Updates to the VOL ID and object API calls.

This brings the H5VL code in line with the H5I code regarding
naming, parameter order, etc.

Several public API calls were affected by this change.

These changed names to reflect their use with VOL drivers:
    H5VLregister()          -->     H5VLregister_driver()
    H5VLregister_by_name()  -->     H5VLregister_driver_by_name()
    H5VLunregister()        -->     H5VLunregister_driver()
    H5VLis_registered()     -->     H5VLis_driver_registered()

This call was renamed to match H5Iregister(). The order of the first
two parameters also reversed and the object pointer is now const.
    H5VLobject_register()   -->     H5VLregister()

25 files changed, 331 insertions, 235 deletions

diff --git a/src/H5A.c b/src/H5A.c
index 3ac7ca2..b023c78 100644
--- a/src/H5A.c
+++ b/src/H5A.c
@@ -288,7 +288,7 @@ H5Acreate2(hid_t loc_id, const char *attr_name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_PLIST, H5E_CANTGET, H5I_INVALID_HID, "can't set property value for space id")
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Set location parameters */
@@ -301,7 +301,7 @@ H5Acreate2(hid_t loc_id, const char *attr_name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, H5I_INVALID_HID, "unable to create attribute")
 
     /* Register the new attribute and get an ID for it */
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize attribute handle")
 
 done:
@@ -398,7 +398,7 @@ H5Acreate_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Create the attribute */
@@ -407,7 +407,7 @@ H5Acreate_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, H5I_INVALID_HID, "unable to create attribute")
 
     /* Register the new attribute and get an ID for it */
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize attribute handle")
 
 done:
@@ -467,7 +467,7 @@ H5Aopen(hid_t loc_id, const char *attr_name, hid_t aapl_id)
     loc_params.obj_type     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Open the attribute */
@@ -476,7 +476,7 @@ H5Aopen(hid_t loc_id, const char *attr_name, hid_t aapl_id)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open attribute: '%s'", attr_name)
 
     /* Register the attribute and get an ID for it */
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize attribute handle")
 
 done:
@@ -550,7 +550,7 @@ H5Aopen_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.obj_type                     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if (NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if (NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Open the attribute */
@@ -559,7 +559,7 @@ H5Aopen_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, H5I_INVALID_HID, "can't open attribute")
 
     /* Register the attribute and get an ID for it */
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize attribute handle")
 
 done:
@@ -642,7 +642,7 @@ H5Aopen_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.obj_type                     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Open the attribute */
@@ -651,7 +651,7 @@ H5Aopen_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open attribute")
 
     /* Register the attribute and get an ID for it */
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize attribute handle")
 
 done:
@@ -973,7 +973,7 @@ H5Aget_name_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_ATTR, H5E_CANTSET, FAIL, "can't set access property list info")
 
     /* Get the object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     loc_params.type = H5VL_OBJECT_BY_IDX;
@@ -1118,7 +1118,7 @@ H5Aget_info_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* Get the object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Get the attribute information */
@@ -1182,7 +1182,7 @@ H5Aget_info_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.obj_type                     = H5I_get_type(loc_id);
 
     /* Get the object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Get the attribute information */
@@ -1230,7 +1230,7 @@ H5Arename(hid_t loc_id, const char *old_name, const char *new_name)
         loc_params.obj_type = H5I_get_type(loc_id);
 
         /* Get the location object */
-        if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+        if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
         /* Set up collective metadata if appropriate */
@@ -1295,7 +1295,7 @@ H5Arename_by_name(hid_t loc_id, const char *obj_name, const char *old_attr_name,
         loc_params.obj_type = H5I_get_type(loc_id);
 
         /* Get the location object */
-        if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+        if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
         /* Rename the attribute */
@@ -1373,7 +1373,7 @@ H5Aiterate2(hid_t loc_id, H5_index_t idx_type, H5_iter_order_t order,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the loc object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Iterate over attributes */
@@ -1463,7 +1463,7 @@ H5Aiterate_by_name(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.loc_data.loc_by_name.lapl_id = lapl_id;
 
     /* get the loc object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Iterate over attributes */
@@ -1518,7 +1518,7 @@ H5Adelete(hid_t loc_id, const char *name)
     loc_params.obj_type     = H5I_get_type(loc_id);
 
     /* Get the object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Delete the attribute */
@@ -1577,7 +1577,7 @@ H5Adelete_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
     loc_params.obj_type                     = H5I_get_type(loc_id);
 
     /* Get the object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Delete the attribute */
@@ -1648,7 +1648,7 @@ H5Adelete_by_idx(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Delete the attribute through the VOL */
@@ -1724,7 +1724,7 @@ H5Aexists(hid_t obj_id, const char *attr_name)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no attribute name")
 
     /* get the object */
-    if(NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     loc_params.type = H5VL_OBJECT_BY_SELF;
@@ -1777,7 +1777,7 @@ H5Aexists_by_name(hid_t loc_id, const char *obj_name, const char *attr_name,
         HGOTO_ERROR(H5E_ATTR, H5E_CANTSET, FAIL, "can't set access property list info")
 
     /* get the object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     loc_params.type = H5VL_OBJECT_BY_NAME;
diff --git a/src/H5Adeprec.c b/src/H5Adeprec.c
index 47983ea..cce9316 100644
--- a/src/H5Adeprec.c
+++ b/src/H5Adeprec.c
@@ -152,7 +152,7 @@ H5Acreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
     loc_params.obj_type     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Create the attribute */
@@ -161,7 +161,7 @@ H5Acreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_ATTR, H5E_CANTINIT, H5I_INVALID_HID, "unable to create attribute")
 
     /* Register the new attribute and get an ID for it */
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register attribute for ID")
 
 done:
@@ -218,7 +218,7 @@ H5Aopen_name(hid_t loc_id, const char *name)
     loc_params.obj_type     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if (NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if (NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Open the attribute */
@@ -227,7 +227,7 @@ H5Aopen_name(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open attribute")
 
     /* Register the attribute and get an ID for it */
-    if ((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
+    if ((ret_value = H5VL_register(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize attribute handle")
 
 done:
@@ -287,7 +287,7 @@ H5Aopen_idx(hid_t loc_id, unsigned idx)
     loc_params.obj_type                         = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Open the attribute */
@@ -296,7 +296,7 @@ H5Aopen_idx(hid_t loc_id, unsigned idx)
         HGOTO_ERROR(H5E_ATTR, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open attribute")
 
     /* Register the attribute and get an ID for it */
-    if((ret_value = H5VL_register_id(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_ATTR, attr, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize attribute handle")
 
 done:
@@ -342,7 +342,7 @@ H5Aget_num_attrs(hid_t loc_id)
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, (-1), "invalid location identifier")
 
     /* Get the number of attributes for the object */
diff --git a/src/H5D.c b/src/H5D.c
index 9f56197..eb40cc8 100644
--- a/src/H5D.c
+++ b/src/H5D.c
@@ -163,7 +163,7 @@ H5Dcreate2(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, H5I_INVALID_HID, "unable to create dataset")
 
     /* Get an atom for the dataset */
-    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize dataset handle")
 
 done:
@@ -256,7 +256,7 @@ H5Dcreate_anon(hid_t loc_id, hid_t type_id, hid_t space_id, hid_t dcpl_id,
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, H5I_INVALID_HID, "unable to create dataset")
 
     /* Get an atom for the dataset */
-    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register dataset")
 
 done:
@@ -319,7 +319,7 @@ H5Dopen2(hid_t loc_id, const char *name, hid_t dapl_id)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open dataset")
 
