Bring fix for HDFFV-9697 from develop branch.

Populate the fix for HDFFV-9697: Fix for unknown message from develop branch.
Tested on ostrich, platypus, kite, quail, osx1010test, emu, mayll, moohan, kituo.

11 files changed, 503 insertions, 268 deletions

diff --git a/src/H5Dint.c b/src/H5Dint.c
index 16ced02..b5adfc4 100644
--- a/src/H5Dint.c
+++ b/src/H5Dint.c
@@ -869,16 +869,22 @@ H5D__update_oh_info(H5F_t *file, hid_t dxpl_id, H5D_t *dset, hid_t dapl_id)
     if(NULL == (dc_plist = (H5P_genplist_t *)H5I_object(dset->shared->dcpl_id)))
         HGOTO_ERROR(H5E_ARGS, H5E_BADTYPE, FAIL, "can't get dataset creation property list")
 
-    /* Check whether to add a "bogus" message */
-    if(H5P_exist_plist(dc_plist, H5O_BOGUS_MSG_FLAGS_NAME) > 0) {
+     /* Check whether to add a "bogus" message */
+    if( (H5P_exist_plist(dc_plist, H5O_BOGUS_MSG_FLAGS_NAME) > 0) &&
+        (H5P_exist_plist(dc_plist, H5O_BOGUS_MSG_ID_NAME) > 0) ) {
+
         uint8_t bogus_flags = 0;        /* Flags for creating "bogus" message */
+        unsigned bogus_id;              /* "bogus" ID */
 
+         /* Retrieve "bogus" message ID */
+        if(H5P_get(dc_plist, H5O_BOGUS_MSG_ID_NAME, &bogus_id) < 0)
+            HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get bogus ID options")
         /* Retrieve "bogus" message flags */
         if(H5P_get(dc_plist, H5O_BOGUS_MSG_FLAGS_NAME, &bogus_flags) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTGET, FAIL, "can't get bogus message options")
 
         /* Add a "bogus" message (for error testing). */
-        if(H5O_bogus_oh(file, dxpl_id, oh, (unsigned)bogus_flags) < 0)
+        if(H5O_bogus_oh(file, dxpl_id, oh, bogus_id, (unsigned)bogus_flags) < 0)
             HGOTO_ERROR(H5E_DATASET, H5E_CANTINIT, FAIL, "unable to create 'bogus' message")
     } /* end if */
 }
diff --git a/src/H5Fpkg.h b/src/H5Fpkg.h
index 21034d7..3a343cc 100644
--- a/src/H5Fpkg.h
+++ b/src/H5Fpkg.h
@@ -310,7 +310,7 @@ H5_DLL herr_t H5F_super_free(H5F_super_t *sblock);
 
 /* Superblock extension related routines */
 H5_DLL herr_t H5F_super_ext_open(H5F_t *f, haddr_t ext_addr, H5O_loc_t *ext_ptr);
-H5_DLL herr_t H5F_super_ext_write_msg(H5F_t *f, hid_t dxpl_id, void *mesg, unsigned id, hbool_t may_create);
+H5_DLL herr_t H5F_super_ext_write_msg(H5F_t *f, hid_t dxpl_id, unsigned id, void *mesg, hbool_t may_create);
 H5_DLL herr_t H5F_super_ext_close(H5F_t *f, H5O_loc_t *ext_ptr, hid_t dxpl_id,
     hbool_t was_created);
 
diff --git a/src/H5Fsuper.c b/src/H5Fsuper.c
index 3f2b33f..5f71f61 100644
--- a/src/H5Fsuper.c
+++ b/src/H5Fsuper.c
@@ -712,7 +712,7 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5F_super_ext_write_msg(H5F_t *f, hid_t dxpl_id, void *mesg, unsigned id, hbool_t may_create)
+H5F_super_ext_write_msg(H5F_t *f, hid_t dxpl_id, unsigned id, void *mesg, hbool_t may_create)
 {
     hbool_t     ext_created = FALSE;   /* Whether superblock extension was created */
     hbool_t     ext_opened = FALSE;    /* Whether superblock extension was opened */
diff --git a/src/H5O.c b/src/H5O.c
index 38d9f6b..8c2d08d 100644
--- a/src/H5O.c
+++ b/src/H5O.c
@@ -98,34 +98,39 @@ static const H5O_obj_class_t *H5O_obj_class_real(H5O_t *oh);
  */
 
