ -1254,7 +1397,7 @@ done:
 /* This routine is based on tbbtfind (fix bugs in both places!) */
 /* Returns a pointer to the found node (or NULL) */
 static H5TB_NODE  *
-H5TB_ffind(H5TB_NODE * root, void * key, unsigned fast_compare, H5TB_NODE ** pp)
+H5TB_ffind(H5TB_NODE * root, const void * key, unsigned fast_compare, H5TB_NODE ** pp)
 {
     H5TB_NODE  *ptr = root;
     H5TB_NODE  *parent = NULL;
@@ -1267,7 +1410,7 @@ H5TB_ffind(H5TB_NODE * root, void * key, unsigned fast_compare, H5TB_NODE ** pp)
     switch(fast_compare) {
         case H5TB_FAST_HADDR_COMPARE:
             if (ptr) {
-                while (0 != (cmp = H5F_addr_cmp(*(haddr_t *)key,*(haddr_t *)ptr->key))) {
+                while (0 != (cmp = H5F_addr_cmp(*(const haddr_t *)key,*(haddr_t *)ptr->key))) {
                       parent = ptr;
                       side = (cmp < 0) ? LEFT : RIGHT;
                       if (!HasChild(ptr, side))
@@ -1284,7 +1427,24 @@ H5TB_ffind(H5TB_NODE * root, void * key, unsigned fast_compare, H5TB_NODE ** pp)
 
         case H5TB_FAST_INTN_COMPARE:
             if (ptr) {
-                while (0 != (cmp = (*(int *)key - *(int *)ptr->key))) {
+                while (0 != (cmp = (*(const int *)key - *(int *)ptr->key))) {
+                      parent = ptr;
+                      side = (cmp < 0) ? LEFT : RIGHT;
+                      if (!HasChild(ptr, side))
+                          break;
+                      ptr = ptr->link[side];
+                  } /* end while */
+              } /* end if */
+            if (NULL != pp)
+                *pp = parent;
+
+            /* Set return value */
+            ret_value= (0 == cmp) ? ptr : NULL;
+            break;
+
+        case H5TB_FAST_STR_COMPARE:
+            if (ptr) {
+                while (0 != (cmp = HDstrcmp(key,ptr->key))) {
                       parent = ptr;
                       side = (cmp < 0) ? LEFT : RIGHT;
                       if (!HasChild(ptr, side))
diff --git a/src/H5TBprivate.h b/src/H5TBprivate.h
index f1d6bef..9c2ccc5 100644
--- a/src/H5TBprivate.h
+++ b/src/H5TBprivate.h
@@ -23,7 +23,7 @@
 #endif /* LATER */
 
 /* Typedef for key comparison function */
-typedef int (*H5TB_cmp_t)(void *k1, void *k2, int cmparg);
+typedef int (*H5TB_cmp_t)(const void *k1, const void *k2, int cmparg);
 
 /* Shortcut macros for links */
 # define   PARENT  0
@@ -89,6 +89,10 @@ typedef struct H5TB_tree
 /* Define the "fast compare" values */
 #define H5TB_FAST_HADDR_COMPARE    1
 #define H5TB_FAST_INTN_COMPARE     2
+#define H5TB_FAST_STR_COMPARE      3
+
+/* Define an access macro for getting a node's data */
+#define H5TB_NODE_DATA(n)       ((n)->data)
 
 #if defined c_plusplus || defined __cplusplus
 extern      "C"
@@ -96,8 +100,9 @@ extern      "C"
 #endif                          /* c_plusplus || __cplusplus */
 
 H5_DLL H5TB_TREE  *H5TB_dmake (H5TB_cmp_t cmp, int arg, unsigned fast_compare);
-H5_DLL H5TB_NODE  *H5TB_dfind (H5TB_TREE * tree, void * key, H5TB_NODE ** pp);
-H5_DLL H5TB_NODE  *H5TB_find(H5TB_NODE * root, void * key, H5TB_cmp_t cmp,
+H5_DLL H5TB_TREE  *H5TB_fast_dmake (unsigned fast_compare);
+H5_DLL H5TB_NODE  *H5TB_dfind (H5TB_TREE * tree, const void * key, H5TB_NODE ** pp);
+H5_DLL H5TB_NODE  *H5TB_find(H5TB_NODE * root, const void * key, H5TB_cmp_t cmp,
                  int arg, H5TB_NODE ** pp);
 H5_DLL H5TB_NODE  *H5TB_dless (H5TB_TREE * tree, void * key, H5TB_NODE ** pp);
 H5_DLL H5TB_NODE  *H5TB_less (H5TB_NODE * root, void * key, H5TB_cmp_t cmp,
diff --git a/src/H5Tconv.c b/src/H5Tconv.c
index 0444d2c..7f389ec 100644
--- a/src/H5Tconv.c
+++ b/src/H5Tconv.c
@@ -283,8 +283,8 @@ H5FL_BLK_DEFINE_STATIC(array_seq);
     case H5T_CONV_INIT:							      \
 	/* Sanity check and initialize statistics */			      \
 	cdata->need_bkg = H5T_BKG_NO;					      \
-	if (NULL==(st=H5I_object_verify(src_id,H5I_DATATYPE)) ||	      \
-                NULL==(dt=H5I_object_verify(dst_id,H5I_DATATYPE))) {	      \
+	if (NULL==(st=H5I_object(src_id)) ||	                	      \
+                NULL==(dt=H5I_object(dst_id))) {	        	      \
 	    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL,		      \
 			  "unable to dereference data type object ID");	      \
 	}								      \
@@ -292,13 +292,13 @@ H5FL_BLK_DEFINE_STATIC(array_seq);
 	    HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL,		      \
 			  "disagreement about data type size");		      \
 	}								      \
-    CI_ALLOC_PRIV           \
+	CI_ALLOC_PRIV	                                                      \
 	break;								      \
 									      \
     case H5T_CONV_FREE:							      \
 	/* Print and free statistics */					      \
 	CI_PRINT_STATS(STYPE,DTYPE);					      \
-    CI_FREE_PRIV                                        \
+	CI_FREE_PRIV	                                                      \
 	break;								      \
 									      \
     case H5T_CONV_CONV:							      \
@@ -488,8 +488,8 @@ H5T_conv_order_opt(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata,
     switch (cdata->command) {
     case H5T_CONV_INIT:
 	/* Capability query */
-	if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+	if (NULL == (src = H5I_object(src_id)) ||
+                NULL == (dst = H5I_object(dst_id)))
 	    HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 	if (src->size != dst->size ||
                 0 != src->u.atomic.offset ||
@@ -528,8 +528,8 @@ H5T_conv_order_opt(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata,
 