     /* Register an atom for the dataset */
-    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "can't register dataset atom")
 
 done:
diff --git a/src/H5Ddeprec.c b/src/H5Ddeprec.c
index 4abba93..58238bc 100644
--- a/src/H5Ddeprec.c
+++ b/src/H5Ddeprec.c
@@ -157,7 +157,7 @@ H5Dcreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Create the dataset through the VOL */
@@ -166,7 +166,7 @@ H5Dcreate1(hid_t loc_id, const char *name, hid_t type_id, hid_t space_id,
         HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, H5I_INVALID_HID, "unable to create dataset")
 
     /* Get an atom for the dataset */
-    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register dataset")
 
 done:
@@ -217,7 +217,7 @@ H5Dopen1(hid_t loc_id, const char *name)
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid location identifier")
 
     /* Open the dataset */
@@ -226,7 +226,7 @@ H5Dopen1(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open dataset")
 
     /* Get an atom for the dataset */
-    if((ret_value = H5VL_register_id(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_DATASET, dset, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "can't register dataset atom")
 
 done:
diff --git a/src/H5Dvirtual.c b/src/H5Dvirtual.c
index 89974b2..77047e9 100644
--- a/src/H5Dvirtual.c
+++ b/src/H5Dvirtual.c
@@ -2977,7 +2977,7 @@ H5D__virtual_refresh_source_dset(H5D_t **dset)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get native VOL driver ID")
 
     /* Get a temporary identifier for this source dataset */
-    if((temp_id = H5VL_object_register(*dset, H5I_DATASET, native_vol_id, FALSE)) < 0)
+    if((temp_id = H5VL_register_using_vol_id(H5I_DATASET, *dset, native_vol_id, FALSE)) < 0)
         HGOTO_ERROR(H5E_DATASET, H5E_CANTREGISTER, FAIL, "can't register (temporary) source dataset ID")
 
     /* Refresh source dataset */
diff --git a/src/H5F.c b/src/H5F.c
index 2dcafb9..a31dff3 100644
--- a/src/H5F.c
+++ b/src/H5F.c
@@ -677,7 +677,7 @@ H5Fcreate(const char *filename, unsigned flags, hid_t fcpl_id, hid_t fapl_id)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL driver")
 
     /* Get an atom for the file */
-    if((ret_value = H5VL_register_id(H5I_FILE, new_file, driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_FILE, new_file, driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize file handle")
 
 done:
@@ -757,7 +757,7 @@ H5Fopen(const char *filename, unsigned flags, hid_t fapl_id)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL driver")
 
     /* Get an ID for the file */
-    if((ret_value = H5VL_register_id(H5I_FILE, new_file, driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_FILE, new_file, driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize file handle")
 
 done:
@@ -794,7 +794,7 @@ H5Fflush(hid_t object_id, H5F_scope_t scope)
     }
 
     /* get the file object */
-    if(NULL == (vol_obj = H5VL_get_object(object_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(object_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Flush the object */
@@ -883,7 +883,7 @@ H5Freopen(hid_t file_id)
         HGOTO_ERROR(H5E_FILE, H5E_CANTINIT, H5I_INVALID_HID, "unable to reopen file")
 
     /* Get an atom for the file */
-    if((ret_value = H5VL_register_id(H5I_FILE, file, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_FILE, file, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize file handle")
 
 done:
@@ -1288,7 +1288,7 @@ H5Fget_name(hid_t obj_id, char *name/*out*/, size_t size)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, (-1), "not a file or file object")
 
     /* Get the file object */
-    if(NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, (-1), "invalid file identifier")
 
     /* Get the filename via the VOL */
@@ -1334,7 +1334,7 @@ H5Fget_info2(hid_t obj_id, H5F_info2_t *finfo)
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "not a file or file object")
 
     /* Get the file object */
-    if(NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Get the file information */
diff --git a/src/H5Fint.c b/src/H5Fint.c
index 230a744..6a57ca5 100644
--- a/src/H5Fint.c
+++ b/src/H5Fint.c
@@ -3303,7 +3303,7 @@ H5F__start_swmr_write(H5F_t *f)
         if(grp_dset_count > 0) {
             H5VL_object_t *vol_obj = NULL;
 
-            if(NULL == (vol_obj = H5VL_get_object(obj_ids[0])))
+            if(NULL == (vol_obj = H5VL_vol_object(obj_ids[0])))
                 HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
             vol_driver = vol_obj->driver;
diff --git a/src/H5G.c b/src/H5G.c
index 772d567..1d4667f 100644
--- a/src/H5G.c
+++ b/src/H5G.c
@@ -370,7 +370,7 @@ H5Gcreate2(hid_t loc_id, const char *name, hid_t lcpl_id, hid_t gcpl_id,
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, H5I_INVALID_HID, "unable to create group")
 
     /* Get an atom for the group */
-    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize group handle")
 
 done:
@@ -450,7 +450,7 @@ H5Gcreate_anon(hid_t loc_id, hid_t gcpl_id, hid_t gapl_id)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, H5I_INVALID_HID, "unable to create group")
 
     /* Get an atom for the group */
-    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize group handle")
 
 done:
@@ -511,7 +511,7 @@ H5Gopen2(hid_t loc_id, const char *name, hid_t gapl_id)
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open group")
 
     /* Register an ID for the group */
-    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register group")
 
 done:
diff --git a/src/H5Gdeprec.c b/src/H5Gdeprec.c
index ab73e7e..d2e991b 100644
--- a/src/H5Gdeprec.c
+++ b/src/H5Gdeprec.c
@@ -240,7 +240,7 @@ H5Gcreate1(hid_t loc_id, const char *name, size_t size_hint)
         HGOTO_ERROR(H5E_SYM, H5E_CANTINIT, H5I_INVALID_HID, "unable to create group")
 
     /* Get an atom for the group */
-    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register group")
 
 done:
@@ -302,7 +302,7 @@ H5Gopen1(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_SYM, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open group")
 
     /* Get an atom for the group */
-    if((ret_value = H5VL_register_id(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_GROUP, grp, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register group")
 
 done:
diff --git a/src/H5I.c b/src/H5I.c
index 7d445a5..e1d947c 100644
--- a/src/H5I.c
+++ b/src/H5I.c
@@ -764,7 +764,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5I_register_with_id
+ * Function:    H5I_register_using_existing_id
  *
  * Purpose:     Registers an OBJECT in a TYPE with the supplied ID for it.
  *              This routine will check to ensure the supplied ID is not already
@@ -773,14 +773,17 @@ done:
  *              registered (thus, it is possible to register one object under
  *              multiple IDs).
  *
+ * NOTE:        Intended for use in refresh calls, where we have to close
+ *              and re-open the underlying data, then hook the object back
+ *              up to the original ID.
+ *
  * Return:      SUCCEED/FAIL
  *
  *-------------------------------------------------------------------------
  */
 herr_t
-H5I_register_with_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t app_ref, hid_t id)
+H5I_register_using_existing_id(H5I_type_t type, void *object, hbool_t app_ref, hid_t existing_id)
 {
-    H5VL_object_t  *new_vol_obj = NULL;     /* pointer to new VOL object        */
     H5I_id_type_t  *type_ptr;               /* ptr to the type                  */
     H5I_id_info_t  *id_ptr;                 /* ptr to the new ID information    */
     herr_t          ret_value = SUCCEED;    /* return value                     */
@@ -789,10 +792,9 @@ H5I_register_with_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t
 
     /* Check arguments */
     HDassert(object);
-    HDassert(vol_driver);
 