 const H5O_msg_class_t *const H5O_msg_class_g[] = {
-    H5O_MSG_NULL,		/*0x0000 Null				*/
-    H5O_MSG_SDSPACE,		/*0x0001 Dataspace			*/
-    H5O_MSG_LINFO,		/*0x0002 Link information		*/
-    H5O_MSG_DTYPE,		/*0x0003 Datatype			*/
-    H5O_MSG_FILL,       	/*0x0004 Old data storage -- fill value */
-    H5O_MSG_FILL_NEW,		/*0x0005 New data storage -- fill value */
-    H5O_MSG_LINK,		/*0x0006 Link 				*/
-    H5O_MSG_EFL,		/*0x0007 Data storage -- external data files */
-    H5O_MSG_LAYOUT,		/*0x0008 Data Layout			*/
+    H5O_MSG_NULL,           /*0x0000 Null                                   */
+    H5O_MSG_SDSPACE,        /*0x0001 Dataspace                              */
+    H5O_MSG_LINFO,          /*0x0002 Link information                       */
+    H5O_MSG_DTYPE,          /*0x0003 Datatype                               */
+    H5O_MSG_FILL,           /*0x0004 Old data storage -- fill value         */
+    H5O_MSG_FILL_NEW,       /*0x0005 New data storage -- fill value         */
+    H5O_MSG_LINK,           /*0x0006 Link                                   */
+    H5O_MSG_EFL,            /*0x0007 Data storage -- external data files    */
+    H5O_MSG_LAYOUT,         /*0x0008 Data Layout                            */
 #ifdef H5O_ENABLE_BOGUS
-    H5O_MSG_BOGUS,		/*0x0009 "Bogus" (for testing)		*/
+    H5O_MSG_BOGUS_VALID,    /*0x0009 "Bogus valid" (for testing)            */
 #else /* H5O_ENABLE_BOGUS */
-    NULL,			/*0x0009 "Bogus" (for testing)		*/
+    NULL,                   /*0x0009 "Bogus valid" (for testing)            */
+#endif /* H5O_ENABLE_BOGUS */
+    H5O_MSG_GINFO,          /*0x000A Group information                      */
+    H5O_MSG_PLINE,          /*0x000B Data storage -- filter pipeline        */
+    H5O_MSG_ATTR,           /*0x000C Attribute                              */
+    H5O_MSG_NAME,           /*0x000D Object name                            */
+    H5O_MSG_MTIME,          /*0x000E Object modification date and time      */
+    H5O_MSG_SHMESG,         /*0x000F File-wide shared message table         */
+    H5O_MSG_CONT,           /*0x0010 Object header continuation             */
+    H5O_MSG_STAB,           /*0x0011 Symbol table                           */
+    H5O_MSG_MTIME_NEW,      /*0x0012 New Object modification date and time  */
+    H5O_MSG_BTREEK,         /*0x0013 Non-default v1 B-tree 'K' values       */
+    H5O_MSG_DRVINFO,        /*0x0014 Driver info settings                   */
+    H5O_MSG_AINFO,          /*0x0015 Attribute information                  */
+    H5O_MSG_REFCOUNT,       /*0x0016 Object's ref. count                    */
+    H5O_MSG_UNKNOWN,        /*0x0017 Placeholder for unknown message        */
+#ifdef H5O_ENABLE_BOGUS
+    H5O_MSG_BOGUS_INVALID   /*0x0018 "Bogus invalid" (for testing)          */
+#else /* H5O_ENABLE_BOGUS */
+    NULL                    /*0x0018 "Bogus invalid" (for testing)          */
 #endif /* H5O_ENABLE_BOGUS */
-    H5O_MSG_GINFO,		/*0x000A Group information		*/
-    H5O_MSG_PLINE,		/*0x000B Data storage -- filter pipeline */
-    H5O_MSG_ATTR,		/*0x000C Attribute			*/
-    H5O_MSG_NAME,		/*0x000D Object name			*/
-    H5O_MSG_MTIME,		/*0x000E Object modification date and time */
-    H5O_MSG_SHMESG,		/*0x000F File-wide shared message table */
-    H5O_MSG_CONT,		/*0x0010 Object header continuation	*/
-    H5O_MSG_STAB,		/*0x0011 Symbol table			*/
-    H5O_MSG_MTIME_NEW,		/*0x0012 New Object modification date and time */
-    H5O_MSG_BTREEK,		/*0x0013 Non-default v1 B-tree 'K' values */
-    H5O_MSG_DRVINFO,		/*0x0014 Driver info settings		*/
-    H5O_MSG_AINFO,		/*0x0015 Attribute information		*/
-    H5O_MSG_REFCOUNT,		/*0x0016 Object's ref. count		*/
-    H5O_MSG_UNKNOWN		/*0x0017 Placeholder for unknown message */
 };
 
 /* Declare a free list to manage the H5O_t struct */
@@ -2122,10 +2127,11 @@ done:
  *-------------------------------------------------------------------------
  */
 herr_t
-H5O_bogus_oh(H5F_t *f, hid_t dxpl_id, H5O_t *oh, unsigned mesg_flags)
+H5O_bogus_oh(H5F_t *f, hid_t dxpl_id, H5O_t *oh, unsigned bogus_id, unsigned mesg_flags)
 {
-    size_t	idx;                /* Local index variable */
-    herr_t ret_value = SUCCEED;     /* Return value */
+    size_t idx;                 /* Local index variable */
+    H5O_msg_class_t *type;      /* Message class type */
+    herr_t ret_value = SUCCEED; /* Return value */
 
     FUNC_ENTER_NOAPI(FAIL)
 
@@ -2134,7 +2140,8 @@ H5O_bogus_oh(H5F_t *f, hid_t dxpl_id, H5O_t *oh, unsigned mesg_flags)
 
     /* Look for existing message */
     for(idx = 0; idx < oh->nmesgs; idx++)
-	if(H5O_MSG_BOGUS == oh->mesg[idx].type)
+        if(H5O_MSG_BOGUS_VALID == oh->mesg[idx].type ||
+           H5O_MSG_BOGUS_INVALID == oh->mesg[idx].type)
             break;
 
     /* Create a new message */
@@ -2142,18 +2149,25 @@ H5O_bogus_oh(H5F_t *f, hid_t dxpl_id, H5O_t *oh, unsigned mesg_flags)
         H5O_bogus_t *bogus;             /* Pointer to the bogus information */
 
         /* Allocate the native message in memory */
-	if(NULL == (bogus = H5MM_malloc(sizeof(H5O_bogus_t))))
-	    HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "memory allocation failed for 'bogus' message")
+        if(NULL == (bogus = H5MM_malloc(sizeof(H5O_bogus_t))))
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "memory allocation failed for 'bogus' message")
 
         /* Update the native value */
         bogus->u = H5O_BOGUS_VALUE;
 
+        if(bogus_id == H5O_BOGUS_VALID_ID)
+            type = H5O_MSG_BOGUS_VALID;
+        else if(bogus_id == H5O_BOGUS_INVALID_ID)
+            type = H5O_MSG_BOGUS_INVALID;
+        else
+            HGOTO_ERROR(H5E_ATOM, H5E_BADATOM, FAIL, "invalid ID for 'bogus' message")
+
         /* Allocate space in the object header for bogus message */
-	if(H5O_msg_alloc(f, dxpl_id, oh, H5O_MSG_BOGUS, &mesg_flags, bogus, &idx) < 0)
-	    HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to allocate space for 'bogus' message")
+        if(H5O_msg_alloc(f, dxpl_id, oh, type, &mesg_flags, bogus, &idx) < 0)
+            HGOTO_ERROR(H5E_OHDR, H5E_CANTINIT, FAIL, "unable to allocate space for 'bogus' message")
 
         /* Point to "bogus" information (take it over) */
-	oh->mesg[idx].native = bogus;
+        oh->mesg[idx].native = bogus;
 
         /* Set the appropriate flags for the message */
         oh->mesg[idx].flags = mesg_flags;
diff --git a/src/H5Obogus.c b/src/H5Obogus.c
index b368ab6..3effae3 100644
--- a/src/H5Obogus.c
+++ b/src/H5Obogus.c
@@ -46,27 +46,51 @@ static herr_t H5O_bogus_debug(H5F_t *f, hid_t dxpl_id, const void *_mesg, FILE *
 			     int indent, int fwidth);
 