     case H5T_CONV_CONV:
 	/* The conversion */
-	if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+	if (NULL == (src = H5I_object(src_id)) ||
+                NULL == (dst = H5I_object(dst_id)))
 	    HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
         buf_stride = buf_stride ? buf_stride : src->size;
@@ -872,8 +872,8 @@ H5T_conv_order(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
     switch (cdata->command) {
     case H5T_CONV_INIT:
 	/* Capability query */
-	if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+	if (NULL == (src = H5I_object(src_id)) ||
+                NULL == (dst = H5I_object(dst_id)))
 	    HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 	if (src->size != dst->size || 0 != src->u.atomic.offset ||
                 0 != dst->u.atomic.offset ||
@@ -909,8 +909,8 @@ H5T_conv_order(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
 
     case H5T_CONV_CONV:
 	/* The conversion */
-	if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+	if (NULL == (src = H5I_object(src_id)) ||
+                NULL == (dst = H5I_object(dst_id)))
 	    HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
         buf_stride = buf_stride ? buf_stride : src->size;
@@ -974,8 +974,8 @@ H5T_conv_b_b(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
     switch(cdata->command) {
         case H5T_CONV_INIT:
             /* Capability query */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             if (H5T_ORDER_LE!=src->u.atomic.order &&
                     H5T_ORDER_BE!=src->u.atomic.order)
@@ -991,8 +991,8 @@ H5T_conv_b_b(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
 
         case H5T_CONV_CONV:
             /* Get the data types */
-            if (NULL==(src=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==(dst=H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL==(src=H5I_object(src_id)) ||
+                    NULL==(dst=H5I_object(dst_id)))
                 HGOTO_ERROR (H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
             /*
@@ -1339,8 +1339,8 @@ H5T_conv_struct(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
              * otherwise initialize the `priv' field of `cdata' with information
              * that remains (almost) constant for this conversion path.
              */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             assert (H5T_COMPOUND==src->type);
             assert (H5T_COMPOUND==dst->type);
@@ -1364,8 +1364,8 @@ H5T_conv_struct(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
             /*
              * Conversion.
              */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             assert (priv);
             assert (bkg && cdata->need_bkg);
@@ -1571,8 +1571,8 @@ H5T_conv_struct_opt(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata,
              * otherwise initialize the `priv' field of `cdata' with information
              * that remains (almost) constant for this conversion path.
              */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             assert (H5T_COMPOUND==src->type);
             assert (H5T_COMPOUND==dst->type);
@@ -1638,8 +1638,8 @@ H5T_conv_struct_opt(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata,
             /*
              * Conversion.
              */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
             /* Update cached data if necessary */
@@ -1934,8 +1934,8 @@ H5T_conv_enum(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
              * the `priv' field of `cdata' with information about the underlying
              * integer conversion.
              */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             assert (H5T_ENUM==src->type);
             assert (H5T_ENUM==dst->type);
@@ -1959,8 +1959,8 @@ H5T_conv_enum(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
             break;
 
         case H5T_CONV_CONV:
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             assert (H5T_ENUM==src->type);
             assert (H5T_ENUM==dst->type);
@@ -2132,8 +2132,8 @@ H5T_conv_vlen(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
              * information that remains (almost) constant for this
              * conversion path.
              */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             assert (H5T_VLEN==src->type);
             assert (H5T_VLEN==dst->type);
@@ -2151,8 +2151,8 @@ H5T_conv_vlen(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
             /*
              * Conversion.
              */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
             /*
@@ -2209,7 +2209,7 @@ H5T_conv_vlen(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
 
             /* Get initial conversion buffer */
             conv_buf_size=MAX(src_base_size,dst_base_size);
-            if ((conv_buf=H5FL_BLK_ALLOC(vlen_seq,conv_buf_size,1))==NULL)
+            if ((conv_buf=H5FL_BLK_CALLOC(vlen_seq,conv_buf_size))==NULL)
                 HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for type conversion");
 
             /* Set up conversion path for base elements */
@@ -2225,7 +2225,7 @@ H5T_conv_vlen(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
             if(tpath->cdata.need_bkg||H5T_detect_class(dst->parent,H5T_VLEN)) {
                 /* Set up initial background buffer */
                 tmp_buf_size=MAX(src_base_size,dst_base_size);
-                if ((tmp_buf=H5FL_BLK_ALLOC(vlen_seq,tmp_buf_size,1))==NULL)
+                if ((tmp_buf=H5FL_BLK_CALLOC(vlen_seq,tmp_buf_size))==NULL)
                     HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for type conversion");
             } /* end if */
     
@@ -2340,13 +2340,6 @@ H5T_conv_vlen(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
                 } /* end if */
             }
 
-            /* Release the conversion buffer (always allocated) */
-            H5FL_BLK_FREE(vlen_seq,conv_buf);
-
-            /* Release the background buffer, if we have one */
-            if(tmp_buf!=NULL)
-                H5FL_BLK_FREE(vlen_seq,tmp_buf);
-
             /* Release the temporary datatype IDs used */
             if (tsrc_id >= 0)
                 H5I_dec_ref(tsrc_id);
@@ -2359,6 +2352,13 @@ H5T_conv_vlen(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
     }   /* end switch */
     
 done:
+    /* Release the conversion buffer (always allocated, except on errors) */
+    if(conv_buf!=NULL)
+        H5FL_BLK_FREE(vlen_seq,conv_buf);
+    /* Release the background buffer, if we have one */
+    if(tmp_buf!=NULL)
+        H5FL_BLK_FREE(vlen_seq,tmp_buf);
+
     FUNC_LEAVE (ret_value);
 }
 