     /* Make sure ID is not already in use */
-    if(NULL != (id_ptr = H5I__find_id(id)))
+    if(NULL != (id_ptr = H5I__find_id(existing_id)))
         HGOTO_ERROR(H5E_ATOM, H5E_BADRANGE, FAIL, "ID already in use")
 
     /* Make sure type number is valid */
@@ -806,36 +808,18 @@ H5I_register_with_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t
         HGOTO_ERROR(H5E_ATOM, H5E_BADGROUP, FAIL, "invalid type")
 
     /* Make sure requested ID belongs to object's type */
-    if(H5I_TYPE(id) != type)
+    if(H5I_TYPE(existing_id) != type)
         HGOTO_ERROR(H5E_ATOM, H5E_BADRANGE, FAIL, "invalid type for provided ID")
 
     /* Allocate new structure to house this ID */
     if(NULL == (id_ptr = H5FL_MALLOC(H5I_id_info_t)))
         HGOTO_ERROR(H5E_ATOM, H5E_NOSPACE, FAIL, "memory allocation failed")
 
-    /* Set up the new VOL object */
-    if(NULL == (new_vol_obj = H5FL_CALLOC(H5VL_object_t)))
-        HGOTO_ERROR(H5E_ATOM, H5E_CANTALLOC, FAIL, "can't allocate memory for VOL object");
-    new_vol_obj->driver = vol_driver;
-    new_vol_obj->data = object;
-
-    /* Bump the reference count on the VOL driver */
-    vol_driver->nrefs++;
-
     /* Create the struct & insert requested ID */
-    id_ptr->id          = id;
+    id_ptr->id          = existing_id;
     id_ptr->count       = 1; /* initial reference count*/
     id_ptr->app_count   = !!app_ref;
-    if(H5I_DATATYPE == type) {
-        void *dt = NULL;
-
-        if(NULL == (dt = (void *)H5T_construct_datatype(new_vol_obj)))
-            HGOTO_ERROR(H5E_ATOM, H5E_CANTINIT, FAIL, "can't construct datatype object");
-
-        id_ptr->obj_ptr     = dt;
-    }
-    else
-        id_ptr->obj_ptr     = new_vol_obj;
+    id_ptr->obj_ptr     = object;
 
     /* Insert into the type */
     if(H5SL_insert(type_ptr->ids, id_ptr, &id_ptr->id) < 0)
@@ -844,7 +828,7 @@ H5I_register_with_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5I_register_with_id() */
+} /* end H5I_register_using_existing_id() */
 
 
 /*-------------------------------------------------------------------------
@@ -2222,7 +2206,7 @@ H5I__get_file_id(hid_t obj_id, H5I_type_t type)
     FUNC_ENTER_STATIC
 
     /* Get the object pointer */
-    if (NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if (NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid identifier")
 
     /* Get the file through the VOL */
@@ -2237,7 +2221,7 @@ H5I__get_file_id(hid_t obj_id, H5I_type_t type)
 
     /* If the ID does not exist, register it with the VOL driver */
     if (H5I_INVALID_HID == ret_value) {
-        if ((ret_value = H5VL_register_id(H5I_FILE, file, vol_obj->driver, TRUE)) < 0)
+        if ((ret_value = H5VL_register(H5I_FILE, file, vol_obj->driver, TRUE)) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize file handle")
     }
     else {
diff --git a/src/H5Iprivate.h b/src/H5Iprivate.h
index 8fd7caa..9068b5f 100644
--- a/src/H5Iprivate.h
+++ b/src/H5Iprivate.h
@@ -67,13 +67,7 @@ typedef struct H5I_class_t {
 H5_DLL herr_t H5I_register_type(const H5I_class_t *cls);
 H5_DLL int64_t H5I_nmembers(H5I_type_t type);
 H5_DLL herr_t H5I_clear_type(H5I_type_t type, hbool_t force, hbool_t app_ref);
-H5_DLL hid_t H5I_register(H5I_type_t type, const void *object, hbool_t app_ref);
-H5_DLL herr_t H5I_register_with_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t app_ref, hid_t id);
-H5_DLL void *H5I_subst(hid_t id, const void *new_object);
-H5_DLL void *H5I_object(hid_t id);
-H5_DLL void *H5I_object_verify(hid_t id, H5I_type_t id_type);
 H5_DLL H5I_type_t H5I_get_type(hid_t id);
-H5_DLL void *H5I_remove(hid_t id);
 H5_DLL herr_t H5I_iterate(H5I_type_t type, H5I_search_func_t func, void *udata, hbool_t app_ref);
 H5_DLL int H5I_get_ref(hid_t id, hbool_t app_ref);
 H5_DLL int H5I_inc_ref(hid_t id, hbool_t app_ref);
@@ -83,6 +77,26 @@ H5_DLL int H5I_dec_app_ref_always_close(hid_t id);
 H5_DLL int H5I_dec_type_ref(H5I_type_t type);
 H5_DLL herr_t H5I_find_id(const void *object, H5I_type_t type, hid_t *id /*out*/);
 
+/* NOTE:    The object and ID functions below deal in non-VOL objects (i.e.;
+ *          H5S_t, etc.). Similar VOL calls exist in H5VLprivate.h. Use
+ *          the H5VL calls with objects that go through the VOL, such as
+ *          datasets and groups, and the H5I calls with objects
+ *          that do not, such as property lists and dataspaces. Datatypes
+ *          are can be either named, where they will use the VOL, or not,
+ *          and thus require special treatment. See the datatype docs for
+ *          how to handle this.
+ */
+
+/* Functions that manipulate objects */
+H5_DLL void *H5I_object(hid_t id);
+H5_DLL void *H5I_object_verify(hid_t id, H5I_type_t id_type);
+H5_DLL void *H5I_remove(hid_t id);
+H5_DLL void *H5I_subst(hid_t id, const void *new_object);
+
+/* ID registration functions */
+H5_DLL hid_t H5I_register(H5I_type_t type, const void *object, hbool_t app_ref);
+H5_DLL herr_t H5I_register_using_existing_id(H5I_type_t type, void *object, hbool_t app_ref, hid_t existing_id);
+
 /* Debugging functions */
 H5_DLL herr_t H5I_dump_ids_for_type(H5I_type_t type);
 
diff --git a/src/H5L.c b/src/H5L.c
index 656edec..0beafba 100644
--- a/src/H5L.c
+++ b/src/H5L.c
@@ -489,7 +489,7 @@ H5Lcreate_soft(const char *link_target, hid_t link_loc_id, const char *link_name
     loc_params.obj_type                     = H5I_get_type(link_loc_id);
 
     /* get the location object */
-    if(NULL == (vol_obj = (H5VL_object_t *)H5VL_get_object(link_loc_id)))
+    if(NULL == (vol_obj = (H5VL_object_t *)H5VL_vol_object(link_loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Get the plist structure */
@@ -580,12 +580,12 @@ H5Lcreate_hard(hid_t cur_loc_id, const char *cur_name,
 
     if(H5L_SAME_LOC != cur_loc_id) {
         /* Get the current location object */
-        if (NULL == (vol_obj1 = (H5VL_object_t *)H5VL_get_object(cur_loc_id)))
+        if (NULL == (vol_obj1 = (H5VL_object_t *)H5VL_vol_object(cur_loc_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
     }
     if(H5L_SAME_LOC != new_loc_id) {
         /* Get the new location object */
-        if(NULL == (vol_obj2 = (H5VL_object_t *)H5VL_get_object(new_loc_id)))
+        if(NULL == (vol_obj2 = (H5VL_object_t *)H5VL_vol_object(new_loc_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
     }
 
diff --git a/src/H5O.c b/src/H5O.c
index 77b9498..23b6dda7 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -135,7 +135,7 @@ H5Oopen(hid_t loc_id, const char *name, hid_t lapl_id)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open object")
 