 /* This message derives from H5O message class */
-const H5O_msg_class_t H5O_MSG_BOGUS[1] = {{
-    H5O_BOGUS_ID,            	/*message id number             */
-    "bogus",                 	/*message name for debugging    */
-    0,     	                /*native message size           */
-    0,				/* messages are sharable?       */
-    H5O_bogus_decode,        	/*decode message                */
-    H5O_bogus_encode,        	/*encode message                */
-    NULL,          	        /*copy the native value         */
-    H5O_bogus_size,          	/*raw message size              */
-    NULL,         	        /*free internal memory          */
-    NULL,		        /*free method			*/
-    NULL,		        /* file delete method		*/
-    NULL,			/* link method			*/
-    NULL,			/*set share method		*/
-    NULL,		    	/*can share method		*/
-    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             */
+const H5O_msg_class_t H5O_MSG_BOGUS_VALID[1] = {{
+    H5O_BOGUS_VALID_ID,     /*message id number                 */
+    "bogus valid",          /*message name for debugging        */
+    0,                      /*native message size               */
+    0,                      /*messages are sharable?            */
+    H5O_bogus_decode,       /*decode message                    */
+    H5O_bogus_encode,       /*encode message                    */
+    NULL,                   /*copy the native value             */
+    H5O_bogus_size,         /*raw message size                  */
+    NULL,                   /*free internal memory              */
+    NULL,                   /*free method                       */
+    NULL,                   /* file delete method               */
+    NULL,                   /* link method                      */
+    NULL,                   /*set share method                  */
+    NULL,                   /*can share method                  */
+    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                 */
+}};
+
+/* This message derives from H5O message class */
+const H5O_msg_class_t H5O_MSG_BOGUS_INVALID[1] = {{
+    H5O_BOGUS_INVALID_ID,   /*message id number                 */
+    "bogus invalid",        /*message name for debugging        */
+    0,                      /*native message size               */
+    0,                      /*messages are sharable?            */
+    H5O_bogus_decode,       /*decode message                    */
+    H5O_bogus_encode,       /*encode message                    */
+    NULL,                   /*copy the native value             */
+    H5O_bogus_size,         /*raw message size                  */
+    NULL,                   /*free internal memory              */
+    NULL,                   /*free method                       */
+    NULL,                   /* file delete method               */
+    NULL,                   /* link method                      */
+    NULL,                   /*set share method                  */
+    NULL,                   /*can share method                  */
+    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 2aaf933..0f22acb 100644
--- a/src/H5Ocache.c
+++ b/src/H5Ocache.c
@@ -1116,10 +1116,6 @@ H5O_chunk_deserialize(H5O_t *oh, haddr_t addr, size_t len, const uint8_t *image,
         else
             id = *p++;
 
-        /* Check for unknown message ID getting encoded in file */
-        if(id == H5O_UNKNOWN_ID)
-            HGOTO_ERROR(H5E_OHDR, H5E_CANTLOAD, FAIL, "'unknown' message ID encoded in file?!?")
-
         /* Message size */
         UINT16DECODE(p, mesg_size);
         HDassert(mesg_size == H5O_ALIGN_OH(oh, mesg_size));
@@ -1193,7 +1189,12 @@ H5O_chunk_deserialize(H5O_t *oh, haddr_t addr, size_t len, const uint8_t *image,
 
             /* Point unknown messages at 'unknown' message class */
             /* (Usually from future versions of the library) */
-            if(id >= NELMTS(H5O_msg_class_g) || NULL == H5O_msg_class_g[id]) {
+            if(id >= H5O_UNKNOWN_ID ||
+#ifdef H5O_ENABLE_BOGUS
+               id == H5O_BOGUS_VALID_ID ||
+#endif
+               NULL == H5O_msg_class_g[id]) {
+
                 H5O_unknown_t *unknown;     /* Pointer to "unknown" message info */
 
                 /* Allocate "unknown" message info */
diff --git a/src/H5Opkg.h b/src/H5Opkg.h
index 2c8c5a0..c7789fe 100644
--- a/src/H5Opkg.h
+++ b/src/H5Opkg.h
@@ -31,7 +31,7 @@
 #define H5O_NMESGS	8 		/*initial number of messages	     */
 #define H5O_NCHUNKS	2		/*initial number of chunks	     */
 #define H5O_MIN_SIZE	22		/* Min. obj header data size (must be big enough for a message prefix and a continuation message) */
-#define H5O_MSG_TYPES   24              /* # of types of messages            */
+#define H5O_MSG_TYPES   25              /* # of types of messages            */
 #define H5O_MAX_CRT_ORDER_IDX 65535     /* Max. creation order index value   */
 
 /* Versions of object header structure */
@@ -441,11 +441,13 @@ H5_DLLVAR const H5O_msg_class_t H5O_MSG_EFL[1];
 H5_DLLVAR const H5O_msg_class_t H5O_MSG_LAYOUT[1];
 
 #ifdef H5O_ENABLE_BOGUS
-/* "Bogus" Message. (0x0009) */
+/* "Bogus valid" Message. (0x0009) */
+/* "Bogus invalid" Message. (0x00018) */
 /*
  * Used for debugging - should never be found in valid HDF5 file.
  */
-H5_DLLVAR const H5O_msg_class_t H5O_MSG_BOGUS[1];
+H5_DLLVAR const H5O_msg_class_t H5O_MSG_BOGUS_VALID[1];
+H5_DLLVAR const H5O_msg_class_t H5O_MSG_BOGUS_INVALID[1];
 #endif /* H5O_ENABLE_BOGUS */
 
 /* Group Information Message. (0x000a) */
diff --git a/src/H5Oprivate.h b/src/H5Oprivate.h
index 94ba6a0..e749398 100644
--- a/src/H5Oprivate.h
+++ b/src/H5Oprivate.h
@@ -83,6 +83,9 @@ typedef struct H5O_t H5O_t;
 /* Hash value constants */
 #define H5O_HASH_SIZE 32
 