@@ -2407,8 +2407,8 @@ H5T_conv_array(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
              * information that remains (almost) constant for this
              * conversion path.
              */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             assert (H5T_ARRAY==src->type);
             assert (H5T_ARRAY==dst->type);
@@ -2438,8 +2438,8 @@ H5T_conv_array(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
             /*
              * Conversion.
              */
-            if (NULL == (src = H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL == (dst = H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL == (src = H5I_object(src_id)) ||
+                    NULL == (dst = H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
             /*
@@ -2477,7 +2477,7 @@ H5T_conv_array(hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
             if(tpath->cdata.need_bkg) {
                 /* Allocate background buffer */
                 bkg_buf_size=src->u.array.nelem*MAX(src->size,dst->size);
-                if ((bkg_buf=H5FL_BLK_ALLOC(array_seq,bkg_buf_size,0))==NULL)
+                if ((bkg_buf=H5FL_BLK_MALLOC(array_seq,bkg_buf_size))==NULL)
                     HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed for type conversion");
             } /* end if */
 
@@ -2560,8 +2560,8 @@ H5T_conv_i_i (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
 
     switch (cdata->command) {
         case H5T_CONV_INIT:
-            if (NULL==(src=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==(dst=H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL==(src=H5I_object(src_id)) ||
+                    NULL==(dst=H5I_object(dst_id)))
                 HGOTO_ERROR (H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             if (H5T_ORDER_LE!=src->u.atomic.order &&
                     H5T_ORDER_BE!=src->u.atomic.order)
@@ -2579,8 +2579,8 @@ H5T_conv_i_i (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
 
         case H5T_CONV_CONV:
             /* Get the data types */
-            if (NULL==(src=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==(dst=H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL==(src=H5I_object(src_id)) ||
+                    NULL==(dst=H5I_object(dst_id)))
                 HGOTO_ERROR (H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
             /*
@@ -2899,8 +2899,8 @@ H5T_conv_f_f (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
 
     switch (cdata->command) {
         case H5T_CONV_INIT:
-            if (NULL==(src_p=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==(dst_p=H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL==(src_p=H5I_object(src_id)) ||
+                    NULL==(dst_p=H5I_object(dst_id)))
                 HGOTO_ERROR (H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             src = src_p->u.atomic;
             dst = dst_p->u.atomic;
@@ -2920,8 +2920,8 @@ H5T_conv_f_f (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
 
         case H5T_CONV_CONV:
             /* Get the data types */
-            if (NULL==(src_p=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==(dst_p=H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL==(src_p=H5I_object(src_id)) ||
+                    NULL==(dst_p=H5I_object(dst_id)))
                 HGOTO_ERROR (H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             src = src_p->u.atomic;
             dst = dst_p->u.atomic;
@@ -3308,8 +3308,8 @@ H5T_conv_s_s (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
 
     switch (cdata->command) {
         case H5T_CONV_INIT:
-            if (NULL==(src=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==(dst=H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL==(src=H5I_object(src_id)) ||
+                    NULL==(dst=H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             if (8*src->size != src->u.atomic.prec || 8*dst->size != dst->u.atomic.prec)
                 HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "bad precision");
@@ -3328,8 +3328,8 @@ H5T_conv_s_s (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata, hsize_t nelmts,
 
         case H5T_CONV_CONV:
             /* Get the data types */
-            if (NULL==(src=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==(dst=H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL==(src=H5I_object(src_id)) ||
+                    NULL==(dst=H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
             /*
@@ -6473,8 +6473,8 @@ H5T_conv_float_double (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata,
     switch (cdata->command) {
         case H5T_CONV_INIT:
             cdata->need_bkg = H5T_BKG_NO;
-            if (NULL==(st=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==(dt=H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL==(st=H5I_object(src_id)) ||
+                    NULL==(dt=H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to dereference data type object ID");
             if (st->size!=sizeof(float) || dt->size!=sizeof(double))
                 HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "disagreement about data type size");
@@ -6593,8 +6593,8 @@ H5T_conv_double_float (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata,
     switch (cdata->command) {
         case H5T_CONV_INIT:
             cdata->need_bkg = H5T_BKG_NO;
-            if (NULL==(st=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==(dt=H5I_object_verify(dst_id,H5I_DATATYPE)))
+            if (NULL==(st=H5I_object(src_id)) ||
+                    NULL==(dt=H5I_object(dst_id)))
                 HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "unable to dereference data type object ID");
             if (st->size!=sizeof(double) || dt->size!=sizeof(float))
                 HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, FAIL, "disagreement about data type size");
@@ -6731,8 +6731,8 @@ H5T_conv_i32le_f64le (hid_t src_id, hid_t dst_id, H5T_cdata_t *cdata,
 
         case H5T_CONV_CONV:
             /* The conversion */
-            if (NULL==(src=H5I_object_verify(src_id,H5I_DATATYPE)) ||
-                    NULL==H5I_object_verify(dst_id,H5I_DATATYPE))
+            if (NULL==(src=H5I_object(src_id)) ||
+                    NULL==H5I_object(dst_id))
                 HGOTO_ERROR (H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
             
             s = (uint8_t*)buf + (buf_stride?buf_stride:4)*(nelmts-1);
diff --git a/src/H5Tprivate.h b/src/H5Tprivate.h
index d9f4520..7491749 100644
--- a/src/H5Tprivate.h
+++ b/src/H5Tprivate.h
@@ -101,6 +101,7 @@ H5_DLL H5T_t *H5T_create(H5T_class_t type, size_t size);
 H5_DLL H5T_t *H5T_copy(const H5T_t *old_dt, H5T_copy_t method);
 H5_DLL herr_t H5T_commit(H5G_entry_t *loc, const char *name, H5T_t *type);
 H5_DLL herr_t H5T_lock(H5T_t *dt, hbool_t immutable);
+H5_DLL herr_t H5T_free(H5T_t *dt);
 H5_DLL herr_t H5T_close(H5T_t *dt);
 H5_DLL herr_t H5T_unregister(H5T_pers_t pers, const char *name, H5T_t *src,
                 H5T_t *dst, H5T_conv_t func);
diff --git a/src/H5Tpublic.h b/src/H5Tpublic.h
index 2bfc7da..a96d2bb 100644
--- a/src/H5Tpublic.h
+++ b/src/H5Tpublic.h
@@ -196,13 +196,21 @@ typedef herr_t (*H5T_overflow_t)(hid_t src_id, hid_t dst_id,
 extern "C" {
 #endif
 