     /* Get an atom for the object */
-    if((ret_value = H5VL_register_id(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize object handle")
 done:
     FUNC_LEAVE_API(ret_value)
@@ -207,7 +207,7 @@ H5Oopen_by_idx(hid_t loc_id, const char *group_name, H5_index_t idx_type,
                                               &opened_type, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL)))
         HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open object")
 
-    if((ret_value = H5VL_register_id(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize object handle")
 
 done:
@@ -276,7 +276,7 @@ H5Oopen_by_addr(hid_t loc_id, haddr_t addr)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open object")
 
     /* Register the dataset ID */
-    if((ret_value = H5VL_register_id(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize object handle")
 
 done:
@@ -350,12 +350,12 @@ H5Olink(hid_t obj_id, hid_t new_loc_id, const char *new_name, hid_t lcpl_id,
 
     if(H5L_SAME_LOC != obj_id) {
         /* get the location object */
-        if(NULL == (vol_obj1 = H5VL_get_object(obj_id)))
+        if(NULL == (vol_obj1 = H5VL_vol_object(obj_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
     }
     if(H5L_SAME_LOC != new_loc_id) {
         /* get the location object */
-        if(NULL == (vol_obj2 = H5VL_get_object(new_loc_id)))
+        if(NULL == (vol_obj2 = H5VL_vol_object(new_loc_id)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
     }
     /* Make sure that the VOL plugins are the same */
@@ -419,7 +419,7 @@ H5Oincr_refcount(hid_t object_id)
     loc_params.obj_type = H5I_get_type(object_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(object_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(object_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Set up collective metadata if appropriate */
@@ -470,7 +470,7 @@ H5Odecr_refcount(hid_t object_id)
     loc_params.obj_type = H5I_get_type(object_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(object_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(object_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Set up collective metadata if appropriate */
@@ -521,7 +521,7 @@ H5Oexists_by_name(hid_t loc_id, const char *name, hid_t lapl_id)
         HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, FAIL, "can't set access property list info")
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Set the location struct fields */
@@ -575,7 +575,7 @@ H5Oget_info2(hid_t loc_id, H5O_info_t *oinfo, unsigned fields)
     loc_params.obj_type     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Retrieve the object's information */
@@ -634,7 +634,7 @@ H5Oget_info_by_name2(hid_t loc_id, const char *name, H5O_info_t *oinfo,
     loc_params.obj_type                     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Retrieve the object's information */
@@ -700,7 +700,7 @@ H5Oget_info_by_idx2(hid_t loc_id, const char *group_name, H5_index_t idx_type,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Retrieve the object's information */
@@ -741,7 +741,7 @@ H5Oset_comment(hid_t obj_id, const char *comment)
     H5TRACE2("e", "i*s", obj_id, comment);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Set up collective metadata if appropriate */
@@ -805,7 +805,7 @@ H5Oset_comment_by_name(hid_t loc_id, const char *name, const char *comment,
     loc_params.obj_type                     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* (Re)set the object's comment */
@@ -845,7 +845,7 @@ H5Oget_comment(hid_t obj_id, char *comment, size_t bufsize)
     H5TRACE3("Zs", "i*sz", obj_id, comment, bufsize);
 
     /* Get the object */
-    if (NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if (NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, (-1), "invalid location identifier")
 
     /* Set fields in the location struct */
@@ -904,7 +904,7 @@ H5Oget_comment_by_name(hid_t loc_id, const char *name, char *comment, size_t buf
     loc_params.obj_type                     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, (-1), "invalid location identifier")
 
     /* Retrieve the object's comment */
@@ -974,7 +974,7 @@ H5Ovisit2(hid_t obj_id, H5_index_t idx_type, H5_iter_order_t order,
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid fields")
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Set location parameters */
@@ -1058,7 +1058,7 @@ H5Ovisit_by_name2(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, FAIL, "can't set access property list info")
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Set location parameters */
diff --git a/src/H5Odeprec.c b/src/H5Odeprec.c
index ead2028..68eb170 100644
--- a/src/H5Odeprec.c
+++ b/src/H5Odeprec.c
@@ -105,7 +105,7 @@ H5Oget_info1(hid_t loc_id, H5O_info_t *oinfo)
     loc_params.obj_type     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Retrieve the object's information */
@@ -157,7 +157,7 @@ H5Oget_info_by_name1(hid_t loc_id, const char *name, H5O_info_t *oinfo, hid_t la
     loc_params.obj_type                     = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Retrieve the object's information */
@@ -219,7 +219,7 @@ H5Oget_info_by_idx1(hid_t loc_id, const char *group_name, H5_index_t idx_type,
     loc_params.obj_type = H5I_get_type(loc_id);
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Retrieve the object's information */
@@ -284,7 +284,7 @@ H5Ovisit1(hid_t obj_id, H5_index_t idx_type, H5_iter_order_t order,
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "no callback operator specified")
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Set location parameters */
@@ -363,7 +363,7 @@ H5Ovisit_by_name1(hid_t loc_id, const char *obj_name, H5_index_t idx_type,
         HGOTO_ERROR(H5E_OHDR, H5E_CANTSET, FAIL, "can't set access property list info")
 
     /* Get the location object */
-    if(NULL == (vol_obj = H5VL_get_object(loc_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(loc_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid location identifier")
 
     /* Set location parameters */
diff --git a/src/H5Oflush.c b/src/H5Oflush.c
index 84095d9..40b6c6e 100644
--- a/src/H5Oflush.c
+++ b/src/H5Oflush.c
@@ -80,7 +80,7 @@ H5Oflush(hid_t obj_id)
     H5TRACE1("e", "i", obj_id);
 
     /* Check args */
-    if(NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Set up collective metadata if appropriate */
@@ -245,7 +245,7 @@ H5Orefresh(hid_t oid)
     H5TRACE1("e", "i", oid);
 
     /* Check args */
-    if(NULL == (vol_obj = H5VL_get_object(oid)))
+    if(NULL == (vol_obj = H5VL_vol_object(oid)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
 
     /* Set up collective metadata if appropriate */
@@ -323,7 +323,7 @@ H5O_refresh_metadata(hid_t oid, H5O_loc_t oloc)
          * The vol_obj will disappear when the underlying object is closed, so
          * we can't use that directly.
          */
-        if(NULL == (vol_obj = H5VL_get_object(oid)))
+        if(NULL == (vol_obj = H5VL_vol_object(oid)))
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object identifier")
         driver = vol_obj->driver;
 
@@ -501,7 +501,7 @@ H5O_refresh_metadata_reopen(hid_t oid, H5G_loc_t *obj_loc, H5VL_t *vol_driver, h
     } /* end switch */
 
     /* Re-register ID for the object */
-    if((H5I_register_with_id(type, object, vol_driver, TRUE, oid)) < 0)
+    if((H5VL_register_using_existing_id(type, object, vol_driver, TRUE, oid)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to re-register object ID after refresh")
 
 done:
diff --git a/src/H5R.c b/src/H5R.c
index 3e6517f..a2a7a14 100644
--- a/src/H5R.c
+++ b/src/H5R.c
@@ -189,7 +189,7 @@ H5Rdereference2(hid_t obj_id, hid_t oapl_id, H5R_type_t ref_type, const void *_r
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTSET, FAIL, "can't set access property list info")
 
     /* Get the VOL object */
-    if(NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if(NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid file identifier")
 