+/* Enable reading/writing "bogus" messages */
+/* #define H5O_ENABLE_BOGUS */
+
 /* ========= Object Creation properties ============ */
 #define H5O_CRT_ATTR_MAX_COMPACT_NAME	"max compact attr"      /* Max. # of attributes to store compactly */
 #define H5O_CRT_ATTR_MIN_DENSE_NAME	"min dense attr"	/* Min. # of attributes to store densely */
@@ -92,6 +95,11 @@ typedef struct H5O_t H5O_t;
 #ifdef H5O_ENABLE_BOGUS
 #define H5O_BOGUS_MSG_FLAGS_NAME        "bogus msg flags"       /* Flags for 'bogus' message */
 #define H5O_BOGUS_MSG_FLAGS_SIZE        sizeof(uint8_t)
+
+/* bogus ID can be either (a) H5O_BOGUS_VALID_ID or (b) H5O_BOGUS_INVALID_ID */
+#define H5O_BOGUS_MSG_ID_NAME        "bogus msg id"         /* ID for 'bogus' message */
+#define H5O_BOGUS_MSG_ID_SIZE        sizeof(unsigned)
+
 #endif /* H5O_ENABLE_BOGUS */
 #ifdef H5O_ENABLE_BAD_MESG_COUNT
 #define H5O_BAD_MESG_COUNT_NAME         "bad message count"       /* Flag setting bad message count */
@@ -168,32 +176,41 @@ typedef struct H5O_copy_t {
 } H5O_copy_t;
 
 /* Header message IDs */
-#define H5O_NULL_ID	0x0000          /* Null Message.  */
-#define H5O_SDSPACE_ID	0x0001          /* Dataspace Message. */
-#define H5O_LINFO_ID    0x0002          /* Link info Message. */
-#define H5O_DTYPE_ID	0x0003          /* Datatype Message.  */
-#define H5O_FILL_ID     0x0004          /* Fill Value Message. (Old)  */
-#define H5O_FILL_NEW_ID 0x0005          /* Fill Value Message. (New)  */
-#define H5O_LINK_ID     0x0006          /* Link Message. */
-#define H5O_EFL_ID	0x0007          /* External File List Message  */
-#define H5O_LAYOUT_ID	0x0008          /* Data Layout Message.  */
-#define H5O_BOGUS_ID	0x0009          /* "Bogus" Message.  */
-#define H5O_GINFO_ID	0x000a          /* Group info Message.  */
-#define H5O_PLINE_ID	0x000b          /* Filter pipeline message.  */
-#define H5O_ATTR_ID	0x000c          /* Attribute Message.  */
-#define H5O_NAME_ID	0x000d          /* Object name message.  */
-#define H5O_MTIME_ID	0x000e          /* Modification time message. (Old)  */
-#define H5O_SHMESG_ID   0x000f          /* Shared message "SOHM" table. */
-#define H5O_CONT_ID	0x0010          /* Object header continuation message.  */
-#define H5O_STAB_ID	0x0011          /* Symbol table message.  */
-#define H5O_MTIME_NEW_ID 0x0012         /* Modification time message. (New)  */
-#define H5O_BTREEK_ID   0x0013          /* v1 B-tree 'K' values message.  */
-#define H5O_DRVINFO_ID  0x0014          /* Driver info message.  */
-#define H5O_AINFO_ID    0x0015          /* Attribute info message.  */
-#define H5O_REFCOUNT_ID 0x0016          /* Reference count message.  */
-#define H5O_UNKNOWN_ID  0x0017          /* Placeholder message ID for unknown message.  */
+#define H5O_NULL_ID             0x0000  /* Null Message.  */
+#define H5O_SDSPACE_ID          0x0001  /* Dataspace Message. */
+#define H5O_LINFO_ID            0x0002  /* Link info Message. */
+#define H5O_DTYPE_ID            0x0003  /* Datatype Message.  */
+#define H5O_FILL_ID             0x0004  /* Fill Value Message. (Old)  */
+#define H5O_FILL_NEW_ID         0x0005  /* Fill Value Message. (New)  */
+#define H5O_LINK_ID             0x0006  /* Link Message. */
+#define H5O_EFL_ID              0x0007  /* External File List Message  */
+#define H5O_LAYOUT_ID           0x0008  /* Data Layout Message.  */
+#define H5O_BOGUS_VALID_ID      0x0009  /* "Bogus valid" Message.  */
+#define H5O_GINFO_ID            0x000a  /* Group info Message.  */
+#define H5O_PLINE_ID            0x000b  /* Filter pipeline message.  */
+#define H5O_ATTR_ID             0x000c  /* Attribute Message.  */
+#define H5O_NAME_ID             0x000d  /* Object name message.  */
+#define H5O_MTIME_ID            0x000e  /* Modification time message. (Old)  */
+#define H5O_SHMESG_ID           0x000f  /* Shared message "SOHM" table. */
+#define H5O_CONT_ID             0x0010  /* Object header continuation message.  */
+#define H5O_STAB_ID             0x0011  /* Symbol table message.  */
+#define H5O_MTIME_NEW_ID        0x0012  /* Modification time message. (New)  */
+#define H5O_BTREEK_ID           0x0013  /* v1 B-tree 'K' values message.  */
+#define H5O_DRVINFO_ID          0x0014  /* Driver info message.  */
+#define H5O_AINFO_ID            0x0015  /* Attribute info message.  */
+#define H5O_REFCOUNT_ID         0x0016  /* Reference count message.  */
+#define H5O_UNKNOWN_ID          0x0017  /* Placeholder message ID for unknown message.  */
                                         /* (this should never exist in a file) */
 
+/*
+ * Note: Must increment H5O_MSG_TYPES in H5Opkg.h and update H5O_msg_class_g
+ *      in H5O.c when creating a new message type.  Also bump the value of
+ *      H5O_BOGUS_INVALID_ID, below, to be one greater than the value of
+ *      H5O_UNKNOWN_ID.
+ *
+ * (this should never exist in a file)
+ */
+#define H5O_BOGUS_INVALID_ID    0x0018  /* "Bogus invalid" Message.  */
 
 /* Shared object message types.
  * Shared objects can be committed, in which case the shared message contains
@@ -425,9 +442,6 @@ typedef struct H5O_layout_t {
     H5O_storage_t storage;              /* Information for storing dataset elements */
 } H5O_layout_t;
 
-/* Enable reading/writing "bogus" messages */
-/* #define H5O_ENABLE_BOGUS */
-
 #ifdef H5O_ENABLE_BOGUS
 /*
  * "Bogus" Message.
@@ -641,7 +655,7 @@ H5_DLL herr_t H5O_touch(const H5O_loc_t *loc, hbool_t force, hid_t dxpl_id);
 H5_DLL herr_t H5O_touch_oh(H5F_t *f, hid_t dxpl_id, H5O_t *oh,
     hbool_t force);
 #ifdef H5O_ENABLE_BOGUS
-H5_DLL herr_t H5O_bogus_oh(H5F_t *f, hid_t dxpl_id, H5O_t *oh, unsigned mesg_flags);
+H5_DLL herr_t H5O_bogus_oh(H5F_t *f, hid_t dxpl_id, H5O_t *oh, unsigned mesg_id, unsigned mesg_flags);
 #endif /* H5O_ENABLE_BOGUS */
 H5_DLL herr_t H5O_delete(H5F_t *f, hid_t dxpl_id, haddr_t addr);
 H5_DLL herr_t H5O_get_hdr_info(const H5O_loc_t *oloc, hid_t dxpl_id, H5O_hdr_info_t *hdr);
diff --git a/test/gen_bogus.c b/test/gen_bogus.c
index df1e81f..290ec08 100644
--- a/test/gen_bogus.c
+++ b/test/gen_bogus.c
@@ -36,18 +36,21 @@
 #define FALSE 0
 #endif /* FALSE */
 
