[svn-r13155] Description:

    Add "set_crt_index" and "get_crt_index" methods for the object header
message class.

    Unify fractal heap definitions for shared messages and attributes, under
"object header" fractal heap definitions.

    Initial code for adding creation order index to object header messages.

Tested on:
    Linux/32 2.6 (chicago)
    Linux/64 2.6 (chicago2)

36 files changed, 512 insertions, 386 deletions

diff --git a/src/H5A.c b/src/H5A.c
index e4300d5..9e25d02 100644
--- a/src/H5A.c
+++ b/src/H5A.c
@@ -427,7 +427,7 @@ H5A_create(const H5G_loc_t *loc, const char *name, const H5T_t *type,
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, FAIL, "unable to open")
     attr->obj_opened = TRUE;
 
-    /* Create the attribute on the object */
+    /* Insert the attribute into the object header */
     if(H5O_attr_create(&(attr->oloc), dxpl_id, attr) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTINSERT, FAIL, "unable to create attribute in object header")
 
diff --git a/src/H5Abtree2.c b/src/H5Abtree2.c
index 5fb37fe..14d7bb9 100644
--- a/src/H5Abtree2.c
+++ b/src/H5Abtree2.c
@@ -193,7 +193,7 @@ H5A_dense_btree2_name_store(void *_nrecord, const void *_udata)
     /* Copy user information info native record */
     nrecord->hash = udata->common.name_hash;
     nrecord->flags = udata->common.flags;
-    HDmemcpy(nrecord->id, udata->id, (size_t)H5A_DENSE_FHEAP_ID_LEN);
+    nrecord->id = udata->id;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* H5A_dense_btree2_name_store() */
@@ -283,7 +283,7 @@ H5A_dense_btree2_name_compare(const void *_bt2_udata, const void *_bt2_rec)
         HDassert(fheap);
 
         /* Check if the user's link and the B-tree's link have the same name */
-        status = H5HF_op(fheap, bt2_udata->dxpl_id, bt2_rec->id, H5A_dense_fh_name_cmp, &fh_udata);
+        status = H5HF_op(fheap, bt2_udata->dxpl_id, &bt2_rec->id, H5A_dense_fh_name_cmp, &fh_udata);
         HDassert(status >= 0);
 
         /* Callback will set comparison value */
@@ -318,7 +318,7 @@ H5A_dense_btree2_name_encode(const H5F_t UNUSED *f, uint8_t *raw, const void *_n
     /* Encode the record's fields */
     UINT32ENCODE(raw, nrecord->hash)
     *raw++ = nrecord->flags;
-    HDmemcpy(raw, nrecord->id, (size_t)H5A_DENSE_FHEAP_ID_LEN);
+    UINT64ENCODE(raw, nrecord->id);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* H5A_dense_btree2_name_encode() */
@@ -347,7 +347,7 @@ H5A_dense_btree2_name_decode(const H5F_t UNUSED *f, const uint8_t *raw, void *_n
     /* Decode the record's fields */
     UINT32DECODE(raw, nrecord->hash)
     nrecord->flags = *raw++;
-    HDmemcpy(nrecord->id, raw, (size_t)H5A_DENSE_FHEAP_ID_LEN);
+    UINT64DECODE(raw, nrecord->id);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* H5A_dense_btree2_name_decode() */
@@ -371,15 +371,11 @@ H5A_dense_btree2_name_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dx
     int indent, int fwidth, const void *_nrecord, const void UNUSED *_udata)
 {
     const H5A_dense_bt2_name_rec_t *nrecord = (const H5A_dense_bt2_name_rec_t *)_nrecord;
-    unsigned u;                 /* Local index variable */
 
     FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5A_dense_btree2_name_debug)
 
-    HDfprintf(stream, "%*s%-*s {%lx, ", indent, "", fwidth, "Record:",
-        nrecord->hash);
-    for(u = 0; u < H5A_DENSE_FHEAP_ID_LEN; u++)
-        HDfprintf(stderr, "%02x%s", nrecord->id[u], (u < (H5A_DENSE_FHEAP_ID_LEN - 1) ? " " : ", "));
-    HDfprintf(stderr, "%02x}\n", nrecord->flags);
+    HDfprintf(stream, "%*s%-*s {%lx, %Hx, %02x}", indent, "", fwidth, "Record:",
+        nrecord->hash, nrecord->id, nrecord->flags);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* H5A_dense_btree2_name_debug() */
diff --git a/src/H5Adense.c b/src/H5Adense.c
index 1259975..b58a192 100644
--- a/src/H5Adense.c
+++ b/src/H5Adense.c
@@ -47,20 +47,6 @@
 /* Local Macros */
 /****************/
 
-/* Fractal heap creation parameters for "dense" attribute storage */
-/* (Note that these parameters have been tuned so that the resulting heap ID
- *      is exactly 8 bytes.  This is an efficient size and is also the same as
- *      the size of the shared message heap IDs, think carefully before
- *      changing it. -QAK)
- */
-#define H5A_FHEAP_MAN_WIDTH                     4
-#define H5A_FHEAP_MAN_START_BLOCK_SIZE          512
-#define H5A_FHEAP_MAN_MAX_DIRECT_SIZE           (64 * 1024)
-#define H5A_FHEAP_MAN_MAX_INDEX                 40
-#define H5A_FHEAP_MAN_START_ROOT_ROWS           1
-#define H5A_FHEAP_CHECKSUM_DBLOCKS              TRUE
-#define H5A_FHEAP_MAX_MAN_SIZE                  (4 * 1024)
-
 /* v2 B-tree creation macros for 'name' field index */
 #define H5A_NAME_BT2_NODE_SIZE          512
 #define H5A_NAME_BT2_MERGE_PERC         40
@@ -177,7 +163,6 @@ H5A_dense_create(H5F_t *f, hid_t dxpl_id, H5O_t *oh)
 {
     H5HF_create_t fheap_cparam;         /* Fractal heap creation parameters */
     H5HF_t *fheap;                      /* Fractal heap handle */
-    size_t fheap_id_len;                /* Fractal heap ID length */
     size_t bt2_rrec_size;               /* v2 B-tree raw record size */
     herr_t ret_value = SUCCEED;         /* Return value */
 
@@ -192,13 +177,13 @@ H5A_dense_create(H5F_t *f, hid_t dxpl_id, H5O_t *oh)
     /* Set fractal heap creation parameters */
 /* XXX: Give some control of these to applications? */
     HDmemset(&fheap_cparam, 0, sizeof(fheap_cparam));
-    fheap_cparam.managed.width = H5A_FHEAP_MAN_WIDTH;
-    fheap_cparam.managed.start_block_size = H5A_FHEAP_MAN_START_BLOCK_SIZE;
-    fheap_cparam.managed.max_direct_size = H5A_FHEAP_MAN_MAX_DIRECT_SIZE;
-    fheap_cparam.managed.max_index = H5A_FHEAP_MAN_MAX_INDEX;
-    fheap_cparam.managed.start_root_rows = H5A_FHEAP_MAN_START_ROOT_ROWS;
-    fheap_cparam.checksum_dblocks = H5A_FHEAP_CHECKSUM_DBLOCKS;
-    fheap_cparam.max_man_size = H5A_FHEAP_MAX_MAN_SIZE;
+    fheap_cparam.managed.width = H5O_FHEAP_MAN_WIDTH;
+    fheap_cparam.managed.start_block_size = H5O_FHEAP_MAN_START_BLOCK_SIZE;
+    fheap_cparam.managed.max_direct_size = H5O_FHEAP_MAN_MAX_DIRECT_SIZE;
+    fheap_cparam.managed.max_index = H5O_FHEAP_MAN_MAX_INDEX;
+    fheap_cparam.managed.start_root_rows = H5O_FHEAP_MAN_START_ROOT_ROWS;
+    fheap_cparam.checksum_dblocks = H5O_FHEAP_CHECKSUM_DBLOCKS;
+    fheap_cparam.max_man_size = H5O_FHEAP_MAX_MAN_SIZE;
 
     /* Create fractal heap for storing attributes */
     if(NULL == (fheap = H5HF_create(f, dxpl_id, &fheap_cparam)))
@@ -211,14 +196,19 @@ H5A_dense_create(H5F_t *f, hid_t dxpl_id, H5O_t *oh)
 HDfprintf(stderr, "%s: oh->attr_fheap_addr = %a\n", FUNC, oh->attr_fheap_addr);
 #endif /* QAK */
 
+#ifndef NDEBUG
+{
+    size_t fheap_id_len;                /* Fractal heap ID length */
+
     /* Retrieve the heap's ID length in the file */
     if(H5HF_get_id_len(fheap, &fheap_id_len) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTGETSIZE, FAIL, "can't get fractal heap ID length")
-    HDassert(fheap_id_len == H5A_DENSE_FHEAP_ID_LEN);
-    HDassert(fheap_id_len == H5SM_FHEAP_ID_LEN);        /* Need to be interchangable -QAK */
+    HDassert(fheap_id_len == H5O_FHEAP_ID_LEN);
 #ifdef QAK
 HDfprintf(stderr, "%s: fheap_id_len = %Zu\n", FUNC, fheap_id_len);
 #endif /* QAK */
+}
+#endif /* NDEBUG */
 
     /* Close the fractal heap */
     if(H5HF_close(fheap, dxpl_id) < 0)
@@ -227,7 +217,7 @@ HDfprintf(stderr, "%s: fheap_id_len = %Zu\n", FUNC, fheap_id_len);
     /* Create the name index v2 B-tree */
     bt2_rrec_size = 4 +                 /* Name's hash value */
             1 +                         /* Message flags */
-            fheap_id_len;               /* Fractal heap ID */
+            H5O_FHEAP_ID_LEN;           /* Fractal heap ID */
     if(H5B2_create(f, dxpl_id, H5A_BT2_NAME,
             (size_t)H5A_NAME_BT2_NODE_SIZE, bt2_rrec_size,
             H5A_NAME_BT2_SPLIT_PERC, H5A_NAME_BT2_MERGE_PERC,
@@ -243,7 +233,7 @@ HDfprintf(stderr, "%s: oh->name_bt2_addr = %a\n", FUNC, oh->name_bt2_addr);
     if(linfo->index_corder) {
         /* Create the creation order index v2 B-tree */
         bt2_rrec_size = 8 +             /* Creation order value */
-                fheap_id_len;           /* Fractal heap ID */
+                H5O_FHEAP_ID_LEN;       /* Fractal heap ID */
         if(H5B2_create(f, dxpl_id, H5A_BT2_CORDER,
                 (size_t)H5A_CORDER_BT2_NODE_SIZE, bt2_rrec_size,
                 H5A_CORDER_BT2_SPLIT_PERC, H5A_CORDER_BT2_MERGE_PERC,
@@ -398,7 +388,6 @@ H5A_dense_insert(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, unsigned mesg_flags,
     H5A_bt2_ud_ins_t udata;             /* User data for v2 B-tree insertion */
     H5HF_t *fheap = NULL;               /* Fractal heap handle for attributes */
     H5HF_t *shared_fheap = NULL;        /* Fractal heap handle for shared header messages */
-    uint8_t id[H5A_DENSE_FHEAP_ID_LEN]; /* Heap ID of attribute to insert    */
     H5O_shared_t sh_mesg;               /* Shared object header message */
     uint8_t attr_buf[H5A_ATTR_BUF_SIZE]; /* Buffer for serializing message */
     void *attr_ptr = NULL;              /* Pointer to serialized message */
@@ -447,7 +436,7 @@ H5A_dense_insert(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, unsigned mesg_flags,
             HGOTO_ERROR(H5E_ATTR, H5E_BADMESG, FAIL, "can't get shared message")
 
         /* Use heap ID for shared message heap */
-        udata.id = (const uint8_t *)&sh_mesg.u.heap_id;
+        udata.id = sh_mesg.u.heap_id;
     } /* end if */
     else {
         size_t attr_size;                   /* Size of serialized attribute in the heap */
@@ -469,11 +458,9 @@ H5A_dense_insert(H5F_t *f, hid_t dxpl_id, const H5O_t *oh, unsigned mesg_flags,
             HGOTO_ERROR(H5E_ATTR, H5E_CANTENCODE, FAIL, "can't encode attribute")
 
         /* Insert the serialized attribute into the fractal heap */
-        if(H5HF_insert(fheap, dxpl_id, attr_size, attr_ptr, id) < 0)
+        /* (sets the heap ID in the user data) */
+        if(H5HF_insert(fheap, dxpl_id, attr_size, attr_ptr, &udata.id) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTINSERT, FAIL, "unable to insert attribute into fractal heap")
-
-        /* Use heap ID for attribute heap */
-        udata.id = id;
     } /* end else */
 
     /* Create the callback information for v2 B-tree record insertion */
@@ -553,7 +540,7 @@ H5A_dense_write_bt2_cb(void *_record, void *_op_data, hbool_t *changed)
             HGOTO_ERROR(H5E_ATTR, H5E_BADMESG, FAIL, "can't get shared info")
 
         /* Update record's heap ID */
-        HDmemcpy(record->id, &op_data->attr->sh_loc.u.heap_id, sizeof(record->id));
+        record->id = op_data->attr->sh_loc.u.heap_id;
 
