[svn-r24188] Purpose: Fixed bug introduced in r24163

Description:
    - The failure in daily test was caused by missing initialization of member
    "id" in a few constructors.  This is now fixed.
    - Added two overloaded H5Location::setComment
    - Improved some error reporting in H5Location
    - Improved error reporting in tests
Platforms tested:
    Linux/32 2.6 (jam)
    SunOS 5.11 (emu)
    Linux/64 2.6 (koala)/PGI compilers

17 files changed, 399 insertions, 453 deletions

diff --git a/c++/src/H5Attribute.cpp b/c++/src/H5Attribute.cpp
index d684b8f..a98a970 100644
--- a/c++/src/H5Attribute.cpp
+++ b/c++/src/H5Attribute.cpp
@@ -44,6 +44,7 @@ namespace H5 {
 #endif  // H5_NO_STD
 #endif
 
+class H5_DLLCPP H5Object;  // forward declaration for UserData4Aiterate
 //--------------------------------------------------------------------------
 // Function:	Attribute default constructor
 ///\brief	Default constructor: Creates a stub attribute
diff --git a/c++/src/H5CommonFG.cpp b/c++/src/H5CommonFG.cpp
index d6fe5dc..3bf4b4f 100644
--- a/c++/src/H5CommonFG.cpp
+++ b/c++/src/H5CommonFG.cpp
@@ -460,137 +460,6 @@ H5std_string CommonFG::getLinkval( const H5std_string& name, size_t size ) const
 }
 
 //--------------------------------------------------------------------------
-// Function:	CommonFG::setComment
-///\brief	Sets or resets the comment for an object specified by its name.
-///\param	name  - IN: Name of the object
-///\param	comment - IN: New comment
-///\exception	H5::FileIException or H5::GroupIException
-///\par	Description
-///		If \a comment is an empty string or a null pointer, the comment
-///		message is removed from the object.
-///		Comments should be relatively short, null-terminated, ASCII
-///		strings.  They can be attached to any object that has an
-///		object header, e.g., data sets, groups, named data types,
-///		and data spaces, but not symbolic links.
-// Programmer	Binh-Minh Ribler - 2000
-// Modification
-//	2007: QAK modified to use H5O APIs; however the first parameter is
-//		no longer just file or group, this function should be moved
-//		to another class to accommodate attribute, dataset, and named
-//		datatype. - BMR
-//--------------------------------------------------------------------------
-void CommonFG::setComment( const char* name, const char* comment ) const
-{
-   herr_t ret_value = H5Oset_comment_by_name( getLocId(), name, comment, H5P_DEFAULT );
-   if( ret_value < 0 )
-      throwException("setComment", "H5Oset_comment_by_name failed");
-}
-
-//--------------------------------------------------------------------------
-// Function:	CommonFG::setComment
-///\brief	This is an overloaded member function, provided for convenience.
-///		It differs from the above function in that it takes an
-///		\c H5std_string for \a name and \a comment.
-// Programmer	Binh-Minh Ribler - 2000
-//--------------------------------------------------------------------------
-void CommonFG::setComment( const H5std_string& name, const H5std_string& comment ) const
-{
-   setComment( name.c_str(), comment.c_str() );
-}
-
-//--------------------------------------------------------------------------
-// Function:	CommonFG::removeComment
-///\brief	Removes the comment from an object specified by its name.
-///\param	name  - IN: Name of the object
-///\exception	H5::FileIException or H5::GroupIException
-// Programmer	Binh-Minh Ribler - May 2005
-//	2007: QAK modified to use H5O APIs; however the first parameter is
-//		no longer just file or group, this function should be moved
-//		to another class to accommodate attribute, dataset, and named
-//		datatype. - BMR
-//--------------------------------------------------------------------------
-void CommonFG::removeComment(const char* name) const
-{
-   herr_t ret_value = H5Oset_comment_by_name(getLocId(), name, NULL, H5P_DEFAULT);
-   if( ret_value < 0 )
-      throwException("removeComment", "H5Oset_comment_by_name failed");
-}
-
-//--------------------------------------------------------------------------
-// Function:	CommonFG::removeComment
-///\brief	This is an overloaded member function, provided for convenience.
-///		It differs from the above function in that it takes an
-///		\c H5std_string for \a name.
-// Programmer	Binh-Minh Ribler - May 2005
-//--------------------------------------------------------------------------
-void CommonFG::removeComment(const H5std_string& name) const
-{
-   removeComment (name.c_str());
-}
-
-//--------------------------------------------------------------------------
-// Function:	CommonFG::getComment
-///\brief	Retrieves comment for the specified object and its comment's
-///		length.
-///\param	name  - IN: Name of the object
-///\param	bufsize - IN: Length of the comment to retrieve
-///\return	Comment string
-///\exception	H5::FileIException or H5::GroupIException
-// Programmer	Binh-Minh Ribler - 2000
-//	2007: QAK modified to use H5O APIs; however the first parameter is
-//		no longer just file or group, this function should be moved
-//		to another class to accommodate attribute, dataset, and named
-//		datatype. - BMR
-//--------------------------------------------------------------------------
-H5std_string CommonFG::getComment( const char* name, size_t bufsize ) const
-{
-   // bufsize is default to 256
-   // temporary variable
-   hid_t loc_id = getLocId();   // temporary variable
-
-   // temporary C-string for the object's comment; bufsize already including
-   // null character
-   char* comment_C = new char[bufsize];
-   ssize_t ret_value = H5Oget_comment_by_name(loc_id, name, comment_C, bufsize, H5P_DEFAULT);
-
-   // if the actual length of the comment is longer than bufsize and bufsize
-   // was the default value, i.e., not given by the user, then call
-   // H5Oget_comment_by_name again with the correct value.
-   // If the call to H5Oget_comment_by_name returned an error, skip this block
-   // and throw an exception below.
-   if (ret_value >= 0 && (size_t)ret_value > bufsize && bufsize == 256)
-   {
-	size_t new_size = ret_value;
-	delete []comment_C;
-	comment_C = new char[new_size];	// new_size including null terminator
-	ret_value = H5Oget_comment_by_name(loc_id, name, comment_C, new_size, H5P_DEFAULT);
-   }
-
-   // if H5Oget_comment_by_name returns SUCCEED, return the string comment,
-   // otherwise, throw an exception
-   if( ret_value < 0 ) {
-       delete []comment_C;
-       throwException("getComment", "H5Oget_comment_by_name failed");
-   }
-
-   H5std_string comment = H5std_string(comment_C);
-   delete []comment_C;
-   return (comment);
-}
-
-//--------------------------------------------------------------------------
-// Function:	CommonFG::getComment
-///\brief	This is an overloaded member function, provided for convenience.
-///		It differs from the above function in that it takes an
-///		\c H5std_string for \a name.
-// Programmer	Binh-Minh Ribler - 2000
-//--------------------------------------------------------------------------
-H5std_string CommonFG::getComment( const H5std_string& name, size_t bufsize ) const
-{
-   return( getComment( name.c_str(), bufsize ));
-}
-
-//--------------------------------------------------------------------------
 // Function:	CommonFG::mount
 ///\brief	Mounts the file \a child onto this group.
 ///\param	name  - IN: Name of the group
diff --git a/c++/src/H5CommonFG.h b/c++/src/H5CommonFG.h
index 22e193a..b02b05b 100644
--- a/c++/src/H5CommonFG.h
+++ b/c++/src/H5CommonFG.h
@@ -49,18 +49,6 @@ class H5_DLLCPP CommonFG {
 	DataSet openDataSet(const char* name) const;
 	DataSet openDataSet(const H5std_string& name) const;
 