-int main(void)
-{
 #ifdef H5O_ENABLE_BOGUS
-    hid_t fid = -1;             /* File ID */
+
+/*
+ * Create datasets in the location (in "/" or "/group") with 
+ *   message id: (a) H5O_BOGUS_VALID_ID or (b)H5O_BOGUS_INVALID_ID
+ *   and various unknown message flags
+ */
+static int
+generate_datasets(hid_t loc_id, unsigned bogus_id) 
+{
     hid_t sid = -1;             /* Dataspace ID */
     hid_t dcpl = -1;            /* Dataset creation property list ID */
     hid_t did = -1;             /* Dataset ID */
     uint8_t bogus_flags = 0;    /* Flags for bogus message */
 
-    /* Create file for test datasets */
-    if((fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT)) < 0) goto error;
-
     /* Create dataspace for datasets */
     if((sid = H5Screate(H5S_SCALAR)) < 0) goto error;
 
@@ -57,24 +60,30 @@ int main(void)
     /* Add property for bogus message flags */
     if(H5Pinsert2(dcpl, H5O_BOGUS_MSG_FLAGS_NAME, H5O_BOGUS_MSG_FLAGS_SIZE, &bogus_flags, NULL, NULL, NULL, NULL, NULL, NULL) < 0) goto error;
 
+    /* Add property for bogus message ID */
+    if(H5Pinsert2(dcpl, H5O_BOGUS_MSG_ID_NAME, H5O_BOGUS_MSG_ID_SIZE, &bogus_id, NULL, NULL, NULL, NULL, NULL, NULL) < 0) goto error;
+
     /* Create dataset with "bogus" message, but no message flags */
-    if((did = H5Dcreate2(fid, "/Dataset1", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT)) < 0) goto error;
+    if((did = H5Dcreate2(loc_id, "Dataset1", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT)) < 0) goto error;
     if(H5Dclose(did) < 0) goto error;
 
-    /* Set "fail if unknown" message flag for bogus message */
+    /* Set "fail if unknown and open for write" message flag for bogus message */
     bogus_flags = H5O_MSG_FLAG_FAIL_IF_UNKNOWN_AND_OPEN_FOR_WRITE;
     if(H5Pset(dcpl, H5O_BOGUS_MSG_FLAGS_NAME, &bogus_flags) < 0) goto error;
 
     /* Create second dataset, with "fail if unknown" message flag */
-    if((did = H5Dcreate2(fid, "/Dataset2", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT)) < 0) goto error;
+    if((did = H5Dcreate2(loc_id, "Dataset2", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT)) < 0) goto error;
     if(H5Dclose(did) < 0) goto error;
 
+    /* Set "fail if unknown always" message flag for bogus message */
+    /* There is no H5O_MSG_FLAG_FAIL_IF_UNKNOWN_ALWAYS, skip creating "Dataset3" */
+
     /* Set "mark if unknown" message flag for bogus message */
     bogus_flags = H5O_MSG_FLAG_MARK_IF_UNKNOWN;
     if(H5Pset(dcpl, H5O_BOGUS_MSG_FLAGS_NAME, &bogus_flags) < 0) goto error;
 
-    /* Create second dataset, with "mark if unknown" message flag */
-    if((did = H5Dcreate2(fid, "/Dataset3", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT)) < 0) goto error;
+    /* Create fourth dataset, with "mark if unknown" message flag */
+    if((did = H5Dcreate2(loc_id, "Dataset4", H5T_NATIVE_INT, sid, H5P_DEFAULT, dcpl, H5P_DEFAULT)) < 0) goto error;
     if(H5Dclose(did) < 0) goto error;
 
     /* Close dataset creation property list */
@@ -83,9 +92,6 @@ int main(void)
     /* Close dataspace */
     if(H5Sclose(sid) < 0) goto error;
 
-    /* Close file */
-    if(H5Fclose(fid) < 0) goto error;
-
     return 0;
 
 error:
@@ -93,6 +99,43 @@ error:
         H5Dclose(did);
         H5Sclose(sid);
         H5Pclose(dcpl);
+    } H5E_END_TRY;
+
+    return -1;
+} /* generate_datasets() */
+#endif
+
+int main(void)
+{
+#ifdef H5O_ENABLE_BOGUS
+    hid_t fid = -1;             /* File ID */
+    hid_t gid = -1;             /* Group ID */
+
+    /* Create file for test datasets */
+    if((fid = H5Fcreate(FILENAME, H5F_ACC_TRUNC, H5P_DEFAULT, H5P_DEFAULT)) < 0) goto error;
+
+    /* Create datasets in "/" group with bogus message H5O_BOGUS_VALID_ID */
+    if(generate_datasets(fid, H5O_BOGUS_VALID_ID) < 0)
+        goto error;
+
+    if((gid = H5Gcreate2(fid, "group", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0)
+        goto error;
+
+    /* Create datasets in "/group" with bogus message H5O_BOGUS_INVALID_ID */
+    if(generate_datasets(gid, H5O_BOGUS_INVALID_ID) < 0)
+        goto error;
+
+    /* Close the group */
+    if(H5Gclose(gid) < 0) goto error;
+
+    /* Close file */
+    if(H5Fclose(fid) < 0) goto error;
+
+    return 0;
+
+error:
+    H5E_BEGIN_TRY {
+        H5Gclose(gid);
         H5Fclose(fid);
     } H5E_END_TRY;
 #else /* H5O_ENABLE_BOGUS */
@@ -100,4 +143,3 @@ error:
 #endif /* H5O_ENABLE_BOGUS */
     return 1;
 }
-
diff --git a/test/ohdr.c b/test/ohdr.c
index 1b324a9..6e6faa4 100644
--- a/test/ohdr.c
+++ b/test/ohdr.c
@@ -288,6 +288,280 @@ error:
     return -1;
 } /* test_ohdr_cache() */
 