         /* Note that the record changed */
         *changed = TRUE;
@@ -582,14 +569,14 @@ H5A_dense_write_bt2_cb(void *_record, void *_op_data, hbool_t *changed)
 {
     size_t obj_len;             /* Length of existing encoded attribute */
 
-    if(H5HF_get_obj_len(op_data->fheap, op_data->dxpl_id, record->id, &obj_len) < 0)
+    if(H5HF_get_obj_len(op_data->fheap, op_data->dxpl_id, &record->id, &obj_len) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTGETSIZE, FAIL, "can't get object size")
     HDassert(obj_len == attr_size);
 }
 #endif /* NDEBUG */
         /* Update existing attribute in heap */
         /* (would be more efficient as fractal heap 'op' callback, but leave that for later -QAK) */
-        if(H5HF_write(op_data->fheap, op_data->dxpl_id, record->id, changed, attr_ptr) < 0)
+        if(H5HF_write(op_data->fheap, op_data->dxpl_id, &record->id, changed, attr_ptr) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTUPDATE, FAIL, "unable to update attribute in heap")
     } /* end else */
 
@@ -910,8 +897,7 @@ H5A_dense_iterate_bt2_cb(const void *_record, void *_bt2_udata)
         fh_udata.attr = NULL;
 
         /* Call fractal heap 'op' routine, to copy the attribute information */
-        if(H5HF_op(fheap, bt2_udata->dxpl_id, record->id,
-                H5A_dense_copy_fh_cb, &fh_udata) < 0)
+        if(H5HF_op(fheap, bt2_udata->dxpl_id, &record->id, H5A_dense_copy_fh_cb, &fh_udata) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTOPERATE, H5_ITER_ERROR, "heap op callback failed")
 
         /* Check which type of callback to make */
@@ -1098,7 +1084,7 @@ H5A_dense_remove_bt2_cb(const void *_record, void *_bt2_udata)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTDELETE, FAIL, "unable to delete attribute")
 
         /* Remove record from fractal heap */
-        if(H5HF_remove(bt2_udata->fheap, bt2_udata->dxpl_id, record->id) < 0)
+        if(H5HF_remove(bt2_udata->fheap, bt2_udata->dxpl_id, &record->id) < 0)
             HGOTO_ERROR(H5E_ATTR, H5E_CANTREMOVE, FAIL, "unable to remove attribute from fractal heap")
     } /* end else */
 
@@ -1316,7 +1302,7 @@ H5A_dense_delete_bt2_cb(const void *_record, void *_bt2_udata)
     fh_udata.attr = NULL;
 
     /* Call fractal heap 'op' routine, to copy the attribute information */
-    if(H5HF_op(fheap, bt2_udata->dxpl_id, record->id, H5A_dense_copy_fh_cb, &fh_udata) < 0)
+    if(H5HF_op(fheap, bt2_udata->dxpl_id, &record->id, H5A_dense_copy_fh_cb, &fh_udata) < 0)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPERATE, FAIL, "heap op callback failed")
 
     /* Check for shared attribute */
diff --git a/src/H5Apkg.h b/src/H5Apkg.h
index ca4b50d..a3910a9 100644
--- a/src/H5Apkg.h
+++ b/src/H5Apkg.h
@@ -50,9 +50,6 @@
 /* Package Private Macros */
 /**************************/
 
-/* Standard length of fractal heap ID for attribute */
-#define H5A_DENSE_FHEAP_ID_LEN  8
-
 
 /****************************/
 /* Package Private Typedefs */
@@ -73,6 +70,7 @@ struct H5A_t {
     void        *data;      /* Attribute data (on a temporary basis) */
     size_t      data_size;  /* Size of data on disk */
     H5O_shared_t sh_loc;    /* Location of shared message */
+    H5O_crt_idx_t crt_idx;  /* Attribute's creation index in the object header */
 };
 
 /* Typedefs for "dense" attribute storage */
@@ -81,7 +79,7 @@ struct H5A_t {
 /* Typedef for native 'name' field index records in the v2 B-tree */
 /* (Keep 'id' field first so generic record handling in callbacks works) */
 typedef struct H5A_dense_bt2_name_rec_t {
-    uint8_t id[H5A_DENSE_FHEAP_ID_LEN]; /* Heap ID for link */
+    H5O_fheap_id_t id;                  /* Heap ID for attribute */
     uint8_t flags;                      /* Message flags for attribute */
     uint32_t hash;                      /* Hash of 'name' field value */
 } H5A_dense_bt2_name_rec_t;
@@ -112,7 +110,7 @@ typedef struct H5A_bt2_ud_common_t {
 typedef struct H5A_bt2_ud_ins_t {
     /* downward */
     H5A_bt2_ud_common_t common;         /* Common info for B-tree user data (must be first) */
-    const uint8_t *id;                  /* Heap ID of attribute to insert    */
+    H5O_fheap_id_t id;                  /* Heap ID of attribute to insert    */
 } H5A_bt2_ud_ins_t;
 
 /* Data structure to hold table of attributes for an object */
diff --git a/src/H5D.c b/src/H5D.c
index 090b0c3..a0304a6 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -1195,7 +1195,7 @@ H5D_update_entry_info(H5F_t *file, hid_t dxpl_id, H5D_t *dset)
     /* fill value variables */
     H5D_fill_time_t	fill_time;
     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};
+    H5O_fill_new_t      fill;           /* Default fill value */
     H5D_fill_value_t	fill_status;
 
     struct H5O_t       *oh = NULL;      /* Pointer to dataset's object header */
@@ -1208,6 +1208,12 @@ H5D_update_entry_info(H5F_t *file, hid_t dxpl_id, H5D_t *dset)
     HDassert(file);
     HDassert(dset);
 
+    /* Portably initialize the fill value */
+    HDmemset(&fill, 0, sizeof(H5O_fill_new_t));
+    fill.alloc_time = H5D_ALLOC_TIME_LATE;
+    fill.fill_time = H5D_FILL_TIME_ALLOC;
+    fill.fill_defined = TRUE;
+
     /* Set some location variables, for convenience */
     oloc = &dset->oloc;
     layout = &dset->shared->layout;
@@ -1858,7 +1864,7 @@ done:
 static herr_t
 H5D_open_oid(H5D_t *dataset, hid_t dxpl_id)
 {
-    H5O_fill_new_t  fill = {NULL, 0, NULL, H5D_ALLOC_TIME_LATE, H5D_FILL_TIME_IFSET, TRUE};
+    H5O_fill_new_t      fill;           /* Default fill value */
     unsigned    alloc_time_state;       /* Allocation time state */
     H5O_fill_t     *fill_prop;          /* Pointer to dataset's fill value area */
     H5O_pline_t  pline;                 /* I/O pipeline information */
@@ -1870,6 +1876,12 @@ H5D_open_oid(H5D_t *dataset, hid_t dxpl_id)
     /* check args */
     HDassert(dataset);
 
+    /* Portably initialize the fill value */
+    HDmemset(&fill, 0, sizeof(H5O_fill_new_t));
+    fill.alloc_time = H5D_ALLOC_TIME_LATE;
+    fill.fill_time = H5D_FILL_TIME_ALLOC;
+    fill.fill_defined = TRUE;
+
     /* (Set the 'vl_type' parameter to FALSE since it doesn't matter from here) */
     if(NULL == (dataset->shared = H5D_new(H5P_DATASET_CREATE_DEFAULT, FALSE, FALSE)))
         HGOTO_ERROR (H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
diff --git a/src/H5O.c b/src/H5O.c
index 9470a7f..2101fa3 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -30,6 +30,9 @@
 #define H5F_PACKAGE		/*suppress error about including H5Fpkg	  */
 #define H5O_PACKAGE		/*suppress error about including H5Opkg	  */
 
+/* Interface initialization */
+#define H5_INTERFACE_INIT_FUNC	H5O_init_interface
+
 /***********/
 /* Headers */
 /***********/
@@ -64,8 +67,6 @@
 /********************/
 
 static hid_t H5O_open_by_loc(H5G_loc_t *obj_loc, hid_t dxpl_id);
-static herr_t H5O_new(H5F_t *f, hid_t dxpl_id, haddr_t header, size_t chunk_size,
-    hid_t ocpl_id, H5O_loc_t *loc/*out*/);
 static herr_t H5O_delete_oh(H5F_t *f, hid_t dxpl_id, H5O_t *oh);
 static const H5O_obj_class_t *H5O_obj_class(H5O_loc_t *loc, hid_t dxpl_id);
 static herr_t H5O_obj_type_real(H5O_t *oh, H5O_type_t *obj_type);
@@ -142,6 +143,31 @@ H5FL_EXTERN(time_t);
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5O_init_interface
+ *
+ * Purpose:	Initialize information specific to H5O interface.
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	Quincey Koziol
+ *              Thursday, January 18, 2007
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5O_init_interface(void)
+{
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5O_init_interface)
+
+    /* H5O interface sanity checks */
+    HDassert(H5O_MSG_TYPES == NELMTS(H5O_msg_class_g));
+    HDassert(sizeof(H5O_fheap_id_t) == H5O_FHEAP_ID_LEN);
+
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5O_init_interface() */
+
+
+/*-------------------------------------------------------------------------
  * Function:	H5Oopen
  *
  * Purpose:	Opens an object within an HDF5 file.
@@ -620,77 +646,27 @@ herr_t
 H5O_create(H5F_t *f, hid_t dxpl_id, size_t size_hint, hid_t ocpl_id,
     H5O_loc_t *loc/*out*/)
 {
-    haddr_t	header;                 /* Address of object header */
-    herr_t      ret_value = SUCCEED;    /* return value */
-
-    FUNC_ENTER_NOAPI(H5O_create, FAIL)
-
-    /* check args */
-    HDassert(f);
-    HDassert(loc);
-
-    /* Make certain we allocate at least a reasonable size for the object header */
-    size_hint = H5O_ALIGN_F(f, MAX(H5O_MIN_SIZE, size_hint));
-
-    /* allocate disk space for header and first chunk */
-    if(HADDR_UNDEF == (header = H5MF_alloc(f, H5FD_MEM_OHDR, dxpl_id,
-            (hsize_t)H5O_SIZEOF_HDR_F(f) + size_hint)))
-        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "file allocation failed for object header header")
-
-    /* initialize the object header */
-    if(H5O_new(f, dxpl_id, header, size_hint, ocpl_id, loc) != SUCCEED)
-        HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to initialize object header")
-
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5O_create() */
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5O_new
- *
- * Purpose:	Initialize a new object header, sets the link count to 0,
- *              and caches the header. The object header is opened for
- *              write access and should eventually be closed by calling
- *              H5O_close().
- *
- * Return:	Success:    SUCCEED, the LOC argument contains
- *                          information about the object header,
- *                          including its address.
- *		Failure:    FAIL
- *
- * Programmer:	Bill Wendling
- *		1, November 2002
- *
- *-------------------------------------------------------------------------
- */
-static herr_t
-H5O_new(H5F_t *f, hid_t dxpl_id, haddr_t header, size_t chunk_size,
-    hid_t ocpl_id, H5O_loc_t *loc/*out*/)
-{
     H5O_t      *oh = NULL;
+    haddr_t     oh_addr;                /* Address of initial object header */
     size_t      oh_size;                /* Size of initial object header */
     herr_t      ret_value = SUCCEED;    /* return value */
 
-    FUNC_ENTER_NOAPI_NOINIT(H5O_new)
+    FUNC_ENTER_NOAPI(H5O_create, FAIL)
 
     /* check args */
     HDassert(f);
     HDassert(loc);
     HDassert(TRUE == H5P_isa_class(ocpl_id, H5P_OBJECT_CREATE));
 
-    /* Set up object location */
-    loc->file = f;
-    loc->addr = header;
+    /* Make certain we allocate at least a reasonable size for the object header */
+    size_hint = H5O_ALIGN_F(f, MAX(H5O_MIN_SIZE, size_hint));
 
     /* Allocate the object header and fill in header fields */
-    if(NULL == (oh = H5FL_MALLOC(H5O_t)))
+    if(NULL == (oh = H5FL_CALLOC(H5O_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
 
     /* Initialize rudimentary information object object header */
     oh->version = H5F_USE_LATEST_FORMAT(f) ? H5O_VERSION_LATEST : H5O_VERSION_1;
-    oh->nlink = 0;
-    oh->skipped_mesg_size = 0;
     oh->sizeof_size = H5F_SIZEOF_SIZE(f);
     oh->sizeof_addr = H5F_SIZEOF_ADDR(f);
 
@@ -714,7 +690,6 @@ H5O_new(H5F_t *f, hid_t dxpl_id, haddr_t header, size_t chunk_size,
             HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, FAIL, "can't get min. # of dense attributes")
 
         /* Set starting values for attribute info */
-        oh->nattrs = 0;
         oh->attr_fheap_addr = HADDR_UNDEF;
         oh->name_bt2_addr = HADDR_UNDEF;
     } /* end if */
@@ -723,16 +698,17 @@ H5O_new(H5F_t *f, hid_t dxpl_id, haddr_t header, size_t chunk_size,
         oh->atime = oh->mtime = oh->ctime = oh->btime = 0;
 