     /* Set location parameters */
@@ -204,7 +204,7 @@ H5Rdereference2(hid_t obj_id, hid_t oapl_id, H5R_type_t ref_type, const void *_r
                                               &opened_type, H5P_DATASET_XFER_DEFAULT, H5_REQUEST_NULL)))
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to dereference object")
 
-    if((ret_value = H5VL_register_id(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register object handle")
 
 done:
diff --git a/src/H5Rdeprec.c b/src/H5Rdeprec.c
index 9c1fcc5..f224cda 100644
--- a/src/H5Rdeprec.c
+++ b/src/H5Rdeprec.c
@@ -122,7 +122,7 @@ H5Rget_obj_type1(hid_t id, H5R_type_t ref_type, const void *ref)
     loc_params.obj_type = H5I_get_type(id);
 
     /* Get the vol object */
-    if (NULL == (vol_obj = H5VL_get_object(id)))
+    if (NULL == (vol_obj = H5VL_vol_object(id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5G_UNKNOWN, "invalid file identifier")
 
     /* Get the object information */
@@ -173,7 +173,7 @@ H5Rdereference1(hid_t obj_id, H5R_type_t ref_type, const void *_ref)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, H5I_INVALID_HID, "invalid reference pointer")
 
     /* Get the VOL object */
-    if (NULL == (vol_obj = H5VL_get_object(obj_id)))
+    if (NULL == (vol_obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "invalid file identifier")
 
     loc_params.type = H5VL_OBJECT_BY_REF;
@@ -188,7 +188,7 @@ H5Rdereference1(hid_t obj_id, H5R_type_t ref_type, const void *_ref)
         HGOTO_ERROR(H5E_REFERENCE, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to dereference object")
 
     /* Get an atom for the object */
-    if ((ret_value = H5VL_register_id(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
+    if ((ret_value = H5VL_register(opened_type, opened_obj, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize object handle")
 
 done:
diff --git a/src/H5Tcommit.c b/src/H5Tcommit.c
index 8f7b4de..09a0f3f 100644
--- a/src/H5Tcommit.c
+++ b/src/H5Tcommit.c
@@ -600,7 +600,7 @@ H5Topen2(hid_t loc_id, const char *name, hid_t tapl_id)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open named datatype")
 
     /* Register the type and return the ID */
-    if((ret_value = H5VL_register_id(H5I_DATATYPE, dt, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_DATATYPE, dt, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register named datatype")
 
 done:
diff --git a/src/H5Tdeprec.c b/src/H5Tdeprec.c
index 1b59c6b..0e45587 100644
--- a/src/H5Tdeprec.c
+++ b/src/H5Tdeprec.c
@@ -203,7 +203,7 @@ H5Topen1(hid_t loc_id, const char *name)
         HGOTO_ERROR(H5E_DATATYPE, H5E_CANTOPENOBJ, H5I_INVALID_HID, "unable to open named datatype")
 
     /* Register the type and return the ID */
-    if((ret_value = H5VL_register_id(H5I_DATATYPE, dt, vol_obj->driver, TRUE)) < 0)
+    if((ret_value = H5VL_register(H5I_DATATYPE, dt, vol_obj->driver, TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register named datatype")
 
 done:
diff --git a/src/H5VL.c b/src/H5VL.c
index 24e558c..85b991f 100644
--- a/src/H5VL.c
+++ b/src/H5VL.c
@@ -201,7 +201,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VLregister
+ * Function:    H5VLregister_driver
  *
  * Purpose:     Registers a new VOL driver as a member of the virtual object
  *              layer class.
@@ -210,17 +210,17 @@ done:
  *                          library is closed or the driver is
  *                          unregistered.
  *
- *              Failure:    A negative value (H5I_INVALID_HID).
+ *              Failure:    H5I_INVALID_HID
  *
  *-------------------------------------------------------------------------
  */
 hid_t
-H5VLregister(const H5VL_class_t *cls)
+H5VLregister_driver(const H5VL_class_t *cls)
 {
     H5VL_get_driver_ud_t op_data;
     hid_t ret_value = H5I_INVALID_HID;
 
-    FUNC_ENTER_API(FAIL)
+    FUNC_ENTER_API(H5I_INVALID_HID)
     H5TRACE1("i", "*x", cls);
 
     /* Check arguments */
@@ -246,16 +246,16 @@ H5VLregister(const H5VL_class_t *cls)
         HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, H5I_INVALID_HID, "VOL driver with the same name is already registered.")
 
     /* Create the new class ID */
-    if ((ret_value = H5VL_register(cls, sizeof(H5VL_class_t), TRUE)) < 0)
+    if ((ret_value = H5VL_register_driver(cls, sizeof(H5VL_class_t), TRUE)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL driver")
 
 done:
     FUNC_LEAVE_API(ret_value)
-} /* end H5VLregister() */
+} /* end H5VLregister_driver() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VLregister_by_name
+ * Function:    H5VLregister_driver_by_name
  *
  * Purpose:     Registers a new VOL driver as a member of the virtual object
  *              layer class.
@@ -264,17 +264,17 @@ done:
  *                          library is closed or the driver is
  *                          unregistered.
  *
- *              Failure:    A negative value.
+ *              Failure:    H5I_INVALID_HID
  *
  *-------------------------------------------------------------------------
  */
 hid_t
-H5VLregister_by_name(const char *name)
+H5VLregister_driver_by_name(const char *name)
 {
     H5VL_get_driver_ud_t    op_data;
     hid_t                   ret_value = H5I_INVALID_HID;
 
-    FUNC_ENTER_API(FAIL)
+    FUNC_ENTER_API(H5I_INVALID_HID)
     H5TRACE1("i", "*s", name);
 
     /* Check arguments */
@@ -306,21 +306,21 @@ H5VLregister_by_name(const char *name)
             HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, H5I_INVALID_HID, "unable to load VOL driver")
 
         /* Register the driver we loaded */
-        if ((ret_value = H5VL_register(cls, sizeof(H5VL_class_t), TRUE)) < 0)
+        if ((ret_value = H5VL_register_driver(cls, sizeof(H5VL_class_t), TRUE)) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register VOL driver ID")
     }
 
 done:
     FUNC_LEAVE_API(ret_value)
-} /* end H5VLregister_by_name() */
+} /* end H5VLregister_driver_by_name() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VLunregister
+ * Function:    H5VLunregister_driver
  *
- * Purpose:     Removes a vol driver ID from the library. This in no way affects
+ * Purpose:     Removes a VOL driver ID from the library. This in no way affects
  *              file access property lists which have been defined to use
- *              this vol driver or files which are already opened under with
+ *              this VOL driver or files which are already opened under with
  *              this driver.
  *
  * Return:      Success:    Non-negative
@@ -330,7 +330,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5VLunregister(hid_t vol_id)
+H5VLunregister_driver(hid_t vol_id)
 {
     H5VL_class_t *cls = NULL;
     herr_t ret_value = SUCCEED;       /* Return value */
@@ -348,11 +348,11 @@ H5VLunregister(hid_t vol_id)
 
 done:
     FUNC_LEAVE_API(ret_value)
-} /* end H5VLunregister() */
+} /* end H5VLunregister_driver() */
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VLis_registered
+ * Function:    H5VLis_driver_registered
  *
  * Purpose:     Tests whether a VOL class has been registered or not
  *
@@ -365,7 +365,7 @@ done:
  *-------------------------------------------------------------------------
  */
 htri_t
-H5VLis_registered(const char *name)
+H5VLis_driver_registered(const char *name)
 {
     H5VL_get_driver_ud_t op_data;
     htri_t ret_value = FALSE;     /* Return value */
@@ -385,7 +385,7 @@ H5VLis_registered(const char *name)
 
 done:
     FUNC_LEAVE_API(ret_value)
-} /* end H5VLis_registered() */
+} /* end H5VLis_driver_registered() */
 