+/*
+ *  To test objects with unknown messages in a file with:
+ *  	a) H5O_BOGUS_VALID_ID:
+ *	   --the bogus_id is within the range of H5O_msg_class_g[]
+ *  	b) H5O_BOGUS_INVALID_ID:
+ *  	   --the bogus_id is outside the range of H5O_msg_class_g[]
+ *
+ *   The test file is FILE_BOGUS: "tbogus.h5" generated with gen_bogus.c
+ *   --objects that have unknown header messages with H5O_BOGUS_VALID_ID in "/"
+ *   --objects that have unknown header messages with H5O_BOGUS_INVALID_ID in "/group"
+ *
+ *   The test also uses the test file FILENAME[0] (ohdr.h5): the parameter "filename"
+ */
+static herr_t
+test_unknown(unsigned bogus_id, char *filename, hid_t fapl)
+{
+    hid_t fid = -1;	/* file ID */
+    hid_t gid = -1;	/* group ID */
+    hid_t did = -1;	/* Dataset ID */
+    hid_t sid = -1;     /* Dataspace ID */
+    hid_t aid = -1;     /* Attribute ID */
+    hid_t loc = -1;	/* location: file or group ID */
+    hid_t fid_bogus = -1;	/* bogus file ID */
+    hid_t gid_bogus = -1;	/* bogus group ID */
+    hid_t loc_bogus = -1;	/* location: bogus file or group ID */
+    char testfile[256];
+
+    /* create a different name for a local copy of the data file to be
+       opened with rd/wr file permissions in case build and test are
+       done in the source directory. */
+    HDstrncpy(testfile, FILE_BOGUS, strlen(FILE_BOGUS));
+    testfile[strlen(FILE_BOGUS)]='\0';
+    HDstrncat(testfile, ".copy", 5);
+
+    /* Make a copy of the data file from svn. */
+    if(h5_make_local_copy(FILE_BOGUS, testfile) < 0)
+      FAIL_STACK_ERROR
+
+    TESTING("object with unknown header message and no flags set");
+
+    /* Open filename */
+    if((fid = H5Fopen(filename, H5F_ACC_RDWR, fapl)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Open FILE_BOGUS */
+    if((fid_bogus = H5Fopen(testfile, H5F_ACC_RDONLY, H5P_DEFAULT)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Set up location ID depending on bogus_id */
+    if(bogus_id == H5O_BOGUS_INVALID_ID) {
+        /* Open "group" in FILE_BOGUS */
+        if((gid_bogus = H5Gopen2(fid_bogus, "group", H5P_DEFAULT)) < 0) 
+            FAIL_STACK_ERROR
+        loc_bogus = gid_bogus;
+
+        /* Create "group" in filename */
+        if((gid = H5Gcreate2(fid, "group", H5P_DEFAULT, H5P_DEFAULT, H5P_DEFAULT)) < 0)
+            FAIL_STACK_ERROR
+        loc = gid;
+
+    } else { /* H5O_BOGUS_VALID_ID */
+        loc_bogus = fid_bogus;
+        loc = fid;
+    } /* end else */
+
+   /* Open the dataset with the unknown header message, but no extra flags */
+    if((did = H5Dopen2(loc_bogus, "Dataset1", H5P_DEFAULT)) < 0)
+        FAIL_STACK_ERROR
+    if(H5Dclose(did) < 0)
+        FAIL_STACK_ERROR
+
+    PASSED();
+
+    TESTING("object in r/o file with unknown header message & 'fail if unknown and open for write' flag set");
+
+    /* Open the dataset with the unknown header message, and "fail if unknown and open for write" flag */
+    if((did = H5Dopen2(loc_bogus, "Dataset2", H5P_DEFAULT)) < 0)
+        FAIL_STACK_ERROR
+    if(H5Dclose(did) < 0)
+        FAIL_STACK_ERROR
+
+    PASSED();
+
+    /* TESTING("object in r/o file with unknown header message & 'fail if unknown always' flag set"); */
+    /* There is no H5O_MSG_FLAG_FAIL_IF_UNKNOWN_ALWAYS */
+
+    TESTING("object with unknown header message & 'mark if unknown' flag set");
+
+    /* Copy object with "mark if unknown" flag on message into file (FILENAME[0]) that can be modified */
+    if(H5Ocopy(loc_bogus, "Dataset4", loc, "Dataset4", H5P_DEFAULT, H5P_DEFAULT) < 0)
+        FAIL_STACK_ERROR
+
+    /* Closing: filename */
+    if(bogus_id == H5O_BOGUS_INVALID_ID)
+        if(H5Gclose(gid) < 0)
+            FAIL_STACK_ERROR
+    if(H5Fclose(fid) < 0)
+       FAIL_STACK_ERROR
+
+    /* Re-open filename, with read-only permissions */
+    if((fid = H5Fopen(filename, H5F_ACC_RDONLY, fapl)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Set up location ID depending on bogus_id */
+    if(bogus_id == H5O_BOGUS_INVALID_ID) {
+        /* Open "group" in filename */
+        if((gid = H5Gopen2(fid, "group", H5P_DEFAULT)) < 0) 
+            FAIL_STACK_ERROR
+        loc = gid;
+    } else
+        loc = fid;
+
+    /* Open the dataset with the "mark if unknown" message */
+    if((did = H5Dopen2(loc, "Dataset4", H5P_DEFAULT)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Check that the "unknown" message was _NOT_ marked */
+    if(H5O_check_msg_marked_test(did, FALSE) < 0)
+        FAIL_STACK_ERROR
+
+    /* Close the dataset */