         /* Reset unused attribute fields */
-        oh->max_compact = 0;
-        oh->min_dense = 0;
-        oh->nattrs = 0;
         oh->attr_fheap_addr = HADDR_UNDEF;
         oh->name_bt2_addr = HADDR_UNDEF;
     } /* end else */
 
     /* Compute total size of initial object header */
     /* (i.e. object header prefix and first chunk) */
-    oh_size = H5O_SIZEOF_HDR_OH(oh) + chunk_size;
+    oh_size = H5O_SIZEOF_HDR(oh) + size_hint;
+
+    /* Allocate disk space for header and first chunk */
+    if(HADDR_UNDEF == (oh_addr = H5MF_alloc(f, H5FD_MEM_OHDR, dxpl_id, (hsize_t)oh_size)))
+        HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "file allocation failed for object header header")
 
     /* Create the chunk list */
     oh->nchunks = oh->alloc_nchunks = 1;
@@ -741,7 +717,7 @@ H5O_new(H5F_t *f, hid_t dxpl_id, haddr_t header, size_t chunk_size,
 
     /* Initialize the first chunk */
     oh->chunk[0].dirty = TRUE;
-    oh->chunk[0].addr = loc->addr;
+    oh->chunk[0].addr = oh_addr;
     oh->chunk[0].size = oh_size;
     oh->chunk[0].gap = 0;
 
@@ -764,26 +740,29 @@ H5O_new(H5F_t *f, hid_t dxpl_id, haddr_t header, size_t chunk_size,
     oh->mesg[0].type = H5O_MSG_NULL;
     oh->mesg[0].dirty = TRUE;
     oh->mesg[0].native = NULL;
-    oh->mesg[0].raw = oh->chunk[0].image + (H5O_SIZEOF_HDR_OH(oh) - H5O_SIZEOF_CHKSUM_OH(oh)) + H5O_SIZEOF_MSGHDR_OH(oh);
-    oh->mesg[0].raw_size = chunk_size - H5O_SIZEOF_MSGHDR_OH(oh);
+    oh->mesg[0].raw = oh->chunk[0].image + (H5O_SIZEOF_HDR(oh) - H5O_SIZEOF_CHKSUM_OH(oh)) + H5O_SIZEOF_MSGHDR_OH(oh);
+    oh->mesg[0].raw_size = size_hint - H5O_SIZEOF_MSGHDR_OH(oh);
     oh->mesg[0].chunkno = 0;
 
     /* Cache object header */
-    if(H5AC_set(f, dxpl_id, H5AC_OHDR, loc->addr, oh, H5AC__NO_FLAGS_SET) < 0)
+    if(H5AC_set(f, dxpl_id, H5AC_OHDR, oh_addr, oh, H5AC__NO_FLAGS_SET) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to cache object header")
 
+    /* Set up object location */
+    loc->file = f;
+    loc->addr = oh_addr;
+
     /* Open it */
     if(H5O_open(loc) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, FAIL, "unable to open object header")
 
 done:
-    if(ret_value < 0 && oh) {
+    if(ret_value < 0 && oh)
         if(H5O_dest(f, oh) < 0)
 	    HDONE_ERROR(H5E_OHDR, H5E_CANTFREE, FAIL, "unable to destroy object header data")
-    } /* end if */
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5O_new() */
+} /* end H5O_create() */
 
 
 /*-------------------------------------------------------------------------
@@ -802,21 +781,24 @@ done:
 herr_t
 H5O_open(const H5O_loc_t *loc)
 {
-    FUNC_ENTER_NOAPI_NOFUNC(H5O_open)
+    herr_t ret_value = SUCCEED;         /* Return value */
+
+    FUNC_ENTER_NOAPI(H5O_open, FAIL)
 
     /* Check args */
     HDassert(loc);
     HDassert(loc->file);
 
 #ifdef H5O_DEBUG
-    if (H5DEBUG(O))
+    if(H5DEBUG(O))
 	HDfprintf(H5DEBUG(O), "> %a\n", loc->addr);
 #endif
 
     /* Increment open-lock counters */
     loc->file->nopen_objs++;
 
-    FUNC_LEAVE_NOAPI(SUCCEED)
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5O_open() */
 
 
@@ -1848,7 +1830,7 @@ H5O_get_info(H5O_loc_t *oloc, H5O_info_t *oinfo, hid_t dxpl_id)
 
     /* Iterate over all the messages, accumulating message size & type information */
     oinfo->num_attrs = 0;
-    oinfo->hdr.meta_space = H5O_SIZEOF_HDR_OH(oh) + (H5O_SIZEOF_CHKHDR_OH(oh) * (oh->nchunks - 1));
+    oinfo->hdr.meta_space = H5O_SIZEOF_HDR(oh) + (H5O_SIZEOF_CHKHDR_OH(oh) * (oh->nchunks - 1));
     oinfo->hdr.mesg_space = 0;
     oinfo->hdr.free_space = 0;
     oinfo->hdr.msg_present = 0;
diff --git a/src/H5Oalloc.c b/src/H5Oalloc.c
index b1a81aa..bb23c2b 100644
--- a/src/H5Oalloc.c
+++ b/src/H5Oalloc.c
@@ -838,12 +838,8 @@ done:
  *-------------------------------------------------------------------------
  */
 unsigned
-H5O_alloc(H5F_t *f,
-          hid_t dxpl_id,
-          H5O_t *oh,
-          const H5O_msg_class_t *type,
-          size_t size,
-          unsigned * oh_flags_ptr)
+H5O_alloc(H5F_t *f, hid_t dxpl_id, H5O_t *oh, const H5O_msg_class_t *type,
+    size_t size, unsigned * oh_flags_ptr)
 {
     size_t      aligned_size = H5O_ALIGN_OH(oh, size);
     unsigned    idx;            /* Index of message which fits allocation */
diff --git a/src/H5Oattr.c b/src/H5Oattr.c
index d70aab0..a2c6654 100644
--- a/src/H5Oattr.c
+++ b/src/H5Oattr.c
@@ -39,6 +39,8 @@ static void *H5O_attr_copy_file(H5F_t *file_src, const H5O_msg_class_t *mesg_typ
     void *native_src, H5F_t *file_dst, hid_t dxpl_id, H5O_copy_t *cpy_info,
     void *udata);
 static herr_t H5O_attr_set_share(void *_mesg, const H5O_shared_t *sh);
+static herr_t H5O_attr_get_crt_index(const void *_mesg, H5O_crt_idx_t *crt_idx);
+static herr_t H5O_attr_set_crt_index(void *_mesg, H5O_crt_idx_t crt_idx);
 static herr_t H5O_attr_debug(H5F_t *f, hid_t dxpl_id, const void *_mesg,
 			      FILE * stream, int indent, int fwidth);
 
@@ -62,6 +64,8 @@ const H5O_msg_class_t H5O_MSG_ATTR[1] = {{
     H5O_attr_pre_copy_file,	/* pre copy native value to file */
     H5O_attr_copy_file,		/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL /* H5O_attr_get_crt_index */,	/* get creation index		*/
+    NULL /* H5O_attr_set_crt_index */,	/* set creation index		*/
     H5O_attr_debug		/* debug the message            */
 }};
 
@@ -741,6 +745,96 @@ done:
 
 
 /*-------------------------------------------------------------------------
+ * Function:	H5O_attr_get_share
+ *
+ * Purpose:	Gets sharing information from the message
+ *
+ * Return:	Shared message on success/NULL on failure
+ *
+ * Programmer:	James Laird
+ *              Tuesday, October 17, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+void *
+H5O_attr_get_share(const void *_mesg, H5O_shared_t *sh /*out*/)
+{
+    const H5A_t  *mesg = (const H5A_t *)_mesg;
+    void         *ret_value = NULL;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5O_attr_get_share)
+
+    HDassert(mesg);
+
+    ret_value = H5O_msg_copy(H5O_SHARED_ID, &(mesg->sh_loc), sh);
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5O_attr_get_share() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5O_attr_set_share
+ *
+ * Purpose:	Sets sharing information for the message
+ *
+ * Return:	Non-negative on success/Negative on failure
+ *
+ * Programmer:	James Laird
+ *              Tuesday, October 10, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+static herr_t
+H5O_attr_set_share(void *_mesg/*in,out*/, const H5O_shared_t *sh)
+{
+    H5A_t  *mesg = (H5A_t *)_mesg;
+    herr_t       ret_value = SUCCEED;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5O_attr_set_share)
+
+    HDassert(mesg);
+    HDassert(sh);
+
+    if(NULL == H5O_msg_copy(H5O_SHARED_ID, sh, &(mesg->sh_loc)))
+        ret_value = FAIL;
+
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5O_attr_set_share() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5O_attr_is_shared
+ *
+ * Purpose:	Determines if this attribute is shared (committed or a SOHM)
+ *              or not.
+ *
+ * Return:	TRUE if attribute is shared
+ *              FALSE if attribute is not shared
+ *              Negative on failure
+ *
+ * Programmer:	James Laird
+ *		Tuesday, October 17, 2006
+ *
+ *-------------------------------------------------------------------------
+ */
+htri_t
+H5O_attr_is_shared(const void *_mesg)
+{
+    const H5A_t  *mesg = (const H5A_t *)_mesg;
+
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5O_attr_is_shared)
+
+    HDassert(mesg);
+
+    /* Attributes can't currently be committed, but this should let the
+     * library read a "committed attribute" if we ever create one in
+     * the future.
+     */
+    FUNC_LEAVE_NOAPI(H5O_IS_SHARED(mesg->sh_loc.flags))
+} /* end H5O_attr_is_shared */
+
+
+/*-------------------------------------------------------------------------
  * Function:    H5O_attr_pre_copy_file
  *
  * Purpose:     Perform any necessary actions before copying message between
@@ -914,9 +1008,8 @@ H5O_attr_copy_file(H5F_t *file_src, const H5O_msg_class_t UNUSED *mesg_type,
         /* Compute shared message size for dataspace */
         attr_dst->ds_size = H5O_msg_raw_size(file_dst, H5O_SHARED_ID, &sh_mesg);
     }
-    else {
+    else
         attr_dst->ds_size = H5O_msg_raw_size(file_dst, H5O_SDSPACE_ID, attr_src->ds);
-    }
     HDassert(attr_dst->ds_size > 0);
 
     /* Compute the size of the data */
@@ -1077,93 +1170,62 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5O_attr_get_share
+ * Function:	H5O_attr_get_crt_index
  *
- * Purpose:	Gets sharing information from the message
+ * Purpose:	Get creation index from the message
  *
- * Return:	Shared message on success/NULL on failure
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
  *
- * Programmer:	James Laird
- *              Tuesday, October 17, 2006
+ * Programmer:	Quincey Koziol
+ *              Thursday, January 18, 2007
  *
  *-------------------------------------------------------------------------
  */
-void *
-H5O_attr_get_share(const void *_mesg, H5O_shared_t *sh /*out*/)
+herr_t
+H5O_attr_get_crt_index(const void *_mesg, H5O_crt_idx_t *crt_idx /*out*/)
 {
-    const H5A_t  *mesg = (const H5A_t *)_mesg;
-    void         *ret_value = NULL;
+    const H5A_t  *attr = (const H5A_t *)_mesg;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5O_attr_get_share)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5O_attr_get_crt_index)
 
-    HDassert(mesg);
+    HDassert(attr);
+    HDassert(crt_idx);
 
-    ret_value = H5O_msg_copy(H5O_SHARED_ID, &(mesg->sh_loc), sh);
+    /* Get the attribute's creation index */
+    *crt_idx = attr->crt_idx;
 
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5O_attr_get_share() */
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5O_attr_get_crt_index() */
 
 
 /*-------------------------------------------------------------------------
- * Function:	H5O_attr_set_share
+ * Function:	H5O_attr_set_crt_index
  *
- * Purpose:	Sets sharing information for the message
+ * Purpose:	Set creation index from the message
  *
- * Return:	Non-negative on success/Negative on failure
+ * Return:      Success:        Non-negative
+ *              Failure:        Negative
  *
- * Programmer:	James Laird
- *              Tuesday, October 10, 2006
+ * Programmer:	Quincey Koziol
+ *              Thursday, January 18, 2007
  *
  *-------------------------------------------------------------------------
  */
-static herr_t
-H5O_attr_set_share(void *_mesg/*in,out*/, const H5O_shared_t *sh)
+herr_t
+H5O_attr_set_crt_index(void *_mesg, H5O_crt_idx_t crt_idx)
 {
-    H5A_t  *mesg = (H5A_t *)_mesg;
-    herr_t       ret_value = SUCCEED;
+    H5A_t  *attr = (H5A_t *)_mesg;
 
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5O_attr_set_share)
-
-    HDassert(mesg);
-    HDassert(sh);
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5O_attr_set_crt_index)
 