-	// Retrieves comment for the HDF5 object specified by its name.
-	H5std_string getComment(const char* name, size_t bufsize=256) const;
-	H5std_string getComment(const H5std_string& name, size_t bufsize=256) const;
-
-	// Removes the comment for the HDF5 object specified by its name.
-	void removeComment(const char* name) const;
-	void removeComment(const H5std_string& name) const;
-
-	// Sets the comment for an HDF5 object specified by its name.
-	void setComment(const char* name, const char* comment) const;
-	void setComment(const H5std_string& name, const H5std_string& comment) const;
-
 	// Returns the value of a symbolic link.
 	H5std_string getLinkval(const char* link_name, size_t size=0) const;
 	H5std_string getLinkval(const H5std_string& link_name, size_t size=0) const;
diff --git a/c++/src/H5DataSet.cpp b/c++/src/H5DataSet.cpp
index 3e3893c..0722ef9 100644
--- a/c++/src/H5DataSet.cpp
+++ b/c++/src/H5DataSet.cpp
@@ -79,57 +79,29 @@ DataSet::DataSet(const DataSet& original) : AbstractDs(original), H5Object(origi
 
 //--------------------------------------------------------------------------
 // Function:	DataSet overload constructor - dereference
-///\brief	Given a reference, ref, to an hdf5 dataset, creates a
+///\brief	Given a reference, ref, to an hdf5 location, creates a
 ///		DataSet object
-///\param	obj - IN: Dataset reference object is in or location of
+///\param	loc - IN: Dataset reference object is in or location of
 ///			  object that the dataset is located within.
 ///\param	ref - IN: Reference pointer
 ///\param	ref_type - IN: Reference type - default to H5R_OBJECT
 ///\exception	H5::DataSetIException
 ///\par Description
-///		\c obj can be DataSet, Group, H5File, or named DataType, that
+///		\c loc can be DataSet, Group, H5File, or named DataType, that
 ///		is a datatype that has been named by DataType::commit.
 // Programmer	Binh-Minh Ribler - Oct, 2006
 // Modification
 //	Jul, 2008
 //		Added for application convenience.
 //--------------------------------------------------------------------------
-DataSet::DataSet(H5Object& obj, const void* ref, H5R_type_t ref_type) : AbstractDs(), H5Object()
+DataSet::DataSet(const H5Location& loc, const void* ref, H5R_type_t ref_type, const PropList& plist) : AbstractDs(), H5Object(), id(0)
 {
-    try {
-	id = p_dereference(obj.getId(), ref, ref_type);
-    } catch (ReferenceException deref_error) {
-	throw ReferenceException("DataSet constructor - located by object",
-		deref_error.getDetailMsg());
-    }
+    id = H5Location::p_dereference(loc.getId(), ref, ref_type, plist, "constructor - by dereferenced");
 }
 
 //--------------------------------------------------------------------------
 // Function:	DataSet overload constructor - dereference
-///\brief	Given a reference, ref, to an hdf5 dataset, creates a
-///		DataSet object
-///\param	h5file - IN: Location referenced object is in
-///\param	ref - IN: Reference pointer
-///\param	ref_type - IN: Reference type - default to H5R_OBJECT
-///\exception	H5::DataSetIException
-// Programmer	Binh-Minh Ribler - Oct, 2006
-// Modification
-//	Jul, 2008
-//		Added for application convenience.
-//--------------------------------------------------------------------------
-DataSet::DataSet(H5File& h5file, const void* ref, H5R_type_t ref_type) : AbstractDs(), H5Object()
-{
-    try {
-	id = p_dereference(h5file.getId(), ref, ref_type);
-    } catch (ReferenceException deref_error) {
-	throw ReferenceException("DataSet constructor - located by HDF5 file",
-		deref_error.getDetailMsg());
-    }
-}
-
-//--------------------------------------------------------------------------
-// Function:	DataSet overload constructor - dereference
-///\brief	Given a reference, ref, to an hdf5 dataset, creates a
+///\brief	Given a reference, ref, to an hdf5 attribute, creates a
 ///		DataSet object
 ///\param	attr - IN: Specifying location where the referenced object is in
 ///\param	ref - IN: Reference pointer
@@ -140,14 +112,9 @@ DataSet::DataSet(H5File& h5file, const void* ref, H5R_type_t ref_type) : Abstrac
 //	Jul, 2008
 //		Added for application convenience.
 //--------------------------------------------------------------------------
-DataSet::DataSet(Attribute& attr, const void* ref, H5R_type_t ref_type) : AbstractDs(), H5Object()
+DataSet::DataSet(const Attribute& attr, const void* ref, H5R_type_t ref_type, const PropList& plist) : AbstractDs(), H5Object(), id(0)
 {
-    try {
-	id = p_dereference(attr.getId(), ref, ref_type);
-    } catch (ReferenceException deref_error) {
-	throw ReferenceException("DataSet constructor - located by attribute",
-		deref_error.getDetailMsg());
-    }
+    id = H5Location::p_dereference(attr.getId(), ref, ref_type, plist, "constructor - by dereference");
 }
 
 //--------------------------------------------------------------------------
@@ -751,9 +718,6 @@ void DataSet::p_setId(const hid_t new_id)
     }
    // reset object's id to the given id
    id = new_id;
-
-   // increment the reference counter of the new id
-   //incRefCount();
 }
 #endif // DOXYGEN_SHOULD_SKIP_THIS
 
diff --git a/c++/src/H5DataSet.h b/c++/src/H5DataSet.h
index bc80046..e2fe702 100644
--- a/c++/src/H5DataSet.h
+++ b/c++/src/H5DataSet.h
@@ -76,16 +76,12 @@ class H5_DLLCPP DataSet : public H5Object, public AbstractDs {
 	// Iterates the selected elements in the specified dataspace - not implemented in C++ style yet
         int iterateElems( void* buf, const DataType& type, const DataSpace& space, H5D_operator_t op, void* op_data = NULL );
 
-	// Retrieves a dataspace with the region pointed to selected.
-	DataSpace getRegion(void *ref, H5R_type_t ref_type = H5R_DATASET_REGION) const;
-
 	///\brief Returns this class name.
 	virtual H5std_string fromClass () const { return("DataSet"); }
 
 	// Creates a dataset by way of dereference.
-	DataSet(H5Object& obj, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
-	DataSet(H5File& h5file, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
-	DataSet(Attribute& attr, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	DataSet(const H5Location& loc, const void* ref, H5R_type_t ref_type = H5R_OBJECT, const PropList& plist = PropList::DEFAULT);
+	DataSet(const Attribute& attr, const void* ref, H5R_type_t ref_type = H5R_OBJECT, const PropList& plist = PropList::DEFAULT);
 
 	// Default constructor.
 	DataSet();
diff --git a/c++/src/H5DataSpace.cpp b/c++/src/H5DataSpace.cpp
index 2e2bb35..059c812 100644
--- a/c++/src/H5DataSpace.cpp
+++ b/c++/src/H5DataSpace.cpp
@@ -446,7 +446,7 @@ void DataSpace::getSelectBounds ( hsize_t* start, hsize_t* end ) const
 }
 