+/* When this header is included from H5Tprivate.h, don't make calls to H5open() */
+#undef H5OPEN
+#ifndef _H5Tprivate_H
+#define H5OPEN          H5open(),
+#else   /* _H5Tprivate_H */
+#define H5OPEN
+#endif  /* _H5Tprivate_H */
+
 /*
  * The IEEE floating point types in various byte orders.
  */
-#define H5T_IEEE_F32BE		(H5open(), H5T_IEEE_F32BE_g)
-#define H5T_IEEE_F32LE		(H5open(), H5T_IEEE_F32LE_g)
-#define H5T_IEEE_F64BE		(H5open(), H5T_IEEE_F64BE_g)
-#define H5T_IEEE_F64LE		(H5open(), H5T_IEEE_F64LE_g)
+#define H5T_IEEE_F32BE		(H5OPEN H5T_IEEE_F32BE_g)
+#define H5T_IEEE_F32LE		(H5OPEN H5T_IEEE_F32LE_g)
+#define H5T_IEEE_F64BE		(H5OPEN H5T_IEEE_F64BE_g)
+#define H5T_IEEE_F64LE		(H5OPEN H5T_IEEE_F64LE_g)
 H5_DLLVAR hid_t H5T_IEEE_F32BE_g;
 H5_DLLVAR hid_t H5T_IEEE_F32LE_g;
 H5_DLLVAR hid_t H5T_IEEE_F64BE_g;
@@ -212,32 +220,32 @@ H5_DLLVAR hid_t H5T_IEEE_F64LE_g;
  * These are "standard" types.  For instance, signed (2's complement) and
  * unsigned integers of various sizes and byte orders.
  */
-#define H5T_STD_I8BE		(H5open(), H5T_STD_I8BE_g)
-#define H5T_STD_I8LE		(H5open(), H5T_STD_I8LE_g)
-#define H5T_STD_I16BE		(H5open(), H5T_STD_I16BE_g)
-#define H5T_STD_I16LE		(H5open(), H5T_STD_I16LE_g)
-#define H5T_STD_I32BE		(H5open(), H5T_STD_I32BE_g)
-#define H5T_STD_I32LE		(H5open(), H5T_STD_I32LE_g)
-#define H5T_STD_I64BE		(H5open(), H5T_STD_I64BE_g)
-#define H5T_STD_I64LE		(H5open(), H5T_STD_I64LE_g)
-#define H5T_STD_U8BE		(H5open(), H5T_STD_U8BE_g)
-#define H5T_STD_U8LE		(H5open(), H5T_STD_U8LE_g)
-#define H5T_STD_U16BE		(H5open(), H5T_STD_U16BE_g)
-#define H5T_STD_U16LE		(H5open(), H5T_STD_U16LE_g)
-#define H5T_STD_U32BE		(H5open(), H5T_STD_U32BE_g)
-#define H5T_STD_U32LE		(H5open(), H5T_STD_U32LE_g)
-#define H5T_STD_U64BE		(H5open(), H5T_STD_U64BE_g)
-#define H5T_STD_U64LE		(H5open(), H5T_STD_U64LE_g)
-#define H5T_STD_B8BE		(H5open(), H5T_STD_B8BE_g)
-#define H5T_STD_B8LE		(H5open(), H5T_STD_B8LE_g)
-#define H5T_STD_B16BE		(H5open(), H5T_STD_B16BE_g)
-#define H5T_STD_B16LE		(H5open(), H5T_STD_B16LE_g)
-#define H5T_STD_B32BE		(H5open(), H5T_STD_B32BE_g)
-#define H5T_STD_B32LE		(H5open(), H5T_STD_B32LE_g)
-#define H5T_STD_B64BE		(H5open(), H5T_STD_B64BE_g)
-#define H5T_STD_B64LE		(H5open(), H5T_STD_B64LE_g)
-#define H5T_STD_REF_OBJ	    (H5open(), H5T_STD_REF_OBJ_g)
-#define H5T_STD_REF_DSETREG (H5open(), H5T_STD_REF_DSETREG_g)
+#define H5T_STD_I8BE		(H5OPEN H5T_STD_I8BE_g)
+#define H5T_STD_I8LE		(H5OPEN H5T_STD_I8LE_g)
+#define H5T_STD_I16BE		(H5OPEN H5T_STD_I16BE_g)
+#define H5T_STD_I16LE		(H5OPEN H5T_STD_I16LE_g)
+#define H5T_STD_I32BE		(H5OPEN H5T_STD_I32BE_g)
+#define H5T_STD_I32LE		(H5OPEN H5T_STD_I32LE_g)
+#define H5T_STD_I64BE		(H5OPEN H5T_STD_I64BE_g)
+#define H5T_STD_I64LE		(H5OPEN H5T_STD_I64LE_g)
+#define H5T_STD_U8BE		(H5OPEN H5T_STD_U8BE_g)
+#define H5T_STD_U8LE		(H5OPEN H5T_STD_U8LE_g)
+#define H5T_STD_U16BE		(H5OPEN H5T_STD_U16BE_g)
+#define H5T_STD_U16LE		(H5OPEN H5T_STD_U16LE_g)
+#define H5T_STD_U32BE		(H5OPEN H5T_STD_U32BE_g)
+#define H5T_STD_U32LE		(H5OPEN H5T_STD_U32LE_g)
+#define H5T_STD_U64BE		(H5OPEN H5T_STD_U64BE_g)
+#define H5T_STD_U64LE		(H5OPEN H5T_STD_U64LE_g)
+#define H5T_STD_B8BE		(H5OPEN H5T_STD_B8BE_g)
+#define H5T_STD_B8LE		(H5OPEN H5T_STD_B8LE_g)
+#define H5T_STD_B16BE		(H5OPEN H5T_STD_B16BE_g)
+#define H5T_STD_B16LE		(H5OPEN H5T_STD_B16LE_g)
+#define H5T_STD_B32BE		(H5OPEN H5T_STD_B32BE_g)
+#define H5T_STD_B32LE		(H5OPEN H5T_STD_B32LE_g)
+#define H5T_STD_B64BE		(H5OPEN H5T_STD_B64BE_g)
+#define H5T_STD_B64LE		(H5OPEN H5T_STD_B64LE_g)
+#define H5T_STD_REF_OBJ	        (H5OPEN H5T_STD_REF_OBJ_g)
+#define H5T_STD_REF_DSETREG     (H5OPEN H5T_STD_REF_DSETREG_g)
 H5_DLLVAR hid_t H5T_STD_I8BE_g;
 H5_DLLVAR hid_t H5T_STD_I8LE_g;
 H5_DLLVAR hid_t H5T_STD_I16BE_g;
@@ -268,10 +276,10 @@ H5_DLLVAR hid_t H5T_STD_REF_DSETREG_g;
 /*
  * Types which are particular to Unix.
  */
-#define H5T_UNIX_D32BE		(H5open(), H5T_UNIX_D32BE_g)
-#define H5T_UNIX_D32LE		(H5open(), H5T_UNIX_D32LE_g)
-#define H5T_UNIX_D64BE		(H5open(), H5T_UNIX_D64BE_g)
-#define H5T_UNIX_D64LE		(H5open(), H5T_UNIX_D64LE_g)
+#define H5T_UNIX_D32BE		(H5OPEN H5T_UNIX_D32BE_g)
+#define H5T_UNIX_D32LE		(H5OPEN H5T_UNIX_D32LE_g)
+#define H5T_UNIX_D64BE		(H5OPEN H5T_UNIX_D64BE_g)
+#define H5T_UNIX_D64LE		(H5OPEN H5T_UNIX_D64LE_g)
 H5_DLLVAR hid_t H5T_UNIX_D32BE_g;
 H5_DLLVAR hid_t H5T_UNIX_D32LE_g;
 H5_DLLVAR hid_t H5T_UNIX_D64BE_g;
@@ -281,13 +289,13 @@ H5_DLLVAR hid_t H5T_UNIX_D64LE_g;
  * Types particular to the C language.  String types use `bytes' instead
  * of `bits' as their size.
  */
-#define H5T_C_S1		(H5open(), H5T_C_S1_g)
+#define H5T_C_S1		(H5OPEN H5T_C_S1_g)
 H5_DLLVAR hid_t H5T_C_S1_g;
 