-    if(NULL == H5O_msg_copy(H5O_SHARED_ID, sh, &(mesg->sh_loc)))
-        ret_value = FAIL;
-
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5O_attr_set_share() */
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5O_attr_is_shared
- *
- * Purpose:	Determines if this attribute is shared (committed or a SOHM)
- *              or not.
- *
- * Return:	TRUE if attribute is shared
- *              FALSE if attribute is not shared
- *              Negative on failure
- *
- * Programmer:	James Laird
- *		Tuesday, October 17, 2006
- *
- *-------------------------------------------------------------------------
- */
-htri_t
-H5O_attr_is_shared(const void *_mesg)
-{
-    const H5A_t  *mesg = (const H5A_t *)_mesg;
-
-    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5O_attr_is_shared)
+    HDassert(attr);
 
-    HDassert(mesg);
+    /* Set the creation index */
+    attr->crt_idx = crt_idx;
 
-    /* Attributes can't currently be committed, but this should let the
-     * library read a "committed attribute" if we ever create one in
-     * the future.
-     */
-    FUNC_LEAVE_NOAPI(H5O_IS_SHARED(mesg->sh_loc.flags))
-} /* end H5O_attr_is_shared */
+    FUNC_LEAVE_NOAPI(SUCCEED)
+} /* end H5O_attr_set_crt_index() */
 
 
 /*--------------------------------------------------------------------------
diff --git a/src/H5Oattribute.c b/src/H5Oattribute.c
index 6cc3c02..defc7ba 100644
--- a/src/H5Oattribute.c
+++ b/src/H5Oattribute.c
@@ -311,6 +311,16 @@ HDfprintf(stderr, "%s: converting attributes to dense storage\n", FUNC);
     /* Increment attribute count */
     oh->nattrs++;
 
+    /* Check if the object is tracking creation order on attributes */
+    if(oh->flags & H5P_CRT_ORDER_TRACKED) {
+        /* Check for attribute creation order index on the object wrapping around */
+        if(oh->max_attr_crt_idx == H5O_MAX_CRT_ORDER_IDX)
+            HGOTO_ERROR(H5E_ATTR, H5E_CANTINC, FAIL, "Attribute creation index can't be incremented")
+
+        /* Set the creation order index on the attribute & incr. creation order index */
+        attr->crt_idx = oh->max_attr_crt_idx++;
+    } /* end if */
+
     /* Check for storing attribute with dense storage */
     if(H5F_addr_defined(oh->attr_fheap_addr)) {
         /* Insert attribute into dense storage */
diff --git a/src/H5Obogus.c b/src/H5Obogus.c
index 21a983e..627977e 100644
--- a/src/H5Obogus.c
+++ b/src/H5Obogus.c
@@ -63,6 +63,8 @@ const H5O_msg_class_t H5O_MSG_BOGUS[1] = {{
     NULL,			/* pre copy native value to file */
     NULL,			/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_bogus_debug         	/*debug the message             */
 }};
 
diff --git a/src/H5Ocache.c b/src/H5Ocache.c
index 74083e4..dd09c0a 100644
--- a/src/H5Ocache.c
+++ b/src/H5Ocache.c
@@ -142,6 +142,10 @@ H5O_flush_msgs(H5F_t *f, H5O_t *oh)
                 *p++ = 0; /*reserved*/
                 *p++ = 0; /*reserved*/
             } /* end for */
+            /* Only encode creation index for version 2+ of format */
+            else {
+                UINT16ENCODE(p, curr_msg->crt_idx);
+            } /* end else */
             HDassert(p == curr_msg->raw);
 
 #ifndef NDEBUG
@@ -273,6 +277,9 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
         oh->version = *p++;
         if(H5O_VERSION_2 != oh->version)
             HGOTO_ERROR(H5E_OHDR, H5E_VERSION, NULL, "bad object header version number")
+
+        /* Flags */
+        oh->flags = *p++;
     } /* end if */
     else {
         /* Version */
@@ -304,6 +311,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
         H5F_DECODE_LENGTH(f, p, oh->nattrs);
         H5F_addr_decode(f, &p, &(oh->attr_fheap_addr));
         H5F_addr_decode(f, &p, &(oh->name_bt2_addr));
+        UINT16DECODE(p, oh->max_attr_crt_idx);
     } /* end if */
     else {
         /* Reset unused time fields */
@@ -315,6 +323,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
         oh->nattrs = 0;
         oh->attr_fheap_addr = HADDR_UNDEF;
         oh->name_bt2_addr = HADDR_UNDEF;
+        oh->max_attr_crt_idx = 0;
     } /* end else */
 
     /* First chunk size */
@@ -361,7 +370,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
         if(chunkno == 0) {
             /* First chunk's 'image' includes room for the object header prefix */
             oh->chunk[0].addr = addr;
-            oh->chunk[0].size = chunk_size + H5O_SIZEOF_HDR_OH(oh);
+            oh->chunk[0].size = chunk_size + H5O_SIZEOF_HDR(oh);
         } /* end if */
         else {
             oh->chunk[chunkno].addr = chunk_addr;
@@ -416,6 +425,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
             size_t	mesg_size;      /* Size of message read in */
             unsigned	id;             /* ID (type) of current message */
             uint8_t	flags;          /* Flags for current message */
+            H5O_crt_idx_t crt_idx = 0;  /* Creation index for current message */
 
             /* Decode message prefix info */
             if(oh->version == H5O_VERSION_1)
@@ -427,6 +437,8 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
 	    flags = *p++;
             if(oh->version == H5O_VERSION_1)
                 p += 3; /*reserved*/
+            else
+                UINT16DECODE(p, crt_idx);
 
             /* Try to detect invalidly formatted object header message that
              *  extends past end of chunk.
@@ -470,6 +482,7 @@ H5O_load(H5F_t *f, hid_t dxpl_id, haddr_t addr, const void UNUSED * _udata1,
                     oh->mesg[mesgno].type = H5O_msg_class_g[id];
                     oh->mesg[mesgno].dirty = FALSE;
                     oh->mesg[mesgno].flags = flags;
+                    oh->mesg[mesgno].crt_idx = crt_idx;
                     oh->mesg[mesgno].native = NULL;
                     oh->mesg[mesgno].raw = (uint8_t *)p;        /* Casting away const OK - QAK */
                     oh->mesg[mesgno].raw_size = mesg_size;
@@ -615,6 +628,9 @@ H5O_assert(oh);
             /* Version */
             *p++ = oh->version;
 
+            /* Flags */
+            *p++ = oh->flags;
+
             /* Number of messages */
             UINT16ENCODE(p, oh->nmesgs);
 
@@ -633,9 +649,10 @@ H5O_assert(oh);
             H5F_ENCODE_LENGTH(f, p, oh->nattrs);
             H5F_addr_encode(f, &p, oh->attr_fheap_addr);
             H5F_addr_encode(f, &p, oh->name_bt2_addr);
+            UINT16ENCODE(p, oh->max_attr_crt_idx);
 
             /* Chunk size */
-            UINT32ENCODE(p, (oh->chunk[0].size - H5O_SIZEOF_HDR_OH(oh)));
+            UINT32ENCODE(p, (oh->chunk[0].size - H5O_SIZEOF_HDR(oh)));
         } /* end if */
         else {
             /* Version */
@@ -651,13 +668,13 @@ H5O_assert(oh);
             UINT32ENCODE(p, oh->nlink);
 
             /* First chunk size */
-            UINT32ENCODE(p, (oh->chunk[0].size - H5O_SIZEOF_HDR_OH(oh)));
+            UINT32ENCODE(p, (oh->chunk[0].size - H5O_SIZEOF_HDR(oh)));
 
             /* Zero to alignment */
-            HDmemset(p, 0, (size_t)(H5O_SIZEOF_HDR_OH(oh) - 12));
-            p += (size_t)(H5O_SIZEOF_HDR_OH(oh) - 12);
+            HDmemset(p, 0, (size_t)(H5O_SIZEOF_HDR(oh) - 12));
+            p += (size_t)(H5O_SIZEOF_HDR(oh) - 12);
         } /* end else */
-        HDassert((size_t)(p - oh->chunk[0].image) == (size_t)(H5O_SIZEOF_HDR_OH(oh) - H5O_SIZEOF_CHKSUM_OH(oh)));
+        HDassert((size_t)(p - oh->chunk[0].image) == (size_t)(H5O_SIZEOF_HDR(oh) - H5O_SIZEOF_CHKSUM_OH(oh)));
 
         /* Mark chunk 0 as dirty, since the object header prefix has been updated */
         /* (this could be more sophisticated and track whether any prefix fields
@@ -752,27 +769,31 @@ H5O_dest(H5F_t UNUSED *f, H5O_t *oh)
     HDassert(oh->cache_info.is_dirty == FALSE);
 
     /* destroy chunks */
-    for(u = 0; u < oh->nchunks; u++) {
-        /* Verify that chunk is clean */
-        HDassert(oh->chunk[u].dirty == 0);
+    if(oh->chunk) {
+        for(u = 0; u < oh->nchunks; u++) {
+            /* Verify that chunk is clean */
+            HDassert(oh->chunk[u].dirty == 0);
+
+            oh->chunk[u].image = H5FL_BLK_FREE(chunk_image, oh->chunk[u].image);
+        } /* end for */
 
-        oh->chunk[u].image = H5FL_BLK_FREE(chunk_image, oh->chunk[u].image);
-    } /* end for */
-    if(oh->chunk)
         oh->chunk = (H5O_chunk_t *)H5FL_SEQ_FREE(H5O_chunk_t, oh->chunk);
+    } /* end if */
 
     /* destroy messages */
-    for(u = 0; u < oh->nmesgs; u++) {
-        /* Verify that message is clean */
-        HDassert(oh->mesg[u].dirty == 0);
+    if(oh->mesg) {
+        for(u = 0; u < oh->nmesgs; u++) {
+            /* Verify that message is clean */
+            HDassert(oh->mesg[u].dirty == 0);
+
+            H5O_msg_free_mesg(&oh->mesg[u]);
+        } /* end for */
 
-        H5O_msg_free_mesg(&oh->mesg[u]);
-    } /* end for */
-    if(oh->mesg)
         oh->mesg = (H5O_mesg_t *)H5FL_SEQ_FREE(H5O_mesg_t, oh->mesg);
+    } /* end if */
 
     /* destroy object header */
-    H5FL_FREE(H5O_t,oh);
+    H5FL_FREE(H5O_t, oh);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5O_dest() */
diff --git a/src/H5Ocont.c b/src/H5Ocont.c
index e5000bd..8a83f0a 100644
--- a/src/H5Ocont.c
+++ b/src/H5Ocont.c
@@ -64,6 +64,8 @@ const H5O_msg_class_t H5O_MSG_CONT[1] = {{
     NULL,			/* pre copy native value to file */
     NULL,			/* copy native value to file    */
     NULL, 		 	/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_cont_debug         	/*debugging                     */
 }};
 
diff --git a/src/H5Ocopy.c b/src/H5Ocopy.c
index 4e457ac..8c263f5 100644
--- a/src/H5Ocopy.c
+++ b/src/H5Ocopy.c
@@ -331,12 +331,12 @@ H5O_copy_header_real(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out */,
         HGOTO_ERROR(H5E_OHDR, H5E_CANTFLUSH, FAIL, "unable to flush object header messages")
 
     /* Allocate the destination object header and fill in header fields */
-    if(NULL == (oh_dst = H5FL_MALLOC(H5O_t)))
+    if(NULL == (oh_dst = H5FL_CALLOC(H5O_t)))
         HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, FAIL, "memory allocation failed")
 
     /* Initialize header information */
     oh_dst->version = oh_src->version;
-    oh_dst->nlink = 0;
+    oh_dst->flags = oh_src->flags;
     oh_dst->skipped_mesg_size = oh_src->skipped_mesg_size;
     oh_dst->sizeof_size = H5F_SIZEOF_SIZE(oloc_dst->file);
     oh_dst->sizeof_addr = H5F_SIZEOF_ADDR(oloc_dst->file);
@@ -412,7 +412,7 @@ H5O_copy_header_real(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out */,
         }
         HDassert(copy_type);
 
-        if(copy_type->pre_copy_file ) {
+        if(copy_type->pre_copy_file) {
             /*
              * Decode the message if necessary.  If the message is shared then do
              * a shared message, ignoring the message type.
@@ -547,7 +547,7 @@ H5O_copy_header_real(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out */,
     /* Calculate how big the destination object header will be on disk.
      * This isn't necessarily the same size as the original.
      */
-    dst_oh_size = H5O_SIZEOF_HDR_OH(oh_dst);
+    dst_oh_size = H5O_SIZEOF_HDR(oh_dst);
 
     /* Add space for messages. */
     for(mesgno = 0; mesgno < oh_dst->nmesgs; mesgno++) {
@@ -573,7 +573,7 @@ H5O_copy_header_real(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out */,
      * treatment.  This has to happen after the destination header has been
      * allocated.
      */
-    HDassert(H5O_SIZEOF_HDR_OH(oh_src) == H5O_SIZEOF_HDR_OH(oh_dst));
+    HDassert(H5O_SIZEOF_HDR(oh_src) == H5O_SIZEOF_HDR(oh_dst));
     HDassert(H5O_SIZEOF_MSGHDR_OH(oh_src) == H5O_SIZEOF_MSGHDR_OH(oh_dst));
     msghdr_size = H5O_SIZEOF_MSGHDR_OH(oh_src);
 