+    if(H5Dclose(did) < 0)
+        FAIL_STACK_ERROR
+
+    /* Close "group" in filename depending on bogus_id */
+    if(bogus_id == H5O_BOGUS_INVALID_ID)
+        if(H5Gclose(gid) < 0)
+            FAIL_STACK_ERROR
+
+    /* Close filename (to flush change to object header) */
+    if(H5Fclose(fid) < 0)
+        FAIL_STACK_ERROR
+
+    /* Re-open filename */
+    if((fid = H5Fopen(filename, H5F_ACC_RDWR, fapl)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Set up location ID depending on bogus_id */
+    if(bogus_id == H5O_BOGUS_INVALID_ID) {
+        /* Open "group" in filename */
+        if((gid = H5Gopen2(fid, "group", H5P_DEFAULT)) < 0) 
+            FAIL_STACK_ERROR
+        loc = gid;
+    } else
+        loc = fid;
+
+    /* Open the dataset with the "mark if unknown" message */
+    if((did = H5Dopen2(loc, "Dataset4", H5P_DEFAULT)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Create data space */
+    if((sid = H5Screate(H5S_SCALAR)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Create an attribute, to get the object header into write access */
+    if((aid = H5Acreate2(did, "Attr", H5T_NATIVE_INT, sid, H5P_DEFAULT, H5P_DEFAULT)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Close dataspace */
+    if(H5Sclose(sid) < 0)
+        FAIL_STACK_ERROR
+
+    /* Close attribute */
+    if(H5Aclose(aid) < 0)
+        FAIL_STACK_ERROR
+
+    /* Close the dataset */
+    if(H5Dclose(did) < 0)
+        FAIL_STACK_ERROR
+
+    /* Close "group" in filename depending on bogus_id */
+    if(bogus_id == H5O_BOGUS_INVALID_ID)
+        if(H5Gclose(gid) < 0)
+            FAIL_STACK_ERROR
+
+    /* Close filename (to flush change to object header) */
+    if(H5Fclose(fid) < 0)
+        FAIL_STACK_ERROR
+
+    /* Re-open filename */
+    if((fid = H5Fopen(filename, H5F_ACC_RDONLY, fapl)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Set up location ID depending on bogus_id */
+    if(bogus_id == H5O_BOGUS_INVALID_ID) {
+        /* Open "group" in filename */
+        if((gid = H5Gopen2(fid, "group", H5P_DEFAULT)) < 0) 
+            FAIL_STACK_ERROR
+        loc = gid;
+    } else
+        loc = fid;
+
+    /* Re-open the dataset with the "mark if unknown" message */
+    if((did = H5Dopen2(loc, "Dataset4", H5P_DEFAULT)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Check that the "unknown" message was marked */
+    if(H5O_check_msg_marked_test(did, TRUE) < 0)
+        FAIL_STACK_ERROR
+
+    /* Close the dataset */
+    if(H5Dclose(did) < 0)
+        FAIL_STACK_ERROR
+
+    /* Closing: filename */ 
+    if(bogus_id == H5O_BOGUS_INVALID_ID)
+        if(H5Gclose(gid) < 0)
+            FAIL_STACK_ERROR
+    if(H5Fclose(fid) < 0)
+        FAIL_STACK_ERROR
+
+    PASSED();
+
+    /* Closing: FILE_BOGUS */
+    if(bogus_id == H5O_BOGUS_INVALID_ID)
+        if(H5Gclose(gid_bogus) < 0)
+            FAIL_STACK_ERROR
+    if(H5Fclose(fid_bogus) < 0)
+        FAIL_STACK_ERROR
+
+    TESTING("object in r/w file with unknown header message & 'fail if unknown and open for write' flag set");
+
+    /* Open FILE_BOGUS with RW intent this time */
+    if((fid_bogus = H5Fopen(testfile, H5F_ACC_RDWR, H5P_DEFAULT)) < 0)
+        FAIL_STACK_ERROR
+
+    /* Set up location ID */
+    if(bogus_id == H5O_BOGUS_INVALID_ID) {
+        /* Open "group" in FILE_BOGUS */
+        if((gid_bogus = H5Gopen2(fid_bogus, "group", H5P_DEFAULT)) < 0) 
+            FAIL_STACK_ERROR
+        loc_bogus = gid_bogus;
+    } else
+        loc_bogus = fid_bogus;
+
+    /* Attempt to open the dataset with the unknown header message, and "fail if unknown and open for write" flag */
+    H5E_BEGIN_TRY {
+        did = H5Dopen2(loc_bogus, "Dataset2", H5P_DEFAULT);
+    } H5E_END_TRY;
+    if(did >= 0) {
+        H5Dclose(did);
+        TEST_ERROR
+    } /* end if */
+
+    PASSED();
+
+    /* TESTING("object in r/w file with unknown header message & 'fail if unknown always' flag set"); */
+    /* There is no H5O_MSG_FLAG_FAIL_IF_UNKNOWN_ALWAYS */
+
+    /* Closing: FILE_BOGUS */
+    if(bogus_id == H5O_BOGUS_INVALID_ID)
+        if(H5Gclose(gid_bogus) < 0)
+	        FAIL_STACK_ERROR
+    if(H5Fclose(fid_bogus) < 0)
+        FAIL_STACK_ERROR
+
+    PASSED();
+
+    return SUCCEED;
+
+error:
+    H5E_BEGIN_TRY {
+        H5Fclose(fid);
+        H5Gclose(gid);
+        H5Fclose(fid_bogus);
+        H5Gclose(gid_bogus);
+        H5Dclose(did);
+        H5Sclose(sid);
+        H5Aclose(aid);
+    } H5E_END_TRY;
+
+    return FAIL;
+} /* test_unknown() */
+
 