 /*
  * Types particular to Fortran.
  */
-#define H5T_FORTRAN_S1		(H5open(), H5T_FORTRAN_S1_g)
+#define H5T_FORTRAN_S1		(H5OPEN H5T_FORTRAN_S1_g)
 H5_DLLVAR hid_t H5T_FORTRAN_S1_g;
 
 /*
@@ -357,29 +365,29 @@ H5_DLLVAR hid_t H5T_FORTRAN_S1_g;
  * same as `LONG' and `DOUBLE' respectively.
  */
 #define H5T_NATIVE_CHAR		(CHAR_MIN?H5T_NATIVE_SCHAR:H5T_NATIVE_UCHAR)
-#define H5T_NATIVE_SCHAR        (H5open(), H5T_NATIVE_SCHAR_g)
-#define H5T_NATIVE_UCHAR        (H5open(), H5T_NATIVE_UCHAR_g)
-#define H5T_NATIVE_SHORT        (H5open(), H5T_NATIVE_SHORT_g)
-#define H5T_NATIVE_USHORT       (H5open(), H5T_NATIVE_USHORT_g)
-#define H5T_NATIVE_INT          (H5open(), H5T_NATIVE_INT_g)
-#define H5T_NATIVE_UINT         (H5open(), H5T_NATIVE_UINT_g)
-#define H5T_NATIVE_LONG         (H5open(), H5T_NATIVE_LONG_g)
-#define H5T_NATIVE_ULONG        (H5open(), H5T_NATIVE_ULONG_g)
-#define H5T_NATIVE_LLONG        (H5open(), H5T_NATIVE_LLONG_g)
-#define H5T_NATIVE_ULLONG       (H5open(), H5T_NATIVE_ULLONG_g)
-#define H5T_NATIVE_FLOAT        (H5open(), H5T_NATIVE_FLOAT_g)
-#define H5T_NATIVE_DOUBLE       (H5open(), H5T_NATIVE_DOUBLE_g)
-#define H5T_NATIVE_LDOUBLE	(H5open(), H5T_NATIVE_LDOUBLE_g)
-#define H5T_NATIVE_B8		(H5open(), H5T_NATIVE_B8_g)
-#define H5T_NATIVE_B16		(H5open(), H5T_NATIVE_B16_g)
-#define H5T_NATIVE_B32		(H5open(), H5T_NATIVE_B32_g)
-#define H5T_NATIVE_B64		(H5open(), H5T_NATIVE_B64_g)
-#define H5T_NATIVE_OPAQUE       (H5open(), H5T_NATIVE_OPAQUE_g)
-#define H5T_NATIVE_HADDR	(H5open(), H5T_NATIVE_HADDR_g)
-#define H5T_NATIVE_HSIZE	(H5open(), H5T_NATIVE_HSIZE_g)
-#define H5T_NATIVE_HSSIZE	(H5open(), H5T_NATIVE_HSSIZE_g)
-#define H5T_NATIVE_HERR		(H5open(), H5T_NATIVE_HERR_g)
-#define H5T_NATIVE_HBOOL	(H5open(), H5T_NATIVE_HBOOL_g)
+#define H5T_NATIVE_SCHAR        (H5OPEN H5T_NATIVE_SCHAR_g)
+#define H5T_NATIVE_UCHAR        (H5OPEN H5T_NATIVE_UCHAR_g)
+#define H5T_NATIVE_SHORT        (H5OPEN H5T_NATIVE_SHORT_g)
+#define H5T_NATIVE_USHORT       (H5OPEN H5T_NATIVE_USHORT_g)
+#define H5T_NATIVE_INT          (H5OPEN H5T_NATIVE_INT_g)
+#define H5T_NATIVE_UINT         (H5OPEN H5T_NATIVE_UINT_g)
+#define H5T_NATIVE_LONG         (H5OPEN H5T_NATIVE_LONG_g)
+#define H5T_NATIVE_ULONG        (H5OPEN H5T_NATIVE_ULONG_g)
+#define H5T_NATIVE_LLONG        (H5OPEN H5T_NATIVE_LLONG_g)
+#define H5T_NATIVE_ULLONG       (H5OPEN H5T_NATIVE_ULLONG_g)
+#define H5T_NATIVE_FLOAT        (H5OPEN H5T_NATIVE_FLOAT_g)
+#define H5T_NATIVE_DOUBLE       (H5OPEN H5T_NATIVE_DOUBLE_g)
+#define H5T_NATIVE_LDOUBLE	(H5OPEN H5T_NATIVE_LDOUBLE_g)
+#define H5T_NATIVE_B8		(H5OPEN H5T_NATIVE_B8_g)
+#define H5T_NATIVE_B16		(H5OPEN H5T_NATIVE_B16_g)
+#define H5T_NATIVE_B32		(H5OPEN H5T_NATIVE_B32_g)
+#define H5T_NATIVE_B64		(H5OPEN H5T_NATIVE_B64_g)
+#define H5T_NATIVE_OPAQUE       (H5OPEN H5T_NATIVE_OPAQUE_g)
+#define H5T_NATIVE_HADDR	(H5OPEN H5T_NATIVE_HADDR_g)
+#define H5T_NATIVE_HSIZE	(H5OPEN H5T_NATIVE_HSIZE_g)
+#define H5T_NATIVE_HSSIZE	(H5OPEN H5T_NATIVE_HSSIZE_g)
+#define H5T_NATIVE_HERR		(H5OPEN H5T_NATIVE_HERR_g)
+#define H5T_NATIVE_HBOOL	(H5OPEN H5T_NATIVE_HBOOL_g)
 H5_DLLVAR hid_t H5T_NATIVE_SCHAR_g;
 H5_DLLVAR hid_t H5T_NATIVE_UCHAR_g;
 H5_DLLVAR hid_t H5T_NATIVE_SHORT_g;
@@ -405,12 +413,12 @@ H5_DLLVAR hid_t H5T_NATIVE_HERR_g;
 H5_DLLVAR hid_t H5T_NATIVE_HBOOL_g;
 