@@ -584,8 +584,8 @@ H5O_copy_header_real(const H5O_loc_t *oloc_src, H5O_loc_t *oloc_dst /*out */,
      * a magic number that isn't.
      */
     HDmemcpy(current_pos, oh_src->chunk[0].image,
-            (size_t)(H5O_SIZEOF_HDR_OH(oh_dst) - H5O_SIZEOF_CHKSUM_OH(oh_dst)));
-    current_pos += H5O_SIZEOF_HDR_OH(oh_dst) - H5O_SIZEOF_CHKSUM_OH(oh_dst);
+            (size_t)(H5O_SIZEOF_HDR(oh_dst) - H5O_SIZEOF_CHKSUM_OH(oh_dst)));
+    current_pos += H5O_SIZEOF_HDR(oh_dst) - H5O_SIZEOF_CHKSUM_OH(oh_dst);
 
     /* Copy each message that wasn't dirtied above */
     null_msgs = 0;
diff --git a/src/H5Odbg.c b/src/H5Odbg.c
index 6f32d24..7913f20 100644
--- a/src/H5Odbg.c
+++ b/src/H5Odbg.c
@@ -104,7 +104,7 @@ H5O_assert(const H5O_t *oh)
 
     /* Initialize the tracking variables */
     hdr_size = 0;
-    meta_space = H5O_SIZEOF_HDR_OH(oh) + (H5O_SIZEOF_CHKHDR_OH(oh) * (oh->nchunks - 1));
+    meta_space = H5O_SIZEOF_HDR(oh) + (H5O_SIZEOF_CHKHDR_OH(oh) * (oh->nchunks - 1));
     mesg_space = 0;
     free_space = 0;
     num_attrs = 0;
@@ -163,7 +163,7 @@ H5O_assert(const H5O_t *oh)
         /* Make certain that the message is completely in a chunk message area */
         HDassert(curr_msg->raw_size <= (oh->chunk[curr_msg->chunkno].size) - (H5O_SIZEOF_CHKSUM_OH(oh) + oh->chunk[curr_msg->chunkno].gap));
         if(curr_msg->chunkno == 0)
-            HDassert(curr_msg->raw >= oh->chunk[curr_msg->chunkno].image + (H5O_SIZEOF_HDR_OH(oh) - H5O_SIZEOF_CHKSUM_OH(oh)));
+            HDassert(curr_msg->raw >= oh->chunk[curr_msg->chunkno].image + (H5O_SIZEOF_HDR(oh) - H5O_SIZEOF_CHKSUM_OH(oh)));
         else
             HDassert(curr_msg->raw >= oh->chunk[curr_msg->chunkno].image + (H5O_SIZEOF_CHKHDR_OH(oh) - H5O_SIZEOF_CHKSUM_OH(oh)));
         HDassert(curr_msg->raw + curr_msg->raw_size <= (oh->chunk[curr_msg->chunkno].image + oh->chunk[curr_msg->chunkno].size) - (H5O_SIZEOF_CHKSUM_OH(oh) + oh->chunk[curr_msg->chunkno].gap));
@@ -273,7 +273,7 @@ H5O_debug_real(H5F_t *f, hid_t dxpl_id, H5O_t *oh, haddr_t addr, FILE *stream, i
 	      oh->version);
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
 	      "Header size (in bytes):",
-	      (unsigned)H5O_SIZEOF_HDR_OH(oh));
+	      (unsigned)H5O_SIZEOF_HDR(oh));
     HDfprintf(stream, "%*s%-*s %u\n", indent, "", fwidth,
 	      "Number of links:",
 	      oh->nlink);
@@ -343,7 +343,7 @@ H5O_debug_real(H5F_t *f, hid_t dxpl_id, H5O_t *oh, haddr_t addr, FILE *stream, i
 	if(0 == i) {
             if(H5F_addr_ne(oh->chunk[i].addr, addr))
                 HDfprintf(stream, "*** WRONG ADDRESS!\n");
-            chunk_size = oh->chunk[i].size - H5O_SIZEOF_HDR_OH(oh);
+            chunk_size = oh->chunk[i].size - H5O_SIZEOF_HDR(oh);
         } /* end if */
         else
             chunk_size = oh->chunk[i].size;
diff --git a/src/H5Odtype.c b/src/H5Odtype.c
index dd7a938..b055e4e 100644
--- a/src/H5Odtype.c
+++ b/src/H5Odtype.c
@@ -65,6 +65,8 @@ const H5O_msg_class_t H5O_MSG_DTYPE[1] = {{
     H5O_dtype_pre_copy_file,	/* pre copy native value to file */
     H5O_dtype_copy_file,	/* copy native value to file    */
     NULL,			/* post copy native value to file */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_dtype_debug		/* debug the message		*/
 }};
 
diff --git a/src/H5Oefl.c b/src/H5Oefl.c
index 7564e7f..14a8c7a 100644
--- a/src/H5Oefl.c
+++ b/src/H5Oefl.c
@@ -58,6 +58,8 @@ const H5O_msg_class_t H5O_MSG_EFL[1] = {{
     NULL,			/* pre copy native value to file */
     H5O_efl_copy_file,		/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_efl_debug	    	/*debug the message		*/
 }};
 
diff --git a/src/H5Ofill.c b/src/H5Ofill.c
index ea08489..62b8625 100644
--- a/src/H5Ofill.c
+++ b/src/H5Ofill.c
@@ -71,6 +71,8 @@ const H5O_msg_class_t H5O_MSG_FILL[1] = {{
     NULL,			/* pre copy native value to file	*/
     NULL,			/* copy native value to file		*/
     NULL,			/* post copy native value to file	*/
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_fill_debug              /*debug the message			*/
 }};
 
@@ -94,6 +96,8 @@ const H5O_msg_class_t H5O_MSG_FILL_NEW[1] = {{
     NULL,			/* pre copy native value to file	*/
     NULL,			/* copy native value to file		*/
     NULL,			/* post copy native value to file	*/
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_fill_new_debug		/*debug the message			*/
 }};
 
diff --git a/src/H5Oginfo.c b/src/H5Oginfo.c
index d8a75c1..152f5d3 100644
--- a/src/H5Oginfo.c
+++ b/src/H5Oginfo.c
@@ -62,6 +62,8 @@ const H5O_msg_class_t H5O_MSG_GINFO[1] = {{
     NULL,			/* pre copy native value to file */
     NULL,			/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_ginfo_debug          	/*debug the message             */
 }};
 
diff --git a/src/H5Olayout.c b/src/H5Olayout.c
index e161d3c..daa303d 100644
--- a/src/H5Olayout.c
+++ b/src/H5Olayout.c
@@ -65,6 +65,8 @@ const H5O_msg_class_t H5O_MSG_LAYOUT[1] = {{
     NULL,			/* pre copy native value to file */
     H5O_layout_copy_file,       /* copy native value to file    */
     NULL,		        /* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_layout_debug       	/*debug the message             */
 }};
 
diff --git a/src/H5Olinfo.c b/src/H5Olinfo.c
index d6267b0..2e62ee2 100644
--- a/src/H5Olinfo.c
+++ b/src/H5Olinfo.c
@@ -70,6 +70,8 @@ const H5O_msg_class_t H5O_MSG_LINFO[1] = {{
     NULL,			/* pre copy native value to file */
     H5O_linfo_copy_file,	/* copy native value to file    */
     H5O_linfo_post_copy_file,	/* post copy native value to file */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_linfo_debug          	/*debug the message             */
 }};
 
diff --git a/src/H5Olink.c b/src/H5Olink.c
index 5a58db3..1920635 100644
--- a/src/H5Olink.c
+++ b/src/H5Olink.c
@@ -74,6 +74,8 @@ const H5O_msg_class_t H5O_MSG_LINK[1] = {{
     H5O_link_pre_copy_file,	/* pre copy native value to file */
     H5O_link_copy_file,		/* copy native value to file    */
     H5O_link_post_copy_file,	/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_link_debug          	/*debug the message             */
 }};
 
diff --git a/src/H5Omessage.c b/src/H5Omessage.c
index 2e01516..628b3e9 100644
--- a/src/H5Omessage.c
+++ b/src/H5Omessage.c
@@ -61,6 +61,13 @@
         HDassert(decode_type->decode);                                        \
         if(NULL == ((MSG)->native = (decode_type->decode)((F), (DXPL), (MSG)->raw))) \
             HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, ERR, "unable to decode message") \
+                                                                              \
+        /* Set the message's "creation index", if it has one */		      \
+        if((MSG)->type->set_crt_index) {				      \
+            /* Set the creation index for the message */		      \
+            if(((MSG)->type->set_crt_index)((MSG)->native, (MSG)->crt_idx) < 0) \
+                HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, ERR, "unable to set creation index") \
+        } /* end if */							      \
     } /* end if */
 
 
@@ -1367,8 +1374,7 @@ H5O_msg_iterate_real(H5F_t *f, H5O_t *oh, const H5O_msg_class_t *type,
             else {
                 /* If the message is shared, get the real message it points to */
                 if(idx_msg->flags & H5O_MSG_FLAG_SHARED) {
-                    if(NULL == (native_mesg = H5O_shared_read(f, dxpl_id,
-                                idx_msg->native, idx_msg->type, NULL)))
+                    if(NULL == (native_mesg = H5O_shared_read(f, dxpl_id, idx_msg->native, idx_msg->type, NULL)))
                         HGOTO_ERROR(H5E_OHDR, H5E_BADMESG, FAIL, "unable to read shared message")
                     native_mesg_alloc = TRUE;
                 } /* end if */
@@ -1835,8 +1841,9 @@ done:
  *-------------------------------------------------------------------------
  */
 void *
-H5O_msg_copy_file(const H5O_msg_class_t *copy_type, const H5O_msg_class_t *mesg_type, H5F_t *file_src, void *native_src,
-    H5F_t *file_dst, hid_t dxpl_id, hbool_t *shared, H5O_copy_t *cpy_info, void *udata)
+H5O_msg_copy_file(const H5O_msg_class_t *copy_type, const H5O_msg_class_t *mesg_type,
+    H5F_t *file_src, void *native_src, H5F_t *file_dst, hid_t dxpl_id,
+    hbool_t *shared, H5O_copy_t *cpy_info, void *udata)
 {
     void        *native_mesg=NULL;
     void        *shared_mesg=NULL;
@@ -1848,8 +1855,8 @@ H5O_msg_copy_file(const H5O_msg_class_t *copy_type, const H5O_msg_class_t *mesg_
 
     /* check args */
     HDassert(copy_type);
-    HDassert(mesg_type);
     HDassert(copy_type->copy_file);
+    HDassert(mesg_type);
     HDassert(file_src);
     HDassert(native_src);
     HDassert(file_dst);
@@ -1991,6 +1998,13 @@ H5O_new_mesg(H5F_t *f, H5O_t *oh, unsigned *mesg_flags, const H5O_msg_class_t *o
     if((ret_value = H5O_alloc(f, dxpl_id, oh, orig_type, size, oh_flags_ptr)) == UFAIL)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, UFAIL, "unable to allocate space for message")
 
+    /* Get the message's "creation index", if it has one */
+    if(orig_type->get_crt_index) {
+        /* Retrieve the creation index for the message */
+        if((orig_type->get_crt_index)(orig_mesg, &oh->mesg[ret_value].crt_idx) < 0)
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTGET, UFAIL, "unable to retrieve creation index")
+    } /* end if */
+
     /* Increment any links in message */
     if((*new_type)->link && ((*new_type)->link)(f, dxpl_id, (*new_mesg)) < 0)
         HGOTO_ERROR(H5E_OHDR, H5E_LINKCOUNT, UFAIL, "unable to adjust shared object link count")
@@ -2138,6 +2152,13 @@ H5O_delete_mesg(H5F_t *f, hid_t dxpl_id, H5O_mesg_t *mesg, hbool_t adj_link)
             HDassert(type->decode);
             if(NULL == (mesg->native = (type->decode)(f, dxpl_id, mesg->raw)))
                 HGOTO_ERROR(H5E_OHDR, H5E_CANTDECODE, FAIL, "unable to decode message")
+
+            /* Set the message's "creation index", if it has one */
+            if(mesg->type->set_crt_index) {
+                /* Set the creation index for the message */
+                if((mesg->type->set_crt_index)(mesg->native, mesg->crt_idx) < 0)
+                    HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, FAIL, "unable to set creation index")
+            } /* end if */
         } /* end if */
 
         /* Check if this message needs to be removed from the SOHM table if
diff --git a/src/H5Omtime.c b/src/H5Omtime.c
index ccff078..77d9c87 100644
--- a/src/H5Omtime.c
+++ b/src/H5Omtime.c
@@ -65,6 +65,8 @@ const H5O_msg_class_t H5O_MSG_MTIME[1] = {{
     NULL,			/* pre copy native value to file */
     NULL,			/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_mtime_debug		/*debug the message		*/
 }};
 