 //--------------------------------------------------------------------------
-// Function:	DataSpace::H5Sselect_elements
+// Function:	DataSpace::selectElements
 ///\brief	Selects array elements to be included in the selection for
 ///		this dataspace.
 ///\param	op  - IN: Operator specifying how the new selection is to be
diff --git a/c++/src/H5DataType.cpp b/c++/src/H5DataType.cpp
index 8a62471..be05623 100644
--- a/c++/src/H5DataType.cpp
+++ b/c++/src/H5DataType.cpp
@@ -49,6 +49,13 @@ namespace H5 {
 #endif
 
 //--------------------------------------------------------------------------
+// Function:	DataType default constructor
+///\brief	Default constructor: Creates a stub datatype
+// Programmer	Binh-Minh Ribler - 2000
+//--------------------------------------------------------------------------
+DataType::DataType() : H5Object(), id(0) {}
+
+//--------------------------------------------------------------------------
 // Function:	DataType overloaded constructor
 ///\brief	Creates a datatype using an existing datatype's id
 ///\param	existing_id - IN: Id of the existing datatype
@@ -88,32 +95,6 @@ DataType::DataType( const H5T_class_t type_class, size_t size ) : H5Object()
 // Function:	DataType overload constructor - dereference
 ///\brief	Given a reference, ref, to an hdf5 group, creates a
 ///		DataType object
-///\param       obj - IN: Specifying location referenced object is in
-///\param	ref - IN: Reference pointer
-///\param	ref_type - IN: Reference type - default to H5R_OBJECT
-///\exception	H5::ReferenceException
-///\par Description
-///		\c obj can be DataSet, Group, or named DataType, that
-///		is a datatype that has been named by DataType::commit.
-// Programmer	Binh-Minh Ribler - Oct, 2006
-// Modification
-//	Jul, 2008
-//		Added for application convenience.
-//--------------------------------------------------------------------------
-DataType::DataType(H5Object& obj, const void* ref, H5R_type_t ref_type) : H5Object()
-{
-    try {
-	id = p_dereference(obj.getId(), ref, ref_type);
-    } catch (ReferenceException deref_error) {
-	throw ReferenceException("DataType constructor - located by an H5Object",
-		deref_error.getDetailMsg());
-    }
-}
-
-//--------------------------------------------------------------------------
-// Function:	DataType overload constructor - dereference
-///\brief	Given a reference, ref, to an hdf5 group, creates a
-///		DataType object
 ///\param       h5file - IN: Location referenced object is in
 ///\param	ref - IN: Reference pointer
 ///\param	ref_type - IN: Reference type - default to H5R_OBJECT
@@ -123,14 +104,11 @@ DataType::DataType(H5Object& obj, const void* ref, H5R_type_t ref_type) : H5Obje
 //	Jul, 2008
 //		Added for application convenience.
 //--------------------------------------------------------------------------
-DataType::DataType(H5File& h5file, const void* ref, H5R_type_t ref_type) : H5Object()
+DataType::DataType(const H5Location& loc, const void* ref, H5R_type_t ref_type, const PropList& plist) : H5Object(), id(0)
 {
-    try {
-	id = p_dereference(h5file.getId(), ref, ref_type);
-    } catch (ReferenceException deref_error) {
-	throw ReferenceException("DataType constructor - located by an H5File",
-		deref_error.getDetailMsg());
-    }
+ /*     H5Location::dereference(loc, ref, ref_type, plist);
+ */ 
+    id = H5Location::p_dereference(loc.getId(), ref, ref_type, plist, "constructor - by dereference");
 }
 
 //--------------------------------------------------------------------------
@@ -146,24 +124,19 @@ DataType::DataType(H5File& h5file, const void* ref, H5R_type_t ref_type) : H5Obj
 //	Jul, 2008
 //		Added for application convenience.
 //--------------------------------------------------------------------------
-DataType::DataType(Attribute& attr, const void* ref, H5R_type_t ref_type) : H5Object()
+DataType::DataType(const Attribute& attr, const void* ref, H5R_type_t ref_type, const PropList& plist) : H5Object(), id(0)
 {
-    try {
-	id = p_dereference(attr.getId(), ref, ref_type);
+    id = H5Location::p_dereference(attr.getId(), ref, ref_type, plist, "constructor - by dereference");
+     /* try {
+	id = p_dereference(attr.getId(), ref, ref_type, plist);
     } catch (ReferenceException deref_error) {
 	throw ReferenceException("DataType constructor - located by an Attribute",
 		deref_error.getDetailMsg());
     }
+ */ 
 }
 
 //--------------------------------------------------------------------------
-// Function:	DataType default constructor
-///\brief	Default constructor: Creates a stub datatype
-// Programmer	Binh-Minh Ribler - 2000
-//--------------------------------------------------------------------------
-DataType::DataType() : H5Object(), id(0) {}
-
-//--------------------------------------------------------------------------
 // Function:	DataType copy constructor
 ///\brief	Copy constructor: makes a copy of the original DataType object.
 // Programmer	Binh-Minh Ribler - 2000
diff --git a/c++/src/H5DataType.h b/c++/src/H5DataType.h
index 6e56622..e4254b0 100644
--- a/c++/src/H5DataType.h
+++ b/c++/src/H5DataType.h
@@ -30,9 +30,8 @@ class H5_DLLCPP DataType : public H5Object {
 	DataType( const DataType& original );
 
 	// Creates a datatype by way of dereference.
-	DataType(H5Object& obj, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
-	DataType(H5File& h5file, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
-	DataType(Attribute& attr, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	DataType(const H5Location& loc, const void* ref, H5R_type_t ref_type = H5R_OBJECT, const PropList& plist = PropList::DEFAULT);
+	DataType(const Attribute& attr, const void* ref, H5R_type_t ref_type = H5R_OBJECT, const PropList& plist = PropList::DEFAULT);
 
 	// Closes this datatype.
 	virtual void close();
@@ -101,9 +100,6 @@ class H5_DLLCPP DataType : public H5Object {
 	// Checks whether this datatype is a variable-length string.
 	bool isVariableStr() const;
 
-	// Retrieves a dataspace with the region pointed to selected.
-	DataSpace getRegion(void *ref, H5R_type_t ref_type = H5R_DATASET_REGION) const;
-
 	///\brief Returns this class name.
 	virtual H5std_string fromClass () const { return("DataType"); }
 
diff --git a/c++/src/H5File.cpp b/c++/src/H5File.cpp
index 65191ae..77dd7be 100644
--- a/c++/src/H5File.cpp
+++ b/c++/src/H5File.cpp
@@ -82,7 +82,7 @@ H5File::H5File() : H5Location(), id(0) {}
 //		to catch then re-throw it. -BMR 2013/03/21
 // Programmer	Binh-Minh Ribler - 2000
 //--------------------------------------------------------------------------
-H5File::H5File( const char* name, unsigned int flags, const FileCreatPropList& create_plist, const FileAccPropList& access_plist ) : H5Location(0)
+H5File::H5File( const char* name, unsigned int flags, const FileCreatPropList& create_plist, const FileAccPropList& access_plist ) : H5Location(), id(0)
 {
     try {
 	p_get_file(name, flags, create_plist, access_plist);
@@ -107,7 +107,7 @@ H5File::H5File( const char* name, unsigned int flags, const FileCreatPropList& c
 //		to catch then re-throw it. -BMR 2013/03/21
 // Programmer	Binh-Minh Ribler - 2000
 //--------------------------------------------------------------------------
-H5File::H5File( const H5std_string& name, unsigned int flags, const FileCreatPropList& create_plist, const FileAccPropList& access_plist ) : H5Location(0)
+H5File::H5File( const H5std_string& name, unsigned int flags, const FileCreatPropList& create_plist, const FileAccPropList& access_plist ) : H5Location(), id(0)
 {
     try {
 	p_get_file(name.c_str(), flags, create_plist, access_plist);
diff --git a/c++/src/H5File.h b/c++/src/H5File.h
index f906de6..2abffea 100644
--- a/c++/src/H5File.h
+++ b/c++/src/H5File.h
@@ -61,9 +61,6 @@ class H5_DLLCPP H5File : public H5Location, public CommonFG {
 	// and datatypes) in the same file.
 	void getObjIDs(unsigned types, size_t max_objs, hid_t *oid_list) const;
 