 /* C9x integer types */
-#define H5T_NATIVE_INT8			(H5open(), H5T_NATIVE_INT8_g)
-#define H5T_NATIVE_UINT8		(H5open(), H5T_NATIVE_UINT8_g)
-#define H5T_NATIVE_INT_LEAST8		(H5open(), H5T_NATIVE_INT_LEAST8_g)
-#define H5T_NATIVE_UINT_LEAST8		(H5open(), H5T_NATIVE_UINT_LEAST8_g)
-#define H5T_NATIVE_INT_FAST8 		(H5open(), H5T_NATIVE_INT_FAST8_g)
-#define H5T_NATIVE_UINT_FAST8		(H5open(), H5T_NATIVE_UINT_FAST8_g)
+#define H5T_NATIVE_INT8			(H5OPEN H5T_NATIVE_INT8_g)
+#define H5T_NATIVE_UINT8		(H5OPEN H5T_NATIVE_UINT8_g)
+#define H5T_NATIVE_INT_LEAST8		(H5OPEN H5T_NATIVE_INT_LEAST8_g)
+#define H5T_NATIVE_UINT_LEAST8		(H5OPEN H5T_NATIVE_UINT_LEAST8_g)
+#define H5T_NATIVE_INT_FAST8 		(H5OPEN H5T_NATIVE_INT_FAST8_g)
+#define H5T_NATIVE_UINT_FAST8		(H5OPEN H5T_NATIVE_UINT_FAST8_g)
 H5_DLLVAR hid_t H5T_NATIVE_INT8_g;
 H5_DLLVAR hid_t H5T_NATIVE_UINT8_g;
 H5_DLLVAR hid_t H5T_NATIVE_INT_LEAST8_g;
@@ -418,12 +426,12 @@ H5_DLLVAR hid_t H5T_NATIVE_UINT_LEAST8_g;
 H5_DLLVAR hid_t H5T_NATIVE_INT_FAST8_g;
 H5_DLLVAR hid_t H5T_NATIVE_UINT_FAST8_g;
 
-#define H5T_NATIVE_INT16		(H5open(), H5T_NATIVE_INT16_g)
-#define H5T_NATIVE_UINT16		(H5open(), H5T_NATIVE_UINT16_g)
-#define H5T_NATIVE_INT_LEAST16		(H5open(), H5T_NATIVE_INT_LEAST16_g)
-#define H5T_NATIVE_UINT_LEAST16		(H5open(), H5T_NATIVE_UINT_LEAST16_g)
-#define H5T_NATIVE_INT_FAST16		(H5open(), H5T_NATIVE_INT_FAST16_g)
-#define H5T_NATIVE_UINT_FAST16		(H5open(), H5T_NATIVE_UINT_FAST16_g)
+#define H5T_NATIVE_INT16		(H5OPEN H5T_NATIVE_INT16_g)
+#define H5T_NATIVE_UINT16		(H5OPEN H5T_NATIVE_UINT16_g)
+#define H5T_NATIVE_INT_LEAST16		(H5OPEN H5T_NATIVE_INT_LEAST16_g)
+#define H5T_NATIVE_UINT_LEAST16		(H5OPEN H5T_NATIVE_UINT_LEAST16_g)
+#define H5T_NATIVE_INT_FAST16		(H5OPEN H5T_NATIVE_INT_FAST16_g)
+#define H5T_NATIVE_UINT_FAST16		(H5OPEN H5T_NATIVE_UINT_FAST16_g)
 H5_DLLVAR hid_t H5T_NATIVE_INT16_g;
 H5_DLLVAR hid_t H5T_NATIVE_UINT16_g;
 H5_DLLVAR hid_t H5T_NATIVE_INT_LEAST16_g;
@@ -431,12 +439,12 @@ H5_DLLVAR hid_t H5T_NATIVE_UINT_LEAST16_g;
 H5_DLLVAR hid_t H5T_NATIVE_INT_FAST16_g;
 H5_DLLVAR hid_t H5T_NATIVE_UINT_FAST16_g;
 