@@ -89,6 +91,8 @@ const H5O_msg_class_t H5O_MSG_MTIME_NEW[1] = {{
     NULL,			/* pre copy native value to file */
     NULL,			/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_mtime_debug		/*debug the message		*/
 }};
 
diff --git a/src/H5Oname.c b/src/H5Oname.c
index 2314682..002d7e8 100644
--- a/src/H5Oname.c
+++ b/src/H5Oname.c
@@ -62,6 +62,8 @@ const H5O_msg_class_t H5O_MSG_NAME[1] = {{
     NULL,			/* pre copy native value to file */
     NULL,			/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_name_debug         	/*debug the message             */
 }};
 
diff --git a/src/H5Onull.c b/src/H5Onull.c
index e1d1c6f..5399112 100644
--- a/src/H5Onull.c
+++ b/src/H5Onull.c
@@ -31,23 +31,25 @@
 
 /* This message derives from H5O message class */
 const H5O_msg_class_t H5O_MSG_NULL[1] = {{
-    H5O_NULL_ID,            /*message id number             */
-    "null",                 /*message name for debugging    */
-    0,                      /*native message size           */
-    NULL,                   /*no decode method              */
-    NULL,                   /*no encode method              */
-    NULL,                   /*no copy method                */
-    NULL,                   /*no size method                */
-    NULL,                   /*no reset method               */
-    NULL,                   /*no free method                */
-    NULL,		    /*no file delete method         */
-    NULL,		    /*no link method		    */
-    NULL,		    /*no get share method	    */
-    NULL,	            /*no set share method	    */
-    NULL,	            /*no is_shared method	    */
-    NULL,		    /*no pre copy native value to file */
-    NULL,		    /*no copy native value to file    */
-    NULL,		    /*no post copy native value to file    */
-    NULL                    /*no debug method               */
+    H5O_NULL_ID,            	/*message id number             */
+    "null",                 	/*message name for debugging    */
+    0,                      	/*native message size           */
+    NULL,                   	/*no decode method              */
+    NULL,                   	/*no encode method              */
+    NULL,                   	/*no copy method                */
+    NULL,                   	/*no size method                */
+    NULL,                   	/*no reset method               */
+    NULL,                   	/*no free method                */
+    NULL,		    	/*no file delete method         */
+    NULL,		    	/*no link method		*/
+    NULL,		    	/*no get share method	        */
+    NULL,	            	/*no set share method	        */
+    NULL,	            	/*no is_shared method	        */
+    NULL,		    	/*no pre copy native value to file */
+    NULL,		    	/*no copy native value to file  */
+    NULL,		    	/*no post copy native value to file */
+    NULL,			/*no get creation index		*/
+    NULL,			/*no set creation index		*/
+    NULL                    	/*no debug method               */
 }};
 
diff --git a/src/H5Opkg.h b/src/H5Opkg.h
index ddd7799..a66cad4 100644
--- a/src/H5Opkg.h
+++ b/src/H5Opkg.h
@@ -30,6 +30,8 @@
 #define H5O_NMESGS	8 		/*initial number of messages	     */
 #define H5O_NCHUNKS	2		/*initial number of chunks	     */
 #define H5O_MIN_SIZE	32		/*min obj header data size	     */
+#define H5O_MSG_TYPES   19              /* # of types of messages            */
+#define H5O_MAX_CRT_ORDER_IDX 65535     /* Max. creation order index value   */
 
 /* Versions of object header structure */
 
@@ -55,7 +57,7 @@
  */
 #define H5O_ALIGN_OLD(X)	(8 * (((X) + 7) / 8))
 #define H5O_ALIGN_VERS(V, X)						      \
-     (((V) == H5O_VERSION_1) ?						      \
+    (((V) == H5O_VERSION_1) ?						      \
 		H5O_ALIGN_OLD(X)					      \
         :								      \
 		(X)							      \
@@ -78,100 +80,106 @@
 /*
  * Size of object header prefix.
  */
-#define H5O_SIZEOF_HDR_VERS(V,SOFS,SOFA)				      \
-     (((V) == H5O_VERSION_1) ?						      \
-        H5O_ALIGN_OLD(1 +	/*version number	*/		      \
-                  1 +		/*reserved 		*/		      \
-                  2 +		/*number of messages	*/		      \
-                  4 +		/*reference count	*/		      \
-                  4)		/*chunk data size	*/		      \
+#define H5O_SIZEOF_HDR(O)						      \
+    (((O)->version == H5O_VERSION_1)  					      \
+        ?								      \
+            H5O_ALIGN_OLD(1 +	/*version number	*/		      \
+                1 +		/*reserved 		*/		      \
+                2 +		/*number of messages	*/		      \
+                4 +		/*reference count	*/		      \
+                4)		/*chunk data size	*/		      \
         :								      \
-		(H5O_SIZEOF_MAGIC +	/*magic number  	*/	      \
-                  1 +		/*version number 	*/		      \
-                  2 +		/*number of messages	*/		      \
-                  4 +		/*reference count	*/		      \
-                  4 +		/*access time		*/		      \
-                  4 +		/*modification time	*/		      \
-                  4 +		/*change time		*/		      \
-                  4 +		/*birth time		*/		      \
-                  2 +		/*max compact attributes	*/	      \
-                  2 +		/*min dense attributes	*/		      \
-                  (SOFS) +	/*# of attributes	*/		      \
-                  (SOFA) +	/*addr of attribute heap	*/	      \
-                  (SOFA) +	/*addr of attribute name index	*/	      \
-                  4 +		/*chunk data size	*/		      \
-                  H5O_SIZEOF_CHKSUM)	/*checksum size	        */	      \
+            (H5O_SIZEOF_MAGIC +	/*magic number  	*/		      \
+                1 +		/*version number 	*/		      \
+                1 +		/*flags		 	*/		      \
+                2 +		/*number of messages	*/		      \
+                4 +		/*reference count	*/		      \
+                4 +		/*access time		*/		      \
+                4 +		/*modification time	*/		      \
+                4 +		/*change time		*/		      \
+                4 +		/*birth time		*/		      \
+                2 +		/*max compact attributes	*/	      \
+                2 +		/*min dense attributes	*/		      \
+                (O)->sizeof_size +	/*# of attributes	*/		      \
+                (O)->sizeof_addr +	/*addr of attribute heap	*/	      \
+                (O)->sizeof_addr +	/*addr of attribute name index	*/	      \
+                2 +		/*max attr. creation index	*/	      \
+                4 +		/*chunk data size	*/		      \
+                H5O_SIZEOF_CHKSUM)	/*checksum size	        */	      \
     )
-#define H5O_SIZEOF_HDR_OH(O)						      \
-     H5O_SIZEOF_HDR_VERS((O)->version, (O)->sizeof_size, (O)->sizeof_addr)
-#define H5O_SIZEOF_HDR_F(F)						      \
-     H5O_SIZEOF_HDR_VERS(H5F_USE_LATEST_FORMAT(F) ? H5O_VERSION_LATEST : H5O_VERSION_1, H5F_SIZEOF_SIZE(F), H5F_SIZEOF_ADDR(F))
 
 /*
  * Size of object header message prefix
  */
 #define H5O_SIZEOF_MSGHDR_VERS(V)					      \
-     (((V) == H5O_VERSION_1) ?						      \
-         H5O_ALIGN_OLD(2 +	/*message type		*/			      \
-                   2 +	/*sizeof message data	*/			      \
-                   1 +	/*flags              	*/			      \
-                   3)	/*reserved		*/			      \
+    (((V) == H5O_VERSION_1)  						      \
+        ?								      \
+            H5O_ALIGN_OLD(2 +	/*message type		*/		      \
+                2 +		/*sizeof message data	*/		      \
+                1 +		/*flags              	*/		      \
+                3)		/*reserved		*/		      \
         :								      \
-                (1 +	/*message type		*/			      \
-                   2 + 	/*sizeof message data	*/			      \
-                   1)	/*flags              	*/			      \
+            (1 +		/*message type		*/		      \
+                2 + 		/*sizeof message data	*/		      \
+                1 +		/*flags              	*/		      \
+                2)		/*creation index     	*/		      \
     )
 #define H5O_SIZEOF_MSGHDR_OH(O)						      \
-     H5O_SIZEOF_MSGHDR_VERS((O)->version)
+    H5O_SIZEOF_MSGHDR_VERS((O)->version)
 #define H5O_SIZEOF_MSGHDR_F(F)						      \
-     H5O_SIZEOF_MSGHDR_VERS(H5F_USE_LATEST_FORMAT(F) ? H5O_VERSION_LATEST : H5O_VERSION_1)
+    H5O_SIZEOF_MSGHDR_VERS(H5F_USE_LATEST_FORMAT(F) ? H5O_VERSION_LATEST : H5O_VERSION_1)
 
 /*
  * Size of chunk "header" for each chunk
  */
 #define H5O_SIZEOF_CHKHDR_VERS(V)					      \
-     (((V) == H5O_VERSION_1) ?						      \
-                   0 +	/*no magic #  */				      \
-                   0 	/*no checksum */				      \
+    (((V) == H5O_VERSION_1)  						      \
+        ?								      \
+            0 +		/*no magic #  */				      \
+                0 	/*no checksum */				      \
         :								      \
-                   H5O_SIZEOF_MAGIC + 	/*magic #  */			      \
-                   H5O_SIZEOF_CHKSUM 	/*checksum */			      \
+            H5O_SIZEOF_MAGIC + 		/*magic #  */			      \
+                H5O_SIZEOF_CHKSUM 	/*checksum */			      \
     )
 #define H5O_SIZEOF_CHKHDR_OH(O)						      \
-     H5O_SIZEOF_CHKHDR_VERS((O)->version)
+    H5O_SIZEOF_CHKHDR_VERS((O)->version)
 
 /*
  * Size of checksum for each chunk
  */
 #define H5O_SIZEOF_CHKSUM_VERS(V)					      \
-     (((V) == H5O_VERSION_1) ?						      \
-                   0 	/*no checksum */				      \
+    (((V) == H5O_VERSION_1)  						      \
+        ?								      \
+            0 		/*no checksum */				      \
         :								      \
-                   H5O_SIZEOF_CHKSUM 	/*checksum */			      \
+            H5O_SIZEOF_CHKSUM 		/*checksum */			      \
     )
 #define H5O_SIZEOF_CHKSUM_OH(O)						      \
-     H5O_SIZEOF_CHKSUM_VERS((O)->version)
+    H5O_SIZEOF_CHKSUM_VERS((O)->version)
 
 
+/* The "message class" type */
 struct H5O_msg_class_t {
-    unsigned	id;				 /*message type ID on disk   */
-    const char	*name;				 /*for debugging             */
-    size_t	native_size;			 /*size of native message    */
+    unsigned	id;				/*message type ID on disk   */
+    const char	*name;				/*for debugging             */
+    size_t	native_size;			/*size of native message    */
     void	*(*decode)(H5F_t*, hid_t, const uint8_t*);
     herr_t	(*encode)(H5F_t*, uint8_t*, const void*);
-    void	*(*copy)(const void *, void *);  /*copy native value         */
+    void	*(*copy)(const void *, void *);	/*copy native value         */
     size_t	(*raw_size)(const H5F_t*, const void*);/*sizeof encoded message	*/
-    herr_t	(*reset)(void *);		 /*free nested data structs  */
-    herr_t	(*free)(void *);		 /*free main data struct  */
+    herr_t	(*reset)(void *);		/*free nested data structs  */
+    herr_t	(*free)(void *);		/*free main data struct  */
     herr_t	(*del)(H5F_t *, hid_t, const void *, hbool_t); /* Delete space in file referenced by this message */
     herr_t	(*link)(H5F_t *, hid_t, const void *); /* Increment any links in file reference by this message */
     void	*(*get_share)(const void*, struct H5O_shared_t*);    /* Get shared information */
     herr_t	(*set_share)(void*, const struct H5O_shared_t*);    /* Set shared information */
-    htri_t	(*can_share)(const void*);      /* Is message allowed to be shared? */
-    htri_t	(*is_shared)(const void*);      /* Is message shared? */
+    htri_t	(*can_share)(const void *);	/* Is message allowed to be shared? */
+    htri_t	(*is_shared)(const void *);	/* Is message shared? */
     herr_t	(*pre_copy_file)(H5F_t *, const H5O_msg_class_t *, const void *, hbool_t *, const H5O_copy_t *, void *); /*"pre copy" action when copying native value to file */
     void	*(*copy_file)(H5F_t *, const H5O_msg_class_t *, void *, H5F_t *, hid_t, H5O_copy_t *, void *); /*copy native value to file */
     herr_t	(*post_copy_file)(const H5O_loc_t *, const void *, H5O_loc_t *, void *, hid_t, H5O_copy_t *); /*"post copy" action when copying native value to file */
+    herr_t      (*get_crt_index)(const void *, H5O_crt_idx_t *);	/* Get message's creation index */
+    herr_t      (*set_crt_index)(void *, H5O_crt_idx_t);	/* Set message's creation index */
     herr_t	(*debug)(H5F_t*, hid_t, const void*, FILE*, int, int);
 };
 