-	// Retrieves a dataspace with the region pointed to selected.
-	DataSpace getRegion(void *ref, H5R_type_t ref_type = H5R_DATASET_REGION) const;
-
 	// Returns the pointer to the file handle of the low-level file driver.
 	void getVFDHandle(FileAccPropList& fapl, void **file_handle) const;
 	void getVFDHandle(void **file_handle) const;
diff --git a/c++/src/H5Group.cpp b/c++/src/H5Group.cpp
index eff7e50..6299ea3 100644
--- a/c++/src/H5Group.cpp
+++ b/c++/src/H5Group.cpp
@@ -99,33 +99,11 @@ Group::Group(const hid_t existing_id) : H5Object()
 ///		is a datatype that has been named by DataType::commit.
 // Programmer	Binh-Minh Ribler - Oct, 2006
 //--------------------------------------------------------------------------
-Group::Group(H5Object& obj, const void* ref, H5R_type_t ref_type) : H5Object()
+Group::Group(const H5Location& loc, const void* ref, H5R_type_t ref_type, const PropList& plist) : H5Object(), id(0)
 {
-    try {
-	id = p_dereference(obj.getId(), ref, ref_type);
-    } catch (ReferenceException deref_error) {
-	throw ReferenceException("Group constructor - located by an H5Object",
-		deref_error.getDetailMsg());
-    }
-}
-
-//--------------------------------------------------------------------------
-// Function:	Group overload constructor - dereference
-///\brief	Given a reference, ref, to an hdf5 group, creates a Group object
-///\param	h5file - IN: Location referenced object is in
-///\param	ref - IN: Reference pointer
-///\param	ref_type - IN: Reference type - default to H5R_OBJECT
-///\exception	H5::ReferenceException
-// Programmer	Binh-Minh Ribler - Oct, 2006
-//--------------------------------------------------------------------------
-Group::Group(H5File& h5file, const void* ref, H5R_type_t ref_type) : H5Object()
-{
-    try {
-	id = p_dereference(h5file.getId(), ref, ref_type);
-    } catch (ReferenceException deref_error) {
-	throw ReferenceException("Group constructor - located by an H5File",
-		deref_error.getDetailMsg());
-    }
+     /* H5Location::dereference(loc, ref, ref_type, plist);
+ */ 
+    id = H5Location::p_dereference(loc.getId(), ref, ref_type, plist, "constructor - by dereference");
 }
 
 //--------------------------------------------------------------------------
@@ -137,14 +115,17 @@ Group::Group(H5File& h5file, const void* ref, H5R_type_t ref_type) : H5Object()
 ///\exception	H5::ReferenceException
 // Programmer	Binh-Minh Ribler - Oct, 2006
 //--------------------------------------------------------------------------
-Group::Group(Attribute& attr, const void* ref, H5R_type_t ref_type) : H5Object()
+Group::Group(const Attribute& attr, const void* ref, H5R_type_t ref_type, const PropList& plist) : H5Object(), id(0)
 {
+    id = H5Location::p_dereference(attr.getId(), ref, ref_type, plist, "constructor - by dereference");
+/*
     try {
-	id = p_dereference(attr.getId(), ref, ref_type);
+	id = p_dereference(attr.getId(), ref, ref_type, plist);
     } catch (ReferenceException deref_error) {
 	throw ReferenceException("Group constructor - located by an Attribute",
 		deref_error.getDetailMsg());
     }
+*/
 }
 
 //--------------------------------------------------------------------------
diff --git a/c++/src/H5Group.h b/c++/src/H5Group.h
index 3b53293..4003c21 100644
--- a/c++/src/H5Group.h
+++ b/c++/src/H5Group.h
@@ -26,9 +26,6 @@ class H5_DLLCPP Group : public H5Object, public CommonFG {
 	// Close this group.
 	virtual void close();
 
-	// Retrieves a dataspace with the region pointed to selected.
-	DataSpace getRegion(void *ref, H5R_type_t ref_type = H5R_DATASET_REGION) const;
-
 	///\brief Returns this class name.
 	virtual H5std_string fromClass () const { return("Group"); }
 
@@ -39,9 +36,10 @@ class H5_DLLCPP Group : public H5Object, public CommonFG {
 	virtual hid_t getLocId() const;
 
 	// Creates a group by way of dereference.
-	Group(H5Object& obj, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
-        Group(H5File& h5file, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
-        Group(Attribute& attr, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	Group(const H5Location& loc, const void* ref, H5R_type_t ref_type = H5R_OBJECT, const PropList& plist = PropList::DEFAULT);
+         /* Group(H5File& h5file, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
+ */ 
+        Group(const Attribute& attr, const void* ref, H5R_type_t ref_type = H5R_OBJECT, const PropList& plist = PropList::DEFAULT);
 
 	// default constructor
 	Group();
diff --git a/c++/src/H5IdComponent.cpp b/c++/src/H5IdComponent.cpp
index 4a997ab..c60d05c 100644
--- a/c++/src/H5IdComponent.cpp
+++ b/c++/src/H5IdComponent.cpp
@@ -144,6 +144,8 @@ int IdComponent::getCounter() const
 //--------------------------------------------------------------------------
 H5I_type_t IdComponent::getHDFObjType(const hid_t obj_id)
 {
+    if (obj_id == 0)
+	return H5I_BADID; // invalid
     H5I_type_t id_type = H5Iget_type(obj_id);
     if (id_type <= H5I_BADID || id_type >= H5I_NTYPES)
 	return H5I_BADID; // invalid
@@ -269,7 +271,7 @@ IdComponent::IdComponent() {}
 // Description:
 // 		This function is protected so that the user applications can
 // 		only have access to its code via allowable classes, namely,
-// 		H5File and H5Object subclasses.
+// 		Attribute and H5Location subclasses.
 // Programmer	Binh-Minh Ribler - Jul, 2004
 //--------------------------------------------------------------------------
 H5std_string IdComponent::p_get_file_name() const
@@ -314,6 +316,9 @@ H5std_string IdComponent::p_get_file_name() const
 //--------------------------------------------------------------------------
 bool IdComponent::p_valid_id(const hid_t obj_id)
 {
+    if (obj_id == 0)
+	return false;
+
     H5I_type_t id_type = H5Iget_type(obj_id);
     if (id_type <= H5I_BADID || id_type >= H5I_NTYPES)
 	return false;
diff --git a/c++/src/H5Location.cpp b/c++/src/H5Location.cpp
index fcf7ff4..22db85c 100644
--- a/c++/src/H5Location.cpp
+++ b/c++/src/H5Location.cpp
@@ -55,17 +55,17 @@ extern "C" herr_t userAttrOpWrpr(hid_t loc_id, const char *attr_name,
 }
 