-#define H5T_NATIVE_INT32		(H5open(), H5T_NATIVE_INT32_g)
-#define H5T_NATIVE_UINT32		(H5open(), H5T_NATIVE_UINT32_g)
-#define H5T_NATIVE_INT_LEAST32		(H5open(), H5T_NATIVE_INT_LEAST32_g)
-#define H5T_NATIVE_UINT_LEAST32		(H5open(), H5T_NATIVE_UINT_LEAST32_g)
-#define H5T_NATIVE_INT_FAST32		(H5open(), H5T_NATIVE_INT_FAST32_g)
-#define H5T_NATIVE_UINT_FAST32		(H5open(), H5T_NATIVE_UINT_FAST32_g)
+#define H5T_NATIVE_INT32		(H5OPEN H5T_NATIVE_INT32_g)
+#define H5T_NATIVE_UINT32		(H5OPEN H5T_NATIVE_UINT32_g)
+#define H5T_NATIVE_INT_LEAST32		(H5OPEN H5T_NATIVE_INT_LEAST32_g)
+#define H5T_NATIVE_UINT_LEAST32		(H5OPEN H5T_NATIVE_UINT_LEAST32_g)
+#define H5T_NATIVE_INT_FAST32		(H5OPEN H5T_NATIVE_INT_FAST32_g)
+#define H5T_NATIVE_UINT_FAST32		(H5OPEN H5T_NATIVE_UINT_FAST32_g)
 H5_DLLVAR hid_t H5T_NATIVE_INT32_g;
 H5_DLLVAR hid_t H5T_NATIVE_UINT32_g;
 H5_DLLVAR hid_t H5T_NATIVE_INT_LEAST32_g;
@@ -444,12 +452,12 @@ H5_DLLVAR hid_t H5T_NATIVE_UINT_LEAST32_g;
 H5_DLLVAR hid_t H5T_NATIVE_INT_FAST32_g;
 H5_DLLVAR hid_t H5T_NATIVE_UINT_FAST32_g;
 
-#define H5T_NATIVE_INT64		(H5open(), H5T_NATIVE_INT64_g)
-#define H5T_NATIVE_UINT64		(H5open(), H5T_NATIVE_UINT64_g)
-#define H5T_NATIVE_INT_LEAST64		(H5open(), H5T_NATIVE_INT_LEAST64_g)
-#define H5T_NATIVE_UINT_LEAST64 	(H5open(), H5T_NATIVE_UINT_LEAST64_g)
-#define H5T_NATIVE_INT_FAST64		(H5open(), H5T_NATIVE_INT_FAST64_g)
-#define H5T_NATIVE_UINT_FAST64		(H5open(), H5T_NATIVE_UINT_FAST64_g)
+#define H5T_NATIVE_INT64		(H5OPEN H5T_NATIVE_INT64_g)
+#define H5T_NATIVE_UINT64		(H5OPEN H5T_NATIVE_UINT64_g)
+#define H5T_NATIVE_INT_LEAST64		(H5OPEN H5T_NATIVE_INT_LEAST64_g)
+#define H5T_NATIVE_UINT_LEAST64 	(H5OPEN H5T_NATIVE_UINT_LEAST64_g)
+#define H5T_NATIVE_INT_FAST64		(H5OPEN H5T_NATIVE_INT_FAST64_g)
+#define H5T_NATIVE_UINT_FAST64		(H5OPEN H5T_NATIVE_UINT_FAST64_g)
 H5_DLLVAR hid_t H5T_NATIVE_INT64_g;
 H5_DLLVAR hid_t H5T_NATIVE_UINT64_g;
 H5_DLLVAR hid_t H5T_NATIVE_INT_LEAST64_g;
diff --git a/src/H5Tvlen.c b/src/H5Tvlen.c
index b8a4a25..145fc3b 100644
--- a/src/H5Tvlen.c
+++ b/src/H5Tvlen.c
@@ -232,10 +232,6 @@ H5T_vlen_seq_mem_write(hid_t plist_id, H5F_t UNUSED *f, void *vl_addr, void *buf
 
         /* Use the user's memory allocation routine is one is defined */
 
-        /* Get the default dataset transfer property list if the user didn't provide one */
-        if (H5P_DEFAULT == plist_id)
-            plist_id= H5P_DATASET_XFER_DEFAULT;
-
         /* Get the allocation function & info */
         if(NULL == (plist = H5P_object_verify(plist_id,H5P_DATASET_XFER)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list");
@@ -367,10 +363,6 @@ H5T_vlen_str_mem_write(hid_t plist_id, H5F_t UNUSED *f, void *vl_addr, void *buf
 
     /* Use the user's memory allocation routine if one is defined */
 
-    /* Get the default dataset transfer property list if the user didn't provide one */
-    if (H5P_DEFAULT == plist_id)
-        plist_id= H5P_DATASET_XFER_DEFAULT;
-
     /* Get the allocation function & info */
     if(NULL == (plist = H5P_object_verify(plist_id,H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list");
@@ -706,10 +698,6 @@ H5T_vlen_reclaim(void *elem, hid_t type_id, hsize_t UNUSED ndim, hssize_t UNUSED
     if (NULL==(dt=H5I_object_verify(type_id,H5I_DATATYPE)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a data type");
 
-    /* Get the default dataset transfer property list if the user didn't provide one */
-    if (H5P_DEFAULT == plist_id)
-        plist_id= H5P_DATASET_XFER_DEFAULT;
-
     /* Get the free func & information */
     if(NULL == (plist = H5P_object_verify(plist_id,H5P_DATASET_XFER)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a dataset transfer property list");
diff --git a/src/H5detect.c b/src/H5detect.c
index 0d19208..39ee57b 100644
--- a/src/H5detect.c
+++ b/src/H5detect.c
@@ -495,7 +495,7 @@ H5TN_init_interface(void)\n\
 