@@ -179,6 +187,7 @@ typedef struct H5O_mesg_t {
     const H5O_msg_class_t	*type;	/*type of message		     */
     hbool_t		dirty;		/*raw out of date wrt native	     */
     uint8_t		flags;		/*message flags			     */
+    H5O_crt_idx_t       crt_idx;        /*message creation index	     */
     unsigned		chunkno;	/*chunk number for this mesg	     */
     void		*native;	/*native format message		     */
     uint8_t		*raw;		/*ptr to raw data		     */
@@ -204,6 +213,7 @@ struct H5O_t {
     /* Object information (stored) */
     unsigned	version;		/*version number		     */
     unsigned	nlink;			/*link count			     */
+    unsigned	flags;			/*flags				     */
 
     /* Time information (stored, for versions > 1) */
     time_t      atime;                  /*access time 			     */
@@ -217,8 +227,9 @@ struct H5O_t {
     hsize_t     nattrs;                 /* Number of attributes in the group */
     haddr_t     attr_fheap_addr;        /* Address of fractal heap for storing "dense" attributes */
     haddr_t     name_bt2_addr;          /* Address of v2 B-tree for indexing names of attributes */
+    H5O_crt_idx_t max_attr_crt_idx;     /* Maximum attribute creation index used */
 
-    /* Message management (stored, in chunks) */
+    /* Message management (stored, encoded in chunks) */
     size_t	nmesgs;			/*number of messages		     */
     size_t	alloc_nmesgs;		/*number of message slots	     */
     H5O_mesg_t	*mesg;			/*array of messages		     */
@@ -272,7 +283,7 @@ typedef union {
 H5_DLLVAR const H5AC_class_t H5AC_OHDR[1];
 
 /* Header message ID to class mapping */
-H5_DLLVAR const H5O_msg_class_t *const H5O_msg_class_g[19];
+H5_DLLVAR const H5O_msg_class_t *const H5O_msg_class_g[H5O_MSG_TYPES];
 
 /* Header object ID to class mapping */
 H5_DLLVAR const H5O_obj_class_t *const H5O_obj_class_g[3];
diff --git a/src/H5Opline.c b/src/H5Opline.c
index 7ec6e9f..194b8b6 100644
--- a/src/H5Opline.c
+++ b/src/H5Opline.c
@@ -63,6 +63,8 @@ const H5O_msg_class_t H5O_MSG_PLINE[1] = {{
     H5O_pline_pre_copy_file,	/* pre copy native value to file */
     NULL,			/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_pline_debug		/* debug the message		*/
 }};
 
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index e1a08ce..1076441 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -45,13 +45,20 @@
 typedef struct H5O_msg_class_t H5O_msg_class_t;
 typedef struct H5O_t H5O_t;
 
-/* Fractal heap ID type for shared message heap IDs.  The length of a heap ID
- * depends on how the heap is configured; currently they're seven bytes long
- * but are stored in 8-byte fields in memory.
+/* Values used to create the shared message & attribute heaps */
+/* (Note that these parameters have been tuned so that the resulting heap ID
+ *      is exactly 8 bytes.  This is an efficient size as it can be stored
+ *      directly in an 8 byte integer in memory, think carefully before changing it.
+ *      -QAK)
  */
-#define H5SM_FHEAP_ID_LEN 8
-typedef uint64_t H5SM_fheap_id_t;
-
+#define H5O_FHEAP_MAN_WIDTH                     4
+#define H5O_FHEAP_MAN_START_BLOCK_SIZE          1024
+#define H5O_FHEAP_MAN_MAX_DIRECT_SIZE           (64 * 1024)
+#define H5O_FHEAP_MAN_MAX_INDEX                 40
+#define H5O_FHEAP_MAN_START_ROOT_ROWS           1
+#define H5O_FHEAP_CHECKSUM_DBLOCKS              TRUE
+#define H5O_FHEAP_MAX_MAN_SIZE                  (4 * 1024)
+#define H5O_FHEAP_ID_LEN                        8
 
 /* Object header macros */
 #define H5O_MESG_MAX_SIZE	65536	/*max obj header message size	     */
@@ -77,6 +84,12 @@ typedef uint64_t H5SM_fheap_id_t;
 /* ========= Object Copy properties ============ */
 #define H5O_CPY_OPTION_NAME 		"copy object"           /* Copy options */
 
+/* Typedef for creation indexes */
+typedef uint32_t H5O_crt_idx_t;
+
+/* Fractal heap ID type for shared message & attribute heap IDs. */
+typedef uint64_t H5O_fheap_id_t;
+
 /* The object location information for an object */
 typedef struct H5O_loc_t {
     H5F_t       *file;          /* File that object header is located within */
@@ -143,7 +156,7 @@ typedef struct H5O_shared_t {
     unsigned flags;             /* flags describing how message is shared */
     union {
         H5O_loc_t	oloc;		/* object location info		     */
-        H5SM_fheap_id_t heap_id;        /* ID within the SOHM heap           */
+        H5O_fheap_id_t  heap_id;        /* ID within the SOHM heap           */
     } u;
 } H5O_shared_t;
 
diff --git a/src/H5Osdspace.c b/src/H5Osdspace.c
index d90ee3f..89bfdda 100644
--- a/src/H5Osdspace.c
+++ b/src/H5Osdspace.c
@@ -59,6 +59,8 @@ const H5O_msg_class_t H5O_MSG_SDSPACE[1] = {{
     H5O_sdspace_pre_copy_file,	/* pre copy native value to file */
     NULL,			/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_sdspace_debug	        /* debug the message		    	*/
 }};
 
diff --git a/src/H5Oshared.c b/src/H5Oshared.c
index ab341d6..c06871e 100644
--- a/src/H5Oshared.c
+++ b/src/H5Oshared.c
@@ -72,6 +72,8 @@ const H5O_msg_class_t H5O_MSG_SHARED[1] = {{
     H5O_shared_pre_copy_file,	/* pre copy native value to file */
     H5O_shared_copy_file,	/* copy native value to file    */
     NULL,			/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_shared_debug	    	/*debug method				*/
 }};
 
@@ -83,7 +85,7 @@ const H5O_msg_class_t H5O_MSG_SHARED[1] = {{
 
 /* Newest version, which recognizes messages that are stored in the heap */
 #define H5O_SHARED_VERSION_3	3
-#define H5O_SHARED_VERSION	H5O_SHARED_VERSION_3
+#define H5O_SHARED_VERSION_LATEST	H5O_SHARED_VERSION_3
 
 /* Size of stack buffer for serialized messages */
 #define H5O_MESG_BUF_SIZE               128
@@ -288,20 +290,19 @@ H5O_shared_decode(H5F_t *f, hid_t UNUSED dxpl_id, const uint8_t *buf)
     HDassert(buf);
 
     /* Decode */
-    if(NULL == (mesg = H5MM_calloc (sizeof(H5O_shared_t))))
+    if(NULL == (mesg = H5MM_calloc(sizeof(H5O_shared_t))))
 	HGOTO_ERROR(H5E_RESOURCE, H5E_NOSPACE, NULL, "memory allocation failed")
 
     /* Version */
     version = *buf++;
-    if(version < H5O_SHARED_VERSION_1 || version > H5O_SHARED_VERSION)
+    if(version < H5O_SHARED_VERSION_1 || version > H5O_SHARED_VERSION_LATEST)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, NULL, "bad version number for shared object message")
 
     /* Get the shared information flags
      * Flags are unused before version 3.
      */
-    if(version >= H5O_SHARED_VERSION_2) {
+    if(version >= H5O_SHARED_VERSION_2)
         mesg->flags = *buf++;
-    }
     else {
         mesg->flags = H5O_COMMITTED_FLAG;
         buf++;
@@ -312,9 +313,8 @@ H5O_shared_decode(H5F_t *f, hid_t UNUSED dxpl_id, const uint8_t *buf)
         buf += 6;
 
     /* Body */
-    if(version == H5O_SHARED_VERSION_1) {
+    if(version == H5O_SHARED_VERSION_1)
         H5G_obj_ent_decode(f, &buf, &(mesg->u.oloc));
-    }
     else if (version >= H5O_SHARED_VERSION_2) {
         /* If this message is in the heap, copy a heap ID.
          * Otherwise, it is a named datatype, so copy an H5O_loc_t.
@@ -382,9 +382,8 @@ H5O_shared_encode(H5F_t *f, uint8_t *buf/*out*/, const void *_mesg)
     /* If this message is shared in the heap, we need to use version 3 of the
      * encoding and encode the SHARED_IN_HEAP flag.
      */
-    if(mesg->flags & H5O_SHARED_IN_HEAP_FLAG || H5F_USE_LATEST_FORMAT(f)) {
-        version = H5O_SHARED_VERSION;
-    }
+    if(mesg->flags & H5O_SHARED_IN_HEAP_FLAG || H5F_USE_LATEST_FORMAT(f))
+        version = H5O_SHARED_VERSION_LATEST;
     else {
         HDassert(mesg->flags & H5O_COMMITTED_FLAG);
         version = H5O_SHARED_VERSION_2; /* version 1 is no longer used */
@@ -396,12 +395,10 @@ H5O_shared_encode(H5F_t *f, uint8_t *buf/*out*/, const void *_mesg)
     /* Encode either the heap ID of the message or the address of the
      * object header that holds it.
      */
-    if(mesg->flags & H5O_SHARED_IN_HEAP_FLAG) {
+    if(mesg->flags & H5O_SHARED_IN_HEAP_FLAG)
         HDmemcpy(buf, &(mesg->u.heap_id), sizeof(mesg->u.heap_id));
-    }
-     else {
+    else
         H5F_addr_encode(f, &buf, mesg->u.oloc.addr);
-    }
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5O_shared_encode() */
@@ -480,15 +477,15 @@ H5O_shared_size(const H5F_t *f, const void *_mesg)
     if(shared->flags & H5O_COMMITTED_FLAG)
     {
         ret_value = 1 +			/*version			*/
-                1 +				/*the flags field		*/
-                H5F_SIZEOF_ADDR(f);		/*sharing by another obj hdr	*/
+            1 +				/*the flags field		*/
+            H5F_SIZEOF_ADDR(f);		/*sharing by another obj hdr	*/
     }
     else
     {
         HDassert(shared->flags & H5O_SHARED_IN_HEAP_FLAG);
         ret_value = 1 +			/*version			*/
-                1 +				/*the flags field	*/
-                H5SM_FHEAP_ID_LEN;		/* Shared in the heap   */
+            1 +				/*the flags field	*/
+            H5O_FHEAP_ID_LEN;		/* Shared in the heap   */
     }
 
     FUNC_LEAVE_NOAPI(ret_value);
diff --git a/src/H5Ostab.c b/src/H5Ostab.c
index 5865dca..850abab 100644
--- a/src/H5Ostab.c
+++ b/src/H5Ostab.c
@@ -70,6 +70,8 @@ const H5O_msg_class_t H5O_MSG_STAB[1] = {{
     NULL,			/* pre copy native value to file */
     H5O_stab_copy_file,		/* copy native value to file    */
     H5O_stab_post_copy_file,	/* post copy native value to file    */
+    NULL,			/* get creation index		*/
+    NULL,			/* set creation index		*/
     H5O_stab_debug         	/*debug the message             */
 }};
 
diff --git a/src/H5SM.c b/src/H5SM.c
index f37b913..11a0305 100755
--- a/src/H5SM.c
+++ b/src/H5SM.c
@@ -34,19 +34,6 @@
 /****************/
 /* Local Macros */
 /****************/
-/* Values used to create the SOHM heaps */
-/* (Note that these parameters have been tuned so that the resulting heap ID
- *      is exactly 8 bytes.  This is an efficient size and is also the same as
- *      the size of the attribute heap IDs, think carefully before changing it.
- *      -QAK)
- */
-#define H5SM_FHEAP_MAN_WIDTH                     4
-#define H5SM_FHEAP_MAN_START_BLOCK_SIZE          1024
-#define H5SM_FHEAP_MAN_MAX_DIRECT_SIZE           (64 * 1024)
-#define H5SM_FHEAP_MAN_MAX_INDEX                 40
-#define H5SM_FHEAP_MAN_START_ROOT_ROWS           1
-#define H5SM_FHEAP_CHECKSUM_DBLOCKS              TRUE
-#define H5SM_FHEAP_MAX_MAN_SIZE                  (4 * 1024)
 
 
 /******************/
@@ -430,9 +417,6 @@ H5SM_create_index(H5F_t *f, H5SM_index_header_t *header, hid_t dxpl_id)
     haddr_t tree_addr=HADDR_UNDEF;   /* Address of SOHM B-tree */
     H5HF_create_t fheap_cparam;      /* Fractal heap creation parameters */
     H5HF_t *fheap = NULL;
-#ifndef NDEBUG
-    size_t fheap_id_len;             /* Size of a fractal heap ID */
-#endif /* NDEBUG */
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI(H5SM_create_index, FAIL)
@@ -465,14 +449,14 @@ H5SM_create_index(H5F_t *f, H5SM_index_header_t *header, hid_t dxpl_id)
 