 //--------------------------------------------------------------------------
-// Function:    H5Location default constructor (protected)
-// Programmer   Binh-Minh Ribler - 2000
+// Function:	H5Location default constructor (protected)
+// Programmer	Binh-Minh Ribler - 2000
 //--------------------------------------------------------------------------
-H5Location::H5Location() : IdComponent(0) {}
+H5Location::H5Location() : IdComponent() {}
 
 //--------------------------------------------------------------------------
-// Function:    H5Location overloaded constructor (protected)
-// Purpose      Creates an H5Location object using the id of an existing HDF5
-//              object.
-// Parameters   object_id - IN: Id of an existing HDF5 object
-// Programmer   Binh-Minh Ribler - 2000
+// Function:	H5Location overloaded constructor (protected)
+// Purpose	Creates an H5Location object using the id of an existing HDF5
+//		object.
+// Parameters	object_id - IN: Id of an existing HDF5 object
+// Programmer	Binh-Minh Ribler - 2000
 //--------------------------------------------------------------------------
 H5Location::H5Location(const hid_t object_id) : IdComponent(object_id) {}
 
@@ -342,7 +342,7 @@ void H5Location::renameAttr(const H5std_string& oldname, const H5std_string& new
 ///		which can be either of these values:
 ///		\li \c H5F_SCOPE_GLOBAL - Flushes the entire virtual file
 ///		\li \c H5F_SCOPE_LOCAL - Flushes only the specified file
-///\exception	H5::FileIException
+///\exception	H5::Exception
 ///\par Description
 ///		This location is used to identify the file to be flushed.
 // Programmer	Binh-Minh Ribler - 2012
@@ -355,7 +355,7 @@ void H5Location::flush(H5F_scope_t scope) const
    herr_t ret_value = H5Fflush(getId(), scope);
    if( ret_value < 0 )
    {
-      throw FileIException(inMemFunc("flush"), "H5Fflush failed");
+      throw Exception(inMemFunc("flush"), "H5Fflush failed");
    }
 }
 
@@ -376,41 +376,199 @@ H5std_string H5Location::getFileName() const
    }
 }
 
+//--------------------------------------------------------------------------
+// Function:	H5Location::setComment
+///\brief	Sets or resets the comment for an object specified by its name.
+///\param	name  - IN: Name of the object
+///\param	comment - IN: New comment
+///\exception	H5::Exception
+///\par	Description
+///		If \a comment is an empty string or a null pointer, the comment
+///		message is removed from the object.
+///		Comments should be relatively short, null-terminated, ASCII
+///		strings.  They can be attached to any object that has an
+///		object header, e.g., data sets, groups, named data types,
+///		and data spaces, but not symbolic links.
+// Programmer	Binh-Minh Ribler - 2000 (moved from CommonFG, Sep 2013)
+// Modification
+//	2007: QAK modified to use H5O APIs; however the first parameter is
+//		no longer just file or group, this function should be moved
+//		to another class to accommodate attribute, dataset, and named
+//		datatype. - BMR
+//--------------------------------------------------------------------------
+void H5Location::setComment(const char* name, const char* comment) const
+{
+   herr_t ret_value = H5Oset_comment_by_name(getId(), name, comment, H5P_DEFAULT);
+   if( ret_value < 0 )
+      throw Exception(inMemFunc("setComment"), "H5Oset_comment_by_name failed");
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Location::setComment
+///\brief	This is an overloaded member function, provided for convenience.
+///		It differs from the above function in that it takes an
+///		\c H5std_string for \a name and \a comment.
+// Programmer	Binh-Minh Ribler - 2000 (moved from CommonFG, Sep 2013)
+//--------------------------------------------------------------------------
+void H5Location::setComment(const H5std_string& name, const H5std_string& comment) const
+{
+   setComment(name.c_str(), comment.c_str());
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Location::setComment
+///\brief	This is an overloaded member function, provided for convenience.
+///		It differs from the above function in that it doesn't take
+///		an object name.
+// Programmer	Binh-Minh Ribler - Sep 2013
+// Modification
+//--------------------------------------------------------------------------
+void H5Location::setComment(const char* comment) const
+{
+   herr_t ret_value = H5Oset_comment_by_name(getId(), ".", comment, H5P_DEFAULT);
+   if( ret_value < 0 )
+      throw Exception(inMemFunc("setComment"), "H5Oset_comment_by_name failed");
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Location::setComment
+///\brief	This is an overloaded member function, provided for convenience.
+///		It differs from the above function in that it takes an
+///		\c H5std_string for \a comment.
+// Programmer	Binh-Minh Ribler - Sep 2013
+//--------------------------------------------------------------------------
+void H5Location::setComment(const H5std_string& comment) const
+{
+   setComment(comment.c_str());
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Location::removeComment
+///\brief	Removes the comment from an object specified by its name.
+///\param	name  - IN: Name of the object
+///\exception	H5::Exception
+// Programmer	Binh-Minh Ribler - May 2005 (moved from CommonFG, Sep 2013)
+//	2007: QAK modified to use H5O APIs; however the first parameter is
+//		no longer just file or group, this function should be moved
+//		to another class to accommodate attribute, dataset, and named
+//		datatype. - BMR
+//--------------------------------------------------------------------------
+void H5Location::removeComment(const char* name) const
+{
+   herr_t ret_value = H5Oset_comment_by_name(getId(), name, NULL, H5P_DEFAULT);
+   if( ret_value < 0 )
+      throw Exception(inMemFunc("removeComment"), "H5Oset_comment_by_name failed");
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Location::removeComment
+///\brief	This is an overloaded member function, provided for convenience.
+///		It differs from the above function in that it takes an
+///		\c H5std_string for \a name.
+// Programmer	Binh-Minh Ribler - May 2005 (moved from CommonFG, Sep 2013)
+//--------------------------------------------------------------------------
+void H5Location::removeComment(const H5std_string& name) const
+{
+   removeComment (name.c_str());
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Location::getComment
+///\brief	Retrieves comment for the specified object and its comment's
+///		length.
+///\param	name  - IN: Name of the object
+///\param	bufsize - IN: Length of the comment to retrieve
+///\return	Comment string
+///\exception	H5::Exception
+// Programmer	Binh-Minh Ribler - 2000 (moved from CommonFG, Sep 2013)
+//	2007: QAK modified to use H5O APIs; however the first parameter is
+//		no longer just file or group, this function should be moved
+//		to another class to accommodate attribute, dataset, and named
+//		datatype. - BMR
+//--------------------------------------------------------------------------
+H5std_string H5Location::getComment(const char* name, size_t bufsize) const
+{
+   // bufsize is default to 256
+   // temporary variable
+   hid_t loc_id = getId();   // temporary variable
+
+   // temporary C-string for the object's comment; bufsize already including
+   // null character
+   char* comment_C = new char[bufsize];
+   ssize_t ret_value = H5Oget_comment_by_name(loc_id, name, comment_C, bufsize, H5P_DEFAULT);
+
+   // if the actual length of the comment is longer than bufsize and bufsize
+   // was the default value, i.e., not given by the user, then call
+   // H5Oget_comment_by_name again with the correct value.
+   // If the call to H5Oget_comment_by_name returned an error, skip this block
+   // and throw an exception below.
+   if (ret_value >= 0 && (size_t)ret_value > bufsize && bufsize == 256)
+   {
+	size_t new_size = ret_value;
+	delete []comment_C;
+	comment_C = new char[new_size];	// new_size including null terminator
+	ret_value = H5Oget_comment_by_name(loc_id, name, comment_C, new_size, H5P_DEFAULT);
+   }
+
+   // if H5Oget_comment_by_name returns SUCCEED, return the string comment,
+   // otherwise, throw an exception
+   if (ret_value < 0) {
+       delete []comment_C;
+       throw Exception(inMemFunc("getComment"), "H5Oget_comment_by_name failed");
+   }
+
+   H5std_string comment = H5std_string(comment_C);
+   delete []comment_C;
+   return (comment);
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Location::getComment
+///\brief	This is an overloaded member function, provided for convenience.
+///		It differs from the above function in that it takes an
+///		\c H5std_string for \a name.
+// Programmer	Binh-Minh Ribler - 2000 (moved from CommonFG, Sep 2013)
+//--------------------------------------------------------------------------
+H5std_string H5Location::getComment(const H5std_string& name, size_t bufsize) const
+{
+   return(getComment(name.c_str(), bufsize));
+}
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
 