 
 /*-------------------------------------------------------------------------
@@ -455,34 +455,39 @@ done:
 
 
 /*---------------------------------------------------------------------------
- * Function:	H5VLobject_register
+ * Function:	H5VLregister
  *
- * Purpose:     Public routine to create an HDF5 hid_t with library
- *              specific types, bypassing the limitation of H5Iregister.
+ * Purpose:     Public routine to register an object and get an ID given a
+ *              VOL driver ID.
  *
- * Return:      Success:    Non-negative
+ *              Unlike H5Iregister(), this API call can register library
+ *              types (e.g.; H5I_DATASET).
  *
- *              Failure:    Negative
+ * NOTE:        This API call is mainly intended for VOL driver authors.
+ *
+ * Return:      Success:    A valid HDF5 ID
+ *
+ *              Failure:    H5I_INVALID_HID
  *
  *---------------------------------------------------------------------------
  */
 hid_t
-H5VLobject_register(void *obj, H5I_type_t obj_type, hid_t driver_id)
+H5VLregister(H5I_type_t type, const void *obj, hid_t driver_id)
 {
-    hid_t ret_value = FAIL;
+    hid_t ret_value = H5I_INVALID_HID;
 
-    FUNC_ENTER_API(FAIL)
-    H5TRACE3("i", "*xIti", obj, obj_type, driver_id);
+    FUNC_ENTER_API(H5I_INVALID_HID)
+    H5TRACE3("i", "It*xi", type, obj, driver_id);
 
     if (NULL == obj)
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid object to register")
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "obj pointer can't be NULL")
 
-    if ((ret_value = H5VL_object_register(obj, obj_type, driver_id, TRUE)) < 0)
-        HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, FAIL, "unable to register object")
+    if ((ret_value = H5VL_register_using_vol_id(type, obj, driver_id, TRUE)) < 0)
+        HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register object")
 
 done:
     FUNC_LEAVE_API(ret_value)
-} /* H5VLobject_register */
+} /* H5VLregister */
 
 
 /*-------------------------------------------------------------------------
@@ -540,7 +545,7 @@ H5VLget_object(hid_t obj_id, void **obj)
     if (!obj)
         HGOTO_ERROR(H5E_ARGS, H5E_BADVALUE, FAIL, "invalid object pointer")
 
-    if (NULL == (*obj = H5VL_get_object(obj_id)))
+    if (NULL == (*obj = H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "ID does not contain a valid object")
 
 done:
diff --git a/src/H5VLint.c b/src/H5VLint.c
index 78ba6d9..e246989 100644
--- a/src/H5VLint.c
+++ b/src/H5VLint.c
@@ -213,20 +213,21 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:   H5VL_register_id
+ * Function:    H5VL_register
  *
- * Purpose:    Wrapper to register an object ID with a VOL aux struct 
- *             and increment ref count on VOL driver ID
+ * Purpose:     VOL-aware version of H5I_register. Constructs an H5VL_object_t
+ *              from the passed-in object and registers that. Does the right
+ *              thing with datatypes, which are complicated under the VOL.
  *
- * Return:     Success:     A valid HDF5 ID
+ * Return:      Success:    A valid HDF5 ID
  *              Failure:    H5I_INVALID_HID
  *
  *-------------------------------------------------------------------------
  */
 hid_t
-H5VL_register_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t app_ref)
+H5VL_register(H5I_type_t type, const void *object, H5VL_t *vol_driver, hbool_t app_ref)
 {
-    H5VL_object_t  *new_obj     = NULL;
+    H5VL_object_t  *vol_obj     = NULL;
     hid_t           ret_value   = H5I_INVALID_HID;
 
     FUNC_ENTER_NOAPI(H5I_INVALID_HID)
@@ -235,32 +236,135 @@ H5VL_register_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t app_
     HDassert(object);
     HDassert(vol_driver);
 
-    /* setup VOL object */
-    if (NULL == (new_obj = H5FL_CALLOC(H5VL_object_t)))
+    /* Set up VOL object to wrap the passed-in data */
+    if (NULL == (vol_obj = H5FL_CALLOC(H5VL_object_t)))
         HGOTO_ERROR(H5E_VOL, H5E_CANTALLOC, H5I_INVALID_HID, "can't allocate top object structure");
-    new_obj->driver = vol_driver;
-    new_obj->data = object;
+    vol_obj->driver = vol_driver;
+    vol_obj->data = object;
 
     vol_driver->nrefs++;
 
+    /* Datatypes need special handling under the VOL, since they have a non-VOL aspect */
     if (H5I_DATATYPE == type) {
 
         H5T_t *dt = NULL;
 
-        if (NULL == (dt = H5T_construct_datatype(new_obj)))
+        if (NULL == (dt = H5T_construct_datatype(vol_obj)))
             HGOTO_ERROR(H5E_DATATYPE, H5E_CANTINIT, H5I_INVALID_HID, "can't construct datatype object");
 
         if ((ret_value = H5I_register(type, dt, app_ref)) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize handle");
     }
     else {
-        if ((ret_value = H5I_register(type, new_obj, app_ref)) < 0)
+        if ((ret_value = H5I_register(type, vol_obj, app_ref)) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to atomize handle");
     }
 