 /*-------------------------------------------------------------------------
  * Function:	main
@@ -334,8 +608,8 @@ main(void)
         if(H5Pset_libver_bounds(fapl, (b ? H5F_LIBVER_LATEST : H5F_LIBVER_EARLIEST), H5F_LIBVER_LATEST) < 0)
             FAIL_STACK_ERROR
 
-	/* test on object continuation block */
-	if(test_cont(filename, fapl) < 0)
+        /* test on object continuation block */
+        if(test_cont(filename, fapl) < 0)
             FAIL_STACK_ERROR
 
         /* Create the file to operate on */
@@ -650,164 +924,22 @@ main(void)
 
         PASSED();
 
-
-        /* Test reading datasets with undefined object header messages */
-        HDputs("Accessing objects with unknown header messages:");
-        {
-            hid_t file2;                    /* File ID for 'bogus' object file */
-            hid_t sid;                      /* Dataspace ID */
-            hid_t aid;                      /* Attribute ID */
-            char testpath[512] = "";
-            char testfile[512] = "";
-            char *srcdir = HDgetenv("srcdir");
-
-            /* Build path to all test files */
-            if(srcdir && ((HDstrlen(srcdir) + 2) < sizeof(testpath))) {
-                HDstrcpy(testpath, srcdir);
-                HDstrcat(testpath, "/");
-            } /* end if */
-
-            /* Build path to test file */
-            if(srcdir && ((HDstrlen(testpath) + HDstrlen(FILE_BOGUS) + 1) < sizeof(testfile)))
-                HDstrcpy(testfile, testpath);
-            HDstrcat(testfile, FILE_BOGUS);
-
-            TESTING("object with unknown header message and no flags set");
-
-            /* Open the file with objects that have unknown header messages (generated with gen_bogus.c) */
-            if((file2 = H5Fopen(testfile, H5F_ACC_RDONLY, H5P_DEFAULT)) < 0)
-                TEST_ERROR
-
-            /* Open the dataset with the unknown header message, but no extra flags */
-            if((dset = H5Dopen2(file2, "/Dataset1", H5P_DEFAULT)) < 0)
-                TEST_ERROR
-            if(H5Dclose(dset) < 0)
-                TEST_ERROR
-
-            PASSED();
-
-            TESTING("object with unknown header message & 'fail if unknown and open for write' flag set");
-
-            /* Open the dataset with the unknown header message, and "fail if unknown and open for write" flag */
-            if((dset = H5Dopen2(file2, "/Dataset2", H5P_DEFAULT)) < 0)
-                TEST_ERROR
-            if(H5Dclose(dset) < 0)
-                TEST_ERROR
-
-            PASSED();
-
-            TESTING("object with unknown header message & 'mark if unknown' flag set");
-
-            /* Copy object with "mark if unknown" flag on message into file that can be modified */
-            if(H5Ocopy(file2, "/Dataset3", file, "/Dataset3", H5P_DEFAULT, H5P_DEFAULT) < 0)
-                TEST_ERROR
-
-            /* Close the file we created (to flush changes to file) */
-            if(H5Fclose(file) < 0)
-                TEST_ERROR
-
-            /* Re-open the file created, with read-only permissions */
-            if((file = H5Fopen(filename, H5F_ACC_RDONLY, fapl)) < 0)
-                TEST_ERROR
-
-            /* Open the dataset with the "mark if unknown" message */
-            if((dset = H5Dopen2(file, "/Dataset3", H5P_DEFAULT)) < 0)
-                TEST_ERROR
-
-            /* Check that the "unknown" message was _NOT_ marked */
-            if(H5O_check_msg_marked_test(dset, FALSE) < 0)
-                FAIL_STACK_ERROR
-
-            /* Close the dataset */
-            if(H5Dclose(dset) < 0)
-                TEST_ERROR
-
-            /* Close the file we created (to flush change to object header) */
-            if(H5Fclose(file) < 0)
-                TEST_ERROR
-
-            /* Re-open the file created */
-            if((file = H5Fopen(filename, H5F_ACC_RDWR, fapl)) < 0)
-                TEST_ERROR
-
-            /* Open the dataset with the "mark if unknown" message */
-            if((dset = H5Dopen2(file, "/Dataset3", H5P_DEFAULT)) < 0)
-                TEST_ERROR
-
-            /* Create data space */
-            if((sid = H5Screate(H5S_SCALAR)) < 0)
-                FAIL_STACK_ERROR
-
-            /* Create an attribute, to get the object header into write access */
-            if((aid = H5Acreate2(dset, "Attr", H5T_NATIVE_INT, sid, H5P_DEFAULT, H5P_DEFAULT)) < 0)
-                FAIL_STACK_ERROR
-
-            /* Close dataspace */
-            if(H5Sclose(sid) < 0)
-                FAIL_STACK_ERROR
-
-            /* Close attribute */
-            if(H5Aclose(aid) < 0)
-                FAIL_STACK_ERROR
-
-            /* Close the dataset */
-            if(H5Dclose(dset) < 0)
-                TEST_ERROR
-
-            /* Close the file we created (to flush change to object header) */
-            if(H5Fclose(file) < 0)
-                TEST_ERROR
-
-            /* Re-open the file created */
-            if((file = H5Fopen(filename, H5F_ACC_RDONLY, fapl)) < 0)
-                TEST_ERROR
-
-            /* Re-open the dataset with the "mark if unknown" message */
-            if((dset = H5Dopen2(file, "/Dataset3", H5P_DEFAULT)) < 0)
-                TEST_ERROR
-
-            /* Check that the "unknown" message was marked */
-            if(H5O_check_msg_marked_test(dset, TRUE) < 0)
-                FAIL_STACK_ERROR
-
-            /* Close the dataset */
-            if(H5Dclose(dset) < 0)
-                TEST_ERROR
-
-            /* Close the file with the bogus objects */
-            if(H5Fclose(file2) < 0)
-                TEST_ERROR
-
-            PASSED();
-
-            /* Open the file with objects that have unknown header messages (generated with gen_bogus.c) with RW intent this time */
-            if((file2 = H5Fopen(testfile, H5F_ACC_RDWR, H5P_DEFAULT)) < 0)
-                TEST_ERROR
-
-            TESTING("object with unknown header message & 'fail if unknown and open for write' flag set");
-
-            /* Attempt to open the dataset with the unknown header message, and "fail if unknown and open for write" flag */
-            H5E_BEGIN_TRY {
-                dset = H5Dopen2(file2, "/Dataset2", H5P_DEFAULT);
-            } H5E_END_TRY;
-            if(dset >= 0) {
-                H5Dclose(dset);
-                TEST_ERROR
-            } /* end if */
-
-            /* Close the file with the bogus objects */
-            if(H5Fclose(file2) < 0)
-                TEST_ERROR
-
-            PASSED();
-        }
-
-        /* Close the file we created */
+         /* Close the file we created */
         if(H5Fclose(file) < 0)
             TEST_ERROR
 
-	/* Test object header creation metadata cache issues */
-	if(test_ohdr_cache(filename, fapl) < 0)
+        /* Test reading datasets with undefined object header messages
+         * and the various "fail/mark if unknown" object header message flags
+         */
+        HDputs("Accessing objects with unknown header messages: H5O_BOGUS_VALID_ID");
+        if(test_unknown(H5O_BOGUS_VALID_ID, filename, fapl) < 0)
+            TEST_ERROR
+        HDputs("Accessing objects with unknown header messages: H5O_BOGUS_INVALID_ID");
+        if(test_unknown(H5O_BOGUS_INVALID_ID, filename, fapl) < 0)
+            TEST_ERROR
+
+        /* Test object header creation metadata cache issues */
+        if(test_ohdr_cache(filename, fapl) < 0)
             TEST_ERROR
     } /* end for */
 
diff --git a/test/tbogus.h5 b/test/tbogus.h5
index 5b1d85e..87b183b 100644
--- a/test/tbogus.h5
+++ b/test/tbogus.h5