 //--------------------------------------------------------------------------
-// Function:    H5Location::p_reference (protected)
-// Purpose      Creates a reference to an HDF5 object or a dataset region.
+// Function:	H5Location::p_reference (protected)
+// Purpose	Creates a reference to an HDF5 object or a dataset region.
 // Parameters
-//              name - IN: Name of the object to be referenced
-//              dataspace - IN: Dataspace with selection
-//              ref_type - IN: Type of reference; default to \c H5R_DATASET_REGION
-// Exception    H5::IdComponentException
-// Programmer   Binh-Minh Ribler - May, 2004
+//		name - IN: Name of the object to be referenced
+//		dataspace - IN: Dataspace with selection
+//		ref_type - IN: Type of reference; default to \c H5R_DATASET_REGION
+// Exception	H5::IdComponentException
+// Programmer	Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
 void H5Location::p_reference(void* ref, const char* name, hid_t space_id, H5R_type_t ref_type) const
 {
    herr_t ret_value = H5Rcreate(ref, getId(), name, ref_type, space_id);
    if (ret_value < 0)
    {
-      throw ReferenceException("", "H5Rcreate failed");
+      throw ReferenceException(inMemFunc("reference"), "H5Rcreate failed");
    }
 }
 
 #endif // DOXYGEN_SHOULD_SKIP_THIS
 
 //--------------------------------------------------------------------------
-// Function:    H5Location::reference
-///\brief       Creates a reference to an HDF5 object or a dataset region.
-///\param       ref - IN: Reference pointer
-///\param       name - IN: Name of the object to be referenced
-///\param       dataspace - IN: Dataspace with selection
-///\param       ref_type - IN: Type of reference to query, valid values are:
+// Function:	H5Location::reference
+///\brief	Creates a reference to an HDF5 object or a dataset region.
+///\param	ref - IN: Reference pointer
+///\param	name - IN: Name of the object to be referenced
+///\param	dataspace - IN: Dataspace with selection
+///\param	ref_type - IN: Type of reference to query, valid values are:
 ///		\li \c H5R_OBJECT         - Reference is an object reference.
 ///		\li \c H5R_DATASET_REGION - Reference is a dataset region
 ///			reference. - this is the default
-///\exception   H5::ReferenceException
-// Programmer   Binh-Minh Ribler - May, 2004
+///\exception	H5::ReferenceException
+///\notes	This method is more suitable for a dataset region reference.
+// Programmer	Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
 void H5Location::reference(void* ref, const char* name, const DataSpace& dataspace, H5R_type_t ref_type) const
 {
@@ -418,46 +576,76 @@ void H5Location::reference(void* ref, const char* name, const DataSpace& dataspa
       p_reference(ref, name, dataspace.getId(), ref_type);
    }
    catch (ReferenceException E) {
-      throw ReferenceException("H5Location::reference", E.getDetailMsg());
+      throw ReferenceException(inMemFunc("reference"), E.getDetailMsg());
    }
 }
 
 //--------------------------------------------------------------------------
-// Function:    H5Location::reference
-///\brief       This is an overloaded function, provided for your convenience.
-///             It differs from the above function in that it only creates
-///             a reference to an HDF5 object, not to a dataset region.
-///\param       ref - IN: Reference pointer
-///\param       name - IN: Name of the object to be referenced - \c char pointer
-///\exception   H5::ReferenceException
-///\par Description
-//              This function passes H5R_OBJECT and -1 to the protected
-//              function for it to pass to the C API H5Rcreate
-//              to create a reference to the named object.
-// Programmer   Binh-Minh Ribler - May, 2004
+// Function:	H5Location::reference
+///\brief	This is an overloaded member function, provided for convenience.
+///		It differs from the above function in that it takes an
+///		\c H5std_string for \a name.
+///\param	ref - IN: Reference pointer
+///\param	name - IN: Name of the object to be referenced
+///\param	dataspace - IN: Dataspace with selection
+///\param	ref_type - IN: Type of reference to query, valid values are:
+///		\li \c H5R_OBJECT         - Reference is an object reference.
+///		\li \c H5R_DATASET_REGION - Reference is a dataset region
+///			reference. - this is the default
+///\exception	H5::ReferenceException
+///\notes	This method is more suitable for a dataset region reference.
+// Programmer	Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
-void H5Location::reference(void* ref, const char* name) const
+void H5Location::reference(void* ref, const H5std_string& name, const DataSpace& dataspace, H5R_type_t ref_type) const
 {
    try {
-      p_reference(ref, name, -1, H5R_OBJECT);
+      p_reference(ref, name.c_str(), dataspace.getId(), ref_type);
    }
    catch (ReferenceException E) {
-      throw ReferenceException("H5Location::reference", E.getDetailMsg());
+      throw ReferenceException(inMemFunc("reference"), E.getDetailMsg());
    }
 }
 