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL_register_id() */
+} /* end H5VL_register() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL_register_using_existing_id
+ *
+ * Purpose:     Registers an OBJECT in a TYPE with the supplied ID for it.
+ *              This routine will check to ensure the supplied ID is not already
+ *              in use, and ensure that it is a valid ID for the given type, 
+ *              but will NOT check to ensure the OBJECT is not already
+ *              registered (thus, it is possible to register one object under
+ *              multiple IDs).
+ *
+ * NOTE:        Intended for use in refresh calls, where we have to close
+ *              and re-open the underlying data, then hook the VOL object back
+ *              up to the original ID.
+ *
+ * Return:      SUCCEED/FAIL
+ *
+ *-------------------------------------------------------------------------
+ */
+herr_t
+H5VL_register_using_existing_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t app_ref, hid_t existing_id)
+{
+    H5VL_object_t  *new_vol_obj = NULL;     /* Pointer to new VOL object                    */
+    void           *stored_obj = NULL;      /* Pointer to the object that will be stored    */
+    herr_t          ret_value = SUCCEED;    /* Return value                                 */
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    /* Check arguments */
+    HDassert(object);
+    HDassert(vol_driver);
+
+    /* Make sure type number is valid */
+    if(type != H5I_ATTR && type != H5I_DATASET && type != H5I_DATATYPE && type != H5I_FILE && type != H5I_GROUP)
+        HGOTO_ERROR(H5E_ARGS, H5E_BADRANGE, FAIL, "invalid type number")
+
+    /* Set up the new VOL object */
+    if(NULL == (new_vol_obj = H5FL_CALLOC(H5VL_object_t)))
+        HGOTO_ERROR(H5E_VOL, H5E_CANTALLOC, FAIL, "can't allocate memory for VOL object");
+    new_vol_obj->driver = vol_driver;
+    new_vol_obj->data = object;
+
+    /* Bump the reference count on the VOL driver */
+    vol_driver->nrefs++;
+
+    /* If this is a datatype, we have to hide the VOL object under the H5T_t pointer */
+    if(H5I_DATATYPE == type) {
+        if(NULL == (stored_obj = (void *)H5T_construct_datatype(new_vol_obj)))
+            HGOTO_ERROR(H5E_VOL, H5E_CANTINIT, FAIL, "can't construct datatype object");
+    }
+    else
+        stored_obj = (void *)new_vol_obj;
+
+    /* Call the underlying H5I function to complete the registration */
+    if(H5I_register_using_existing_id(type, stored_obj, app_ref, existing_id) < 0)
+        HGOTO_ERROR(H5E_VOL, H5E_CANTREGISTER, FAIL, "can't register object under existing ID")
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_register_using_existing_id() */
+
+
+/*-------------------------------------------------------------------------
+ * Function:	H5VL_register_using_vol_id
+ *
+ * Purpose:     Utility function to create a user ID for an object created
+ *              or opened through the VOL. Uses the VOL driver's ID to
+ *              get the driver information instead of it being passed in.
+ *
+ * Return:      Success:    A valid HDF5 ID
+ *              Failure:    H5I_INVALID_HID 
+ *
+ *-------------------------------------------------------------------------
+ */
+hid_t
+H5VL_register_using_vol_id(H5I_type_t type, const void *obj, hid_t driver_id, hbool_t app_ref)
+{
+    H5VL_class_t    *cls = NULL;
+    H5VL_t          *driver = NULL;       /* VOL driver struct */
+    hid_t           ret_value = H5I_INVALID_HID;
+
+    FUNC_ENTER_NOAPI(FAIL)
+
+    if (NULL == (cls = (H5VL_class_t *)H5I_object_verify(driver_id, H5I_VOL)))
+        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "not a VOL driver ID");
+
+    /* Setup VOL info struct */
+    if (NULL == (driver = H5FL_CALLOC(H5VL_t)))
+        HGOTO_ERROR(H5E_FILE, H5E_NOSPACE, H5I_INVALID_HID, "can't allocate VOL info struct");
+    driver->cls = cls;
+    driver->id = driver_id;
+    if (H5I_inc_ref(driver->id, FALSE) < 0)
+        HGOTO_ERROR(H5E_ATOM, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL driver");
+
+    /* Get an ID for the VOL object */
+    if ((ret_value = H5VL_register(type, obj, driver, app_ref)) < 0)
+        HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register object handle");
+
+done:
+    FUNC_LEAVE_NOAPI(ret_value)
+} /* end H5VL_register_using_vol_id() */
 
 
 /*-------------------------------------------------------------------------
@@ -299,7 +403,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VL_register
+ * Function:    H5VL_register_driver
  *
  * Purpose:     Registers a new VOL driver as a member of the virtual object
  *              layer class.
@@ -312,7 +416,7 @@ done:
  *-------------------------------------------------------------------------
  */
 hid_t
-H5VL_register(const void *_cls, size_t size, hbool_t app_ref)
+H5VL_register_driver(const void *_cls, size_t size, hbool_t app_ref)
 {
     const H5VL_class_t	*cls = (const H5VL_class_t *)_cls;
     H5VL_class_t	*saved = NULL;
@@ -338,47 +442,7 @@ done:
             H5MM_xfree(saved);
 
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL_register() */
-
-
-/*-------------------------------------------------------------------------
- * Function:	H5VL_object_register
- *
- * Purpose:     Utility function to create a user ID for an object created
- *              or opened through the VOL
- *
- * Return:      Success:    A valid HDF5 ID
- *              Failure:    H5I_INVALID_HID 
- *
- *-------------------------------------------------------------------------
- */
-hid_t
-H5VL_object_register(void *obj, H5I_type_t obj_type, hid_t driver_id, hbool_t app_ref)
-{
-    H5VL_class_t    *cls = NULL;
-    H5VL_t          *driver = NULL;       /* VOL driver struct */
-    hid_t           ret_value = H5I_INVALID_HID;
-
-    FUNC_ENTER_NOAPI(FAIL)
-
-    if (NULL == (cls = (H5VL_class_t *)H5I_object_verify(driver_id, H5I_VOL)))
-        HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "not a VOL driver ID");
-
-    /* Setup VOL info struct */
-    if (NULL == (driver = H5FL_CALLOC(H5VL_t)))
-        HGOTO_ERROR(H5E_FILE, H5E_NOSPACE, H5I_INVALID_HID, "can't allocate VOL info struct");
-    driver->cls = cls;
-    driver->id = driver_id;
-    if (H5I_inc_ref(driver->id, FALSE) < 0)
-        HGOTO_ERROR(H5E_ATOM, H5E_CANTINC, H5I_INVALID_HID, "unable to increment ref count on VOL driver");
-
-    /* Get an ID for the VOL object */
-    if ((ret_value = H5VL_register_id(obj_type, obj, driver, app_ref)) < 0)
-        HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to register object handle");
-
-done:
-    FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL_object_register() */
+} /* end H5VL_register_driver() */
 
 
 /*-------------------------------------------------------------------------
@@ -402,7 +466,7 @@ H5VL_get_driver_name(hid_t id, char *name /*out*/, size_t size)
     FUNC_ENTER_NOAPI(FAIL)
 
     /* get the object pointer */
-    if (NULL == (vol_obj = H5VL_get_object(id)))
+    if (NULL == (vol_obj = H5VL_vol_object(id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid file identifier");
 
     cls = vol_obj->driver->cls;
@@ -423,7 +487,7 @@ done:
 
 
 /*-------------------------------------------------------------------------
- * Function:    H5VL_get_object
+ * Function:    H5VL_vol_object
  *
  * Purpose:     Utility function to return the object pointer associated with
  *              a hid_t. This routine is the same as H5I_object for all types
@@ -436,7 +500,7 @@ done:
  *-------------------------------------------------------------------------
  */
 H5VL_object_t *
-H5VL_get_object(hid_t id)
+H5VL_vol_object(hid_t id)
 {
     void            *obj = NULL;
     H5I_type_t      obj_type = H5I_get_type(id);
@@ -463,7 +527,7 @@ H5VL_get_object(hid_t id)
     ret_value = (H5VL_object_t *)obj;
 done:
     FUNC_LEAVE_NOAPI(ret_value)
-} /* end H5VL_get_object() */
+} /* end H5VL_vol_object() */
 
 
 /*-------------------------------------------------------------------------
@@ -597,15 +661,27 @@ done:
     FUNC_LEAVE_NOAPI(ret_value)
 } /* end H5VL_object_verify() */
 
-
-/* XXX (VOL MERGE): This could be a macro like in H5F */
+
+/*-------------------------------------------------------------------------
+ * Function:    H5VL_driver_data
+ *
+ * Purpose:     Get the VOL-specific data stored in a VOL object
+ *
+ * Return:      Success:    Pointer to the data
+ *
+ *              Failure:    NULL (technically can't fail)
+ *
+ *-------------------------------------------------------------------------
+ */
 void *
-H5VL_driver_object(H5VL_object_t *vol_obj)
+H5VL_driver_data(H5VL_object_t *vol_obj)
 {
     FUNC_ENTER_NOAPI_NOINIT_NOERR
 
+    HDassert(vol_obj);
+
     FUNC_LEAVE_NOAPI(vol_obj->data)
-} /* end H5VL_driver_object() */
+} /* end H5VL_driver_data() */
 
 
 /*-------------------------------------------------------------------------
diff --git a/src/H5VLnative.c b/src/H5VLnative.c
index acfceed..acd56cd 100644
--- a/src/H5VLnative.c
+++ b/src/H5VLnative.c
@@ -215,7 +215,7 @@ H5VL_native_init(void)
 