 	/* The part common to fixed and floating types */
 	printf("\
-    if (NULL==(dt = H5FL_ALLOC (H5T_t,1)))\n\
+    if (NULL==(dt = H5FL_CALLOC (H5T_t)))\n\
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL,\"memory allocation failed\");\n\
     dt->state = H5T_STATE_IMMUTABLE;\n\
     dt->ent.header = HADDR_UNDEF;\n\
diff --git a/src/Makefile.in b/src/Makefile.in
index 1d4f82f..76b7152 100644
--- a/src/Makefile.in
+++ b/src/Makefile.in
@@ -32,13 +32,14 @@ LIB_SRC=H5.c H5A.c H5AC.c H5B.c H5D.c H5E.c H5F.c H5Farray.c H5Fcontig.c      \
         H5Fcompact.c H5Fistore.c H5Fseq.c H5FD.c H5FDcore.c H5FDfamily.c      \
         H5FDgass.c H5FDlog.c H5FDmpio.c H5FDmpiposix.c H5FDmulti.c H5FDsec2.c \
         H5FDsrb.c H5FDstdio.c H5FDstream.c H5FL.c H5FP.c H5FPclient.c         \
-        H5FPserver.c H5G.c H5Gent.c H5Gnode.c H5Gstab.c H5HG.c H5HL.c H5I.c   \
-        H5MF.c H5MM.c H5O.c H5Oattr.c H5Ocomp.c H5Ocont.c H5Odtype.c H5Oefl.c \
+        H5FO.c H5FPserver.c H5G.c H5Gent.c H5Gnode.c H5Gstab.c H5HG.c H5HL.c  \
+        H5I.c H5MF.c H5MM.c H5O.c H5Oattr.c H5Ocont.c H5Odtype.c H5Oefl.c     \
         H5Ofill.c H5Ofphdf5.c H5Olayout.c H5Omtime.c H5Oname.c H5Onull.c      \
-        H5Oplist.c H5Osdspace.c H5Oshared.c H5Ostab.c H5P.c H5Pdcpl.c         \
-        H5Pdxpl.c H5Pfapl.c H5Pfcpl.c H5R.c H5S.c H5Sall.c H5Shyper.c         \
-        H5Smpio.c H5Snone.c H5Spoint.c H5Sselect.c H5T.c H5Tbit.c H5Tconv.c   \
-        H5Tinit.c H5Tvlen.c H5TB.c H5TS.c H5V.c H5Z.c H5Zdeflate.c H5Zshuffle.c
+        H5Opline.c H5Oplist.c H5Osdspace.c H5Oshared.c H5Ostab.c H5P.c        \
+        H5Pdcpl.c H5Pdxpl.c H5Pfapl.c H5Pfcpl.c H5R.c H5RS.c H5S.c H5Sall.c   \
+        H5Shyper.c H5Smpio.c H5Snone.c H5Spoint.c H5Sselect.c H5ST.c H5T.c    \
+        H5Tbit.c H5Tconv.c H5Tinit.c H5Tvlen.c H5TB.c H5TS.c H5V.c H5Z.c      \
+        H5Zdeflate.c H5Zshuffle.c
 
 LIB_OBJ=$(LIB_SRC:.c=.lo)
 
@@ -47,7 +48,7 @@ MOSTLYCLEAN=H5detect.o H5detect.lo H5detect H5Tinit.o H5Tinit.lo H5Tinit.c
 
 ## Public header files (to be installed)...
 PUB_HDR=H5public.h H5Apublic.h H5ACpublic.h H5Bpublic.h H5Dpublic.h           \
-        H5Epublic.h	H5Fpublic.h H5FDpublic.h H5FDcore.h H5FDfamily.h          \
+        H5Epublic.h H5Fpublic.h H5FDpublic.h H5FDcore.h H5FDfamily.h          \
         H5FDgass.h H5FDlog.h H5FDmpio.h H5FDmpiposix.h H5FDmulti.h H5FDsec2.h \
         H5FDsrb.h H5FDstdio.h H5FDstream.h H5FPpublic.h H5Gpublic.h           \
         H5HGpublic.h H5HLpublic.h H5Ipublic.h H5MMpublic.h H5Opublic.h        \
@@ -57,11 +58,12 @@ PUB_HDR=H5public.h H5Apublic.h H5ACpublic.h H5Bpublic.h H5Dpublic.h           \
 ## Other header files (not to be installed)...
 PRIVATE_HDR=H5private.h H5Aprivate.h H5Apkg.h H5ACprivate.h H5Bprivate.h      \
             H5Dprivate.h H5Eprivate.h H5Fprivate.h H5FDprivate.h              \
-            H5FLprivate.h H5FPprivate.h H5Gprivate.h H5Gpkg.h H5HGprivate.h   \
-            H5HLprivate.h H5Iprivate.h H5MFprivate.h H5MMprivate.h            \
-            H5Oprivate.h H5Pprivate.h H5Ppkg.h H5Rprivate.h H5Sprivate.h      \
-            H5Tprivate.h H5TBprivate.h H5Tpkg.h H5TSprivate.h H5Vprivate.h    \
-            H5Zprivate.h H5config.h
+            H5FLprivate.h H5FOprivate.h H5FPprivate.h H5Gprivate.h H5Gpkg.h   \
+            H5HGprivate.h H5HLprivate.h H5Iprivate.h H5MFprivate.h            \
+            H5MMprivate.h H5Oprivate.h H5Pprivate.h H5Ppkg.h H5Rprivate.h     \
+            H5RSprivate.h H5Sprivate.h H5STprivate.h H5Tprivate.h             \
+            H5TBprivate.h H5Tpkg.h H5TSprivate.h H5Vprivate.h H5Zprivate.h    \
+            H5config.h
 
 ## Number format detection
 ## The LD_LIBRARY_PATH setting is a klutch.