 //--------------------------------------------------------------------------
-// Function:    H5Location::reference
-///\brief       This is an overloaded function, provided for your convenience.
-///             It differs from the above function in that it takes an
-///             \c H5std_string for the object's name.
-///\param       ref - IN: Reference pointer
-///\param       name - IN: Name of the object to be referenced - \c H5std_string
-// Programmer   Binh-Minh Ribler - May, 2004
+// Function:	H5Location::reference
+///\brief	This is an overloaded function, provided for your convenience.
+///		It differs from the above function in that it does not take
+///		a DataSpace object and the reference type must be specified.
+///\param	ref - IN: Reference pointer
+///\param	name - IN: Name of the object to be referenced
+///\param	ref_type - IN: Type of reference to query, valid values are:
+///		\li \c H5R_OBJECT         - Reference is an object reference.
+///		\li \c H5R_DATASET_REGION - Reference is a dataset region
+///\exception	H5::ReferenceException
+///\notes	This method is more suitable for an object reference.
+// Programmer	Binh-Minh Ribler - May, 2004
+//--------------------------------------------------------------------------
+void H5Location::reference(void* ref, const char* name, H5R_type_t ref_type) const
+{
+   try {
+      p_reference(ref, name, -1, ref_type);
+   }
+   catch (ReferenceException E) {
+      throw ReferenceException(inMemFunc("reference"), E.getDetailMsg());
+   }
+}
+
+//--------------------------------------------------------------------------
+// Function:	H5Location::reference
+///\brief	This is an overloaded function, provided for your convenience.
+///		It differs from the above function in that it takes an
+///		\c H5std_string for the object's name.
+///\param	ref - IN: Reference pointer
+///\param	name - IN: Name of the object to be referenced - \c H5std_string
+///\param	ref_type - IN: Type of reference to query, valid values are:
+///		\li \c H5R_OBJECT         - Reference is an object reference.
+///		\li \c H5R_DATASET_REGION - Reference is a dataset region
+///\notes	This method is more suitable for an object reference.
+// Programmer	Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
-void H5Location::reference(void* ref, const H5std_string& name) const
+void H5Location::reference(void* ref, const H5std_string& name, H5R_type_t ref_type) const
 {
-   reference(ref, name.c_str());
+   reference(ref, name.c_str(), ref_type);
 }
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
@@ -475,16 +663,20 @@ void H5Location::reference(void* ref, const H5std_string& name) const
 //	May 2008 - BMR
 //		Moved from IdComponent.
 //--------------------------------------------------------------------------
-hid_t H5Location::p_dereference(hid_t loc_id, const void* ref, H5R_type_t ref_type)
+hid_t H5Location::p_dereference(hid_t loc_id, const void* ref, H5R_type_t ref_type, const PropList& plist, const char* from_func)
 {
-   hid_t temp_id;
-   temp_id = H5Rdereference2(loc_id, H5P_DEFAULT, ref_type, ref);
+   hid_t plist_id;
+   if (p_valid_id(plist.getId()))
+	plist_id = plist.getId();
+   else
+	plist_id = H5P_DEFAULT;
+
+   hid_t temp_id = H5Rdereference2(loc_id, plist_id, ref_type, ref);
    if (temp_id < 0)
    {
-      throw ReferenceException("", "H5Rdereference failed");
+      throw ReferenceException(inMemFunc(from_func), "H5Rdereference failed");
    }
 
-   // No failure, set id to the object
    return(temp_id);
 }
 #endif // DOXYGEN_SHOULD_SKIP_THIS
@@ -496,45 +688,14 @@ hid_t H5Location::p_dereference(hid_t loc_id, const void* ref, H5R_type_t ref_ty
 ///\param	ref - IN: Reference pointer
 ///\param	ref_type - IN: Reference type
 ///\exception	H5::ReferenceException
-// Programmer   Binh-Minh Ribler - Oct, 2006
-// Modification
-//	May, 2008
-//		Corrected missing parameters. - BMR
-//--------------------------------------------------------------------------
-void H5Location::dereference(H5Object& obj, const void* ref, H5R_type_t ref_type)
-{
-   hid_t temp_id;
-   try {
-      temp_id = p_dereference(obj.getId(), ref, ref_type);
-   }
-   catch (ReferenceException E) {
-      throw ReferenceException("H5Location::dereference - located by object", E.getDetailMsg());
-   }
-   p_setId(temp_id);
-}
-
-//--------------------------------------------------------------------------
-// Function:	H5Location::dereference
-///\brief	Dereferences a reference into an HDF5 object, given an HDF5 file.
-///\param	h5file - IN: HDF5 file specifying the location of the referenced object
-///\param	ref - IN: Reference pointer
-///\param	ref_type - IN: Reference type
-///\exception	H5::ReferenceException
-// Programmer   Binh-Minh Ribler - Oct, 2006
+// Programmer	Binh-Minh Ribler - Oct, 2006
 // Modification
 //	May, 2008
 //		Corrected missing parameters. - BMR
 //--------------------------------------------------------------------------
-void H5Location::dereference(H5File& h5file, const void* ref, H5R_type_t ref_type)
+void H5Location::dereference(const H5Location& loc, const void* ref, H5R_type_t ref_type, const PropList& plist)
 {
-   hid_t temp_id;
-   try {
-      temp_id = p_dereference(h5file.getId(), ref, ref_type);
-   }
-   catch (ReferenceException E) {
-      throw ReferenceException("H5Location::dereference - located by file", E.getDetailMsg());
-   }
-   p_setId(temp_id);
+   p_setId(p_dereference(loc.getId(), ref, ref_type, plist, "dereference"));
 }
 
 //--------------------------------------------------------------------------
@@ -544,21 +705,14 @@ void H5Location::dereference(H5File& h5file, const void* ref, H5R_type_t ref_typ
 ///\param	ref - IN: Reference pointer
 ///\param	ref_type - IN: Reference type
 ///\exception	H5::ReferenceException
-// Programmer   Binh-Minh Ribler - Oct, 2006
+// Programmer	Binh-Minh Ribler - Oct, 2006
 // Modification
 //	May, 2008
 //		Corrected missing parameters. - BMR
 //--------------------------------------------------------------------------
-void H5Location::dereference(Attribute& attr, const void* ref, H5R_type_t ref_type)
+void H5Location::dereference(const Attribute& attr, const void* ref, H5R_type_t ref_type, const PropList& plist)
 {
-   hid_t temp_id;
-   try {
-      temp_id = p_dereference(attr.getId(), ref, ref_type);
-   }
-   catch (ReferenceException E) {
-      throw ReferenceException("H5Location::dereference - located by attribute", E.getDetailMsg());
-   }
-   p_setId(temp_id);
+   p_setId(p_dereference(attr.getId(), ref, ref_type, plist, "dereference"));
 }
 
 #ifndef H5_NO_DEPRECATED_SYMBOLS
@@ -587,26 +741,26 @@ H5G_obj_t H5Location::getObjType(void *ref, H5R_type_t ref_type) const
       return(p_get_obj_type(ref, ref_type));
    }
    catch (ReferenceException E) {
-      throw ReferenceException("H5Location::getObjType", E.getDetailMsg());
+      throw ReferenceException(inMemFunc("getObjType"), E.getDetailMsg());
    }
 }
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
 //--------------------------------------------------------------------------
-// Function:    H5Location::p_get_obj_type (protected)
-// Purpose      Retrieves the type of object that an object reference points to.
+// Function:	H5Location::p_get_obj_type (protected)
+// Purpose	Retrieves the type of object that an object reference points to.
 // Parameters
-//              ref      - IN: Reference to query
-//              ref_type - IN: Type of reference to query
-// Return       An object type, which can be one of the following:
-//                      H5G_UNKNOWN \tFailure occurs (-1)
-//                      H5G_GROUP \tObject is a group.
-//                      H5G_DATASET \tObject is a dataset.
-//                      H5G_TYPE Object \tis a named datatype.
-//                      H5G_LINK \tObject is a symbolic link.
-//                      H5G_UDLINK \tObject is a user-defined link.
-// Exception    H5::ReferenceException
-// Programmer   Binh-Minh Ribler - May, 2004
+//		ref      - IN: Reference to query
+//		ref_type - IN: Type of reference to query
+// Return	An object type, which can be one of the following:
+//			H5G_UNKNOWN \tFailure occurs (-1)
+//			H5G_GROUP \tObject is a group.
+//			H5G_DATASET \tObject is a dataset.
+//			H5G_TYPE Object \tis a named datatype.
+//			H5G_LINK \tObject is a symbolic link.
+//			H5G_UDLINK \tObject is a user-defined link.
+// Exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
 H5G_obj_t H5Location::p_get_obj_type(void *ref, H5R_type_t ref_type) const
 {
@@ -614,7 +768,7 @@ H5G_obj_t H5Location::p_get_obj_type(void *ref, H5R_type_t ref_type) const
 
    if (obj_type == H5G_UNKNOWN)
    {
-      throw ReferenceException("", "H5Rget_obj_type1 failed");
+      throw ReferenceException(inMemFunc("getObjType"), "H5Rget_obj_type1 failed");
    }
    return(obj_type);
 }
@@ -622,20 +776,20 @@ H5G_obj_t H5Location::p_get_obj_type(void *ref, H5R_type_t ref_type) const
 #endif /* H5_NO_DEPRECATED_SYMBOLS */
 