     /* Register the native VOL driver, if it isn't already */
     if(NULL == H5I_object_verify(H5VL_NATIVE_ID_g, H5I_VOL)) {
-        if((H5VL_NATIVE_ID_g = H5VL_register((const H5VL_class_t *)&H5VL_native_cls_g, 
+        if((H5VL_NATIVE_ID_g = H5VL_register_driver((const H5VL_class_t *)&H5VL_native_cls_g, 
                                           sizeof(H5VL_class_t), TRUE)) < 0)
             HGOTO_ERROR(H5E_ATOM, H5E_CANTINSERT, H5I_INVALID_HID, "can't create ID for native VOL driver")
     }
@@ -379,7 +379,7 @@ done:
  *---------------------------------------------------------------------------
  */
 hid_t
-H5VL_native_register(H5I_type_t type, void *obj, hbool_t app_ref)
+H5VL_native_register(H5I_type_t type, const void *obj, hbool_t app_ref)
 {
     hid_t    ret_value = H5I_INVALID_HID;
 
@@ -395,7 +395,7 @@ H5VL_native_register(H5I_type_t type, void *obj, hbool_t app_ref)
             HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, H5I_INVALID_HID, "can only get an ID for an uncommitted datatype")
 
     /* Get an ID for the object */
-    if((ret_value = H5VL_object_register(obj, type, H5VL_NATIVE_ID_g, app_ref)) < 0)
+    if((ret_value = H5VL_register_using_vol_id(type, obj, H5VL_NATIVE_ID_g, app_ref)) < 0)
         HGOTO_ERROR(H5E_ATOM, H5E_CANTREGISTER, H5I_INVALID_HID, "unable to get an ID for the object")
 
 done:
@@ -422,7 +422,7 @@ H5VL_native_unregister(hid_t obj_id)
     FUNC_ENTER_NOAPI_NOINIT
 
     /* get the driver pointer */
-    if(NULL == (vol_obj = (H5VL_object_t *)H5VL_get_object(obj_id)))
+    if(NULL == (vol_obj = (H5VL_object_t *)H5VL_vol_object(obj_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "invalid ID")
 
     /* free object */
diff --git a/src/H5VLnative.h b/src/H5VLnative.h
index 4e33e8a..19b9ff9 100644
--- a/src/H5VLnative.h
+++ b/src/H5VLnative.h
@@ -34,7 +34,7 @@ extern "C" {
 H5_DLL herr_t H5Pset_fapl_native(hid_t fapl_id);
 H5_DLL hid_t H5VL_native_get_driver_id(void);
 H5_DLL hid_t H5VL_native_init(void);
-H5_DLL hid_t H5VL_native_register(H5I_type_t type, void *obj, hbool_t app_ref);
+H5_DLL hid_t H5VL_native_register(H5I_type_t type, const void *obj, hbool_t app_ref);
 H5_DLL herr_t H5VL_native_unregister(hid_t obj_id);
 
 #ifdef __cplusplus
diff --git a/src/H5VLprivate.h b/src/H5VLprivate.h
index 98be308..003e6f5 100644
--- a/src/H5VLprivate.h
+++ b/src/H5VLprivate.h
@@ -53,17 +53,34 @@ typedef struct H5VL_driver_prop_t {
 /* Library Private Prototypes */
 /******************************/
 
-/* Common functions */
+/* Utility functions */
 H5_DLL herr_t H5VL_init(void);
-H5_DLL hid_t H5VL_register_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t app_ref);
-H5_DLL herr_t H5VL_free_object(H5VL_object_t *obj);
-H5_DLL hid_t H5VL_register(const void *cls, size_t size, hbool_t app_ref);
-H5_DLL hid_t H5VL_object_register(void *obj, H5I_type_t obj_type, hid_t driver_id, hbool_t app_ref);
+
+/* Functions that deal with VOL drivers */
+H5_DLL hid_t H5VL_register_driver(const void *cls, size_t size, hbool_t app_ref);
 H5_DLL ssize_t H5VL_get_driver_name(hid_t id, char *name/*out*/, size_t size);
-H5_DLL H5VL_object_t *H5VL_get_object(hid_t id);
+
+/* NOTE:    The object and ID functions below deal in VOL objects (i.e.;
+ *          H5VL_object_t). Similar non-VOL calls exist in H5Iprivate.h. Use
+ *          the H5VL calls with objects that go through the VOL, such as
+ *          datasets and groups, and the H5I calls with objects
+ *          that do not, such as property lists and dataspaces. Datatypes
+ *          are can be either named, where they will use the VOL, or not,
+ *          and thus require special treatment. See the datatype docs for
+ *          how to handle this.
+ */
+
+/* Functions that manipulate VOL objects */
 H5_DLL void *H5VL_object(hid_t id);
 H5_DLL void *H5VL_object_verify(hid_t id, H5I_type_t obj_type);
-H5_DLL void *H5VL_driver_object(H5VL_object_t *obj);
+H5_DLL void *H5VL_driver_data(H5VL_object_t *obj);
+H5_DLL H5VL_object_t *H5VL_vol_object(hid_t id);
+H5_DLL herr_t H5VL_free_object(H5VL_object_t *obj);
+
+/* ID registration functions */
+H5_DLL hid_t H5VL_register(H5I_type_t type, const void *object, H5VL_t *vol_driver, hbool_t app_ref);
+H5_DLL hid_t H5VL_register_using_vol_id(H5I_type_t type, const void *obj, hid_t driver_id, hbool_t app_ref);
+H5_DLL herr_t H5VL_register_using_existing_id(H5I_type_t type, void *object, H5VL_t *vol_driver, hbool_t app_ref, hid_t existing_id);
 
 /* Attribute functions */
 H5_DLL void *H5VL_attr_create(void *obj, H5VL_loc_params_t loc_params, const H5VL_class_t *cls, const char *attr_name, hid_t acpl_id, hid_t aapl_id, hid_t dxpl_id, void **req);
diff --git a/src/H5VLpublic.h b/src/H5VLpublic.h
index d118bcc..600de0d 100644
--- a/src/H5VLpublic.h
+++ b/src/H5VLpublic.h
@@ -411,13 +411,13 @@ extern "C" {
 H5_DLL herr_t H5VLinitialize(hid_t driver_id, hid_t vipl_id);
 H5_DLL herr_t H5VLterminate(hid_t driver_id, hid_t vtpl_id);
 H5_DLL herr_t H5VLclose(hid_t driver_id);
-H5_DLL hid_t H5VLregister(const H5VL_class_t *cls);
-H5_DLL hid_t H5VLregister_by_name(const char *driver_name);
-H5_DLL herr_t H5VLunregister(hid_t driver_id);
-H5_DLL htri_t H5VLis_registered(const char *name);
+H5_DLL hid_t H5VLregister_driver(const H5VL_class_t *cls);
+H5_DLL hid_t H5VLregister_driver_by_name(const char *driver_name);
+H5_DLL herr_t H5VLunregister_driver(hid_t driver_id);
+H5_DLL htri_t H5VLis_driver_registered(const char *name);
 H5_DLL hid_t H5VLget_driver_id(const char *name);
 H5_DLL ssize_t H5VLget_driver_name(hid_t id, char *name/*out*/, size_t size);
-H5_DLL hid_t H5VLobject_register(void *obj, H5I_type_t obj_type, hid_t driver_id);
+H5_DLL hid_t H5VLregister(H5I_type_t obj_type, const void *obj, hid_t driver_id);
 H5_DLL void *H5VLobject(hid_t id);
 H5_DLL herr_t H5VLget_object(hid_t obj_id, void **obj);