     /* Create a heap to hold the shared messages that the list or B-tree will index */
     HDmemset(&fheap_cparam, 0, sizeof(fheap_cparam));
-    fheap_cparam.managed.width = H5SM_FHEAP_MAN_WIDTH;
-    fheap_cparam.managed.start_block_size = H5SM_FHEAP_MAN_START_BLOCK_SIZE;
-    fheap_cparam.managed.max_direct_size = H5SM_FHEAP_MAN_MAX_DIRECT_SIZE;
-    fheap_cparam.managed.max_index = H5SM_FHEAP_MAN_MAX_INDEX;
-    fheap_cparam.managed.start_root_rows = H5SM_FHEAP_MAN_START_ROOT_ROWS;
-    fheap_cparam.checksum_dblocks = H5SM_FHEAP_CHECKSUM_DBLOCKS;
+    fheap_cparam.managed.width = H5O_FHEAP_MAN_WIDTH;
+    fheap_cparam.managed.start_block_size = H5O_FHEAP_MAN_START_BLOCK_SIZE;
+    fheap_cparam.managed.max_direct_size = H5O_FHEAP_MAN_MAX_DIRECT_SIZE;
+    fheap_cparam.managed.max_index = H5O_FHEAP_MAN_MAX_INDEX;
+    fheap_cparam.managed.start_root_rows = H5O_FHEAP_MAN_START_ROOT_ROWS;
+    fheap_cparam.checksum_dblocks = H5O_FHEAP_CHECKSUM_DBLOCKS;
     fheap_cparam.id_len = 0;
-    fheap_cparam.max_man_size = H5SM_FHEAP_MAX_MAN_SIZE;
+    fheap_cparam.max_man_size = H5O_FHEAP_MAX_MAN_SIZE;
     if(NULL == (fheap = H5HF_create(f, dxpl_id, &fheap_cparam)))
         HGOTO_ERROR(H5E_HEAP, H5E_CANTINIT, FAIL, "unable to create fractal heap")
 
@@ -480,11 +464,14 @@ H5SM_create_index(H5F_t *f, H5SM_index_header_t *header, hid_t dxpl_id)
         HGOTO_ERROR(H5E_HEAP, H5E_CANTGETSIZE, FAIL, "can't get fractal heap address")
 
 #ifndef NDEBUG
+{
+    size_t fheap_id_len;             /* Size of a fractal heap ID */
+
     /* Sanity check ID length */
     if(H5HF_get_id_len(fheap, &fheap_id_len) < 0)
         HGOTO_ERROR(H5E_HEAP, H5E_CANTGETSIZE, FAIL, "can't get fractal heap ID length")
-    HDassert(fheap_id_len == H5SM_FHEAP_ID_LEN);
-    HDassert(sizeof(H5SM_fheap_id_t) == H5SM_FHEAP_ID_LEN);
+    HDassert(fheap_id_len == H5O_FHEAP_ID_LEN);
+}
 #endif /* NDEBUG */
 
 done:
@@ -1493,17 +1480,16 @@ H5SM_message_decode(const H5F_t UNUSED *f, const uint8_t *raw, void *_nrecord)
  *-------------------------------------------------------------------------
  */
 herr_t
-H5SM_reconstitute(H5O_shared_t *sh_mesg, const uint8_t *heap_id)
+H5SM_reconstitute(H5O_shared_t *sh_mesg, H5O_fheap_id_t heap_id)
 {
     FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_reconstitute)
 
     /* Sanity check args */
     HDassert(sh_mesg);
-    HDassert(heap_id);
 
     /* Set flag for shared message */
     sh_mesg->flags = H5O_SHARED_IN_HEAP_FLAG;
-    HDmemcpy(&sh_mesg->u.heap_id, heap_id, sizeof(sh_mesg->u.heap_id));
+    sh_mesg->u.heap_id = heap_id;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
 } /* end H5SM_reconstitute() */
diff --git a/src/H5SMbtree2.c b/src/H5SMbtree2.c
index b59304f..8e7b762 100755
--- a/src/H5SMbtree2.c
+++ b/src/H5SMbtree2.c
@@ -36,10 +36,10 @@
 /******************/
 
 /* Udata struct for call to H5SM_btree_compare_cb */
-typedef struct H5SM_compare_udata {
+typedef struct H5SM_compare_udata_t {
     H5SM_mesg_key_t *key;   /* Key; compare this against record in heap */
     herr_t ret;            /* Return value; set this to result of memcmp */
-} H5SM_compare_udata;
+} H5SM_compare_udata_t;
 
 /********************/
 /* Local Prototypes */
@@ -91,7 +91,7 @@ const H5B2_class_t H5SM_INDEX[1]={{   /* B-tree class information */
 static herr_t
 H5SM_btree_compare_cb(const void *obj, size_t obj_len, void *_udata)
 {
-    H5SM_compare_udata *udata = (H5SM_compare_udata *)_udata;
+    H5SM_compare_udata_t *udata = (H5SM_compare_udata_t *)_udata;
     herr_t ret_value = SUCCEED;
 
     FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_btree_compare_cb)
@@ -108,7 +108,8 @@ H5SM_btree_compare_cb(const void *obj, size_t obj_len, void *_udata)
     }
 
     FUNC_LEAVE_NOAPI(ret_value)
-}
+} /* end H5SM_btree_compare_cb() */
+
 
 /*-------------------------------------------------------------------------
  * Function:	H5SM_message_compare
@@ -134,7 +135,7 @@ H5SM_message_compare(const void *rec1, const void *rec2)
     int64_t hash_diff;  /* Has to be able to hold two 32-bit values */
     herr_t ret_value = 0;
 
-    FUNC_ENTER_NOAPI_NOINIT(H5SM_message_compare)
+    FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_message_compare)
 
     /* JAMES: might be able to spare a sentinel byte instead of worrying about
      * refcounts.  Here, we need to find a deleted message in a B-tree to
@@ -146,7 +147,7 @@ H5SM_message_compare(const void *rec1, const void *rec2)
     hash_diff -= mesg->hash;
 
     /* If the hash values match, make sure the messages are really the same */
-    if(0 == hash_diff)     {
+    if(0 == hash_diff) {
         /* Compare either the heap_ids directly (if the key has one)
          * or the encoded buffers
          */
@@ -154,13 +155,13 @@ H5SM_message_compare(const void *rec1, const void *rec2)
         {
             HDassert(key->encoding == NULL);
             ret_value = (herr_t) (key->message.fheap_id - mesg->fheap_id);
-        }
+        } /* end if */
         else
         {
             /* Hash values match, but we don't have a heap ID for the key.
              * Compare the encoded message with the one in the heap.
              */
-            H5SM_compare_udata udata;
+            H5SM_compare_udata_t udata;
             herr_t ret;
 
             /* Casting away const OK.  -JML */
@@ -171,8 +172,8 @@ H5SM_message_compare(const void *rec1, const void *rec2)
             HDassert(ret >= 0);
 
             ret_value = udata.ret;
-        }
-    }
+        } /* end else */
+    } /* end if */
     else {
         /* Compress 64-bit hash_diff to fit in an herr_t */
         if(hash_diff > 0)
@@ -203,7 +204,7 @@ H5SM_message_compare(const void *rec1, const void *rec2)
 static herr_t
 H5SM_btree_store(void *native, const void *udata)
 {
-    H5SM_mesg_key_t *key = (H5SM_mesg_key_t *)udata;
+    const H5SM_mesg_key_t *key = (const H5SM_mesg_key_t *)udata;
 
     FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_btree_store)
 
@@ -263,7 +264,7 @@ H5SM_btree_debug(FILE *stream, const H5F_t UNUSED *f, hid_t UNUSED dxpl_id,
 
     FUNC_ENTER_NOAPI_NOINIT_NOFUNC(H5SM_btree_debug)
 
-    HDfprintf(stream, "%*s%-*s {%a, %lo, %Hu}\n", indent, "", fwidth, "Record:",
+    HDfprintf(stream, "%*s%-*s {%a, %lo, %Hx}\n", indent, "", fwidth, "Record:",
         sohm->fheap_id, sohm->hash, sohm->ref_count);
 
     FUNC_LEAVE_NOAPI(SUCCEED)
@@ -302,10 +303,10 @@ H5SM_incr_ref(void *record, void *op_data, hbool_t *changed)
     *changed = TRUE;
 
     if(op_data)
-       *(H5SM_fheap_id_t *)op_data = message->fheap_id;
+       *(H5O_fheap_id_t *)op_data = message->fheap_id;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-}
+} /* end H5SM_incr_ref() */
 
 
 /*-------------------------------------------------------------------------
@@ -345,7 +346,7 @@ H5SM_decr_ref(void *record, void *op_data, hbool_t *changed)
        *(H5SM_sohm_t *)op_data = *message;
 
     FUNC_LEAVE_NOAPI(SUCCEED)
-}
+} /* end H5SM_decr_ref() */
 
 
 /*-------------------------------------------------------------------------
diff --git a/src/H5SMpkg.h b/src/H5SMpkg.h
index d17f6c5..1010b16 100755
--- a/src/H5SMpkg.h
+++ b/src/H5SMpkg.h
@@ -39,7 +39,7 @@
 
 #define H5SM_SOHM_ENTRY_SIZE(f) (4  /* Hash value */                         \
          + 4                        /* reference count*/                     \
-         + sizeof(H5SM_fheap_id_t)) /* size of heap ID on disk */
+         + sizeof(H5O_fheap_id_t))  /* size of heap ID on disk */
 
 #define H5SM_TABLE_SIZE(f) ( H5SM_TABLE_SIZEOF_MAGIC                         \
          + H5SM_SIZEOF_CHECKSUM)               /* Checksum */
@@ -95,7 +95,7 @@
 /* Typedef for a SOHM index node */
 typedef struct {
     uint32_t hash;		/* Hash value for OHM */
-    H5SM_fheap_id_t fheap_id;	/* ID of the OHM in the fractal heap */
+    H5O_fheap_id_t fheap_id;	/* ID of the OHM in the fractal heap */
     hsize_t ref_count;		/* Number of times this message is used */
 } H5SM_sohm_t;
 
diff --git a/src/H5SMprivate.h b/src/H5SMprivate.h
index 679b59f..fab6097 100755
--- a/src/H5SMprivate.h
+++ b/src/H5SMprivate.h
@@ -41,7 +41,7 @@ H5_DLL herr_t H5SM_get_info(H5F_t *f, unsigned *index_flags, unsigned *minsizes,
 H5_DLL htri_t H5SM_type_shared(H5F_t *f, unsigned type_id, hid_t dxpl_id);
 H5_DLL herr_t H5SM_get_fheap_addr(H5F_t *f, hid_t dxpl_id, unsigned type_id,
     haddr_t *fheap_addr);
-H5_DLL herr_t H5SM_reconstitute(H5O_shared_t *sh_mesg, const uint8_t *heap_id);
+H5_DLL herr_t H5SM_reconstitute(H5O_shared_t *sh_mesg, H5O_fheap_id_t heap_id);
 H5_DLL herr_t H5SM_get_refcount(H5F_t *f, hid_t dxpl_id, unsigned type_id,
     const H5O_shared_t *sh_mesg, hsize_t *ref_count);
 
diff --git a/test/stab.c b/test/stab.c
index 7f722fd..47dbbfe 100644
--- a/test/stab.c
+++ b/test/stab.c
@@ -426,9 +426,9 @@ lifecycle(hid_t fapl)
     /* Check that the object header is only one chunk and the space has been allocated correctly */
     if(H5Gget_objinfo(gid, ".", FALSE, &obj_stat) < 0) TEST_ERROR
 #ifdef H5_HAVE_LARGE_HSIZET
-    if(obj_stat.ohdr.size != 235) TEST_ERROR
+    if(obj_stat.ohdr.size != 250) TEST_ERROR
 #else /* H5_HAVE_LARGE_HSIZET */
-    if(obj_stat.ohdr.size != 215) TEST_ERROR
+    if(obj_stat.ohdr.size != 230) TEST_ERROR
 #endif /* H5_HAVE_LARGE_HSIZET */
     if(obj_stat.ohdr.free != 0) TEST_ERROR
     if(obj_stat.ohdr.nmesgs != 6) TEST_ERROR
@@ -452,11 +452,11 @@ lifecycle(hid_t fapl)
     /* Check that the object header is still one chunk and the space has been allocated correctly */
     if(H5Gget_objinfo(gid, ".", FALSE, &obj_stat) < 0) TEST_ERROR
 #ifdef H5_HAVE_LARGE_HSIZET
-    if(obj_stat.ohdr.size != 235) TEST_ERROR
+    if(obj_stat.ohdr.size != 250) TEST_ERROR
 #else /* H5_HAVE_LARGE_HSIZET */
-    if(obj_stat.ohdr.size != 215) TEST_ERROR
+    if(obj_stat.ohdr.size != 230) TEST_ERROR
 #endif /* H5_HAVE_LARGE_HSIZET */
-    if(obj_stat.ohdr.free != 112) TEST_ERROR
+    if(obj_stat.ohdr.free != 120) TEST_ERROR
     if(obj_stat.ohdr.nmesgs != 3) TEST_ERROR
     if(obj_stat.ohdr.nchunks != 1) TEST_ERROR