 //--------------------------------------------------------------------------
-// Function:    H5Location::getRefObjType
-///\brief       Retrieves the type of object that an object reference points to.
-///\param       ref      - IN: Reference to query
-///\param       ref_type - IN: Type of reference to query, valid values are:
-///             \li \c H5R_OBJECT         - Reference is an object reference.
-///             \li \c H5R_DATASET_REGION - Reference is a dataset region reference.
-///\return      An object type, which can be one of the following:
-///             \li \c H5O_TYPE_UNKNOWN	- Unknown object type (-1)
-///             \li \c H5O_TYPE_GROUP	- Object is a group
-///             \li \c H5O_TYPE_DATASET	- Object is a dataset
-///             \li \c H5O_TYPE_NAMED_DATATYPE - Object is a named datatype
-///             \li \c H5O_TYPE_NTYPES	- Number of different object types
-///\exception   H5::ReferenceException
-// Programmer   Binh-Minh Ribler - May, 2004
+// Function:	H5Location::getRefObjType
+///\brief	Retrieves the type of object that an object reference points to.
+///\param	ref      - IN: Reference to query
+///\param	ref_type - IN: Type of reference to query, valid values are:
+///		\li \c H5R_OBJECT         - Reference is an object reference.
+///		\li \c H5R_DATASET_REGION - Reference is a dataset region reference.
+///\return	An object type, which can be one of the following:
+///		\li \c H5O_TYPE_UNKNOWN	- Unknown object type (-1)
+///		\li \c H5O_TYPE_GROUP	- Object is a group
+///		\li \c H5O_TYPE_DATASET	- Object is a dataset
+///		\li \c H5O_TYPE_NAMED_DATATYPE - Object is a named datatype
+///		\li \c H5O_TYPE_NTYPES	- Number of different object types
+///\exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
 H5O_type_t H5Location::getRefObjType(void *ref, H5R_type_t ref_type) const
 {
@@ -643,25 +797,25 @@ H5O_type_t H5Location::getRefObjType(void *ref, H5R_type_t ref_type) const
       return(p_get_ref_obj_type(ref, ref_type));
    }
    catch (ReferenceException E) {
-      throw ReferenceException("H5Location::getRefObjType", E.getDetailMsg());
+      throw ReferenceException(inMemFunc("getRefObjType"), E.getDetailMsg());
    }
 }
 
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
 //--------------------------------------------------------------------------
-// Function:    H5Location::p_get_ref_obj_type (protected)
-// Purpose      Retrieves the type of object that an object reference points to.
+// Function:	H5Location::p_get_ref_obj_type (protected)
+// Purpose	Retrieves the type of object that an object reference points to.
 // Parameters
-//              ref      - IN: Reference to query
-//              ref_type - IN: Type of reference to query
-// Return       An object type, which can be one of the following:
+//		ref      - IN: Reference to query
+//		ref_type - IN: Type of reference to query
+// Return	An object type, which can be one of the following:
 //			H5O_TYPE_UNKNOWN	- Unknown object type (-1)
 //			H5O_TYPE_GROUP		- Object is a group
 //			H5O_TYPE_DATASET	- Object is a dataset
 //			H5O_TYPE_NAMED_DATATYPE - Object is a named datatype
 //			H5O_TYPE_NTYPES		- Number of object types
-// Exception    H5::ReferenceException
-// Programmer   Binh-Minh Ribler - May, 2004
+// Exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
 H5O_type_t H5Location::p_get_ref_obj_type(void *ref, H5R_type_t ref_type) const
 {
@@ -670,31 +824,36 @@ H5O_type_t H5Location::p_get_ref_obj_type(void *ref, H5R_type_t ref_type) const
 
    if (obj_type == H5O_TYPE_UNKNOWN || obj_type >= H5O_TYPE_NTYPES)
    {
-      throw ReferenceException("", "H5Rget_obj_type2 failed");
+      throw ReferenceException(inMemFunc("getRefObjType"), "H5Rget_obj_type2 failed");
    }
    return(obj_type);
 }
 
 
 //--------------------------------------------------------------------------
-// Function:    H5Location::p_get_region (protected)
-// Purpose      Retrieves a dataspace with the region pointed to selected.
-// Parameters
-//              ref_type - IN: Type of reference to get region of - default
-//                              to H5R_DATASET_REGION
-//              ref      - IN: Reference to get region of
-// Return       Dataspace id
-// Exception    H5::ReferenceException
-// Programmer   Binh-Minh Ribler - May, 2004
+// Function:	H5Location::getRegion
+///\brief	Retrieves a dataspace with the region pointed to selected.
+///\param	ref	 - IN: Reference to get region of
+///\param	ref_type - IN: Type of reference to get region of - default
+//				to H5R_DATASET_REGION
+///\return	DataSpace object
+///\exception	H5::ReferenceException
+// Programmer	Binh-Minh Ribler - May, 2004
 //--------------------------------------------------------------------------
-hid_t H5Location::p_get_region(void *ref, H5R_type_t ref_type) const
+DataSpace H5Location::getRegion(void *ref, H5R_type_t ref_type) const
 {
    hid_t space_id = H5Rget_region(getId(), ref_type, ref);
    if (space_id < 0)
    {
-      throw ReferenceException("", "H5Rget_region failed");
+      throw ReferenceException(inMemFunc("getRegion"), "H5Rget_region failed");
+   }
+   try {
+      DataSpace dataspace(space_id);
+      return(dataspace);
+   }
+   catch (DataSpaceIException E) {
+      throw ReferenceException(inMemFunc("getRegion"), E.getDetailMsg());
    }
-   return(space_id);
 }
 
 
diff --git a/c++/src/H5Location.h b/c++/src/H5Location.h
index 1f54439..50278db 100644
--- a/c++/src/H5Location.h
+++ b/c++/src/H5Location.h
@@ -36,12 +36,12 @@ typedef void (*attr_operator_t)( H5Location& loc/*in*/,
 
 class UserData4Aiterate { // user data for attribute iteration
    public:
-        attr_operator_t op;
-        void* opData;
-        H5Location* location;
+	attr_operator_t op;
+	void* opData;
+	H5Location* location;
 };
 
-// An H5Location can be a file, group, dataset, named datatype, or attribute.
+// An H5Location can be a file, group, dataset, or committed datatype.
 
 class H5_DLLCPP H5Location : public IdComponent {
    public:
@@ -85,29 +85,49 @@ class H5_DLLCPP H5Location : public IdComponent {
 	bool attrExists(const char* name) const;
 	bool attrExists(const H5std_string& name) const;
 
+	// Renames the named attribute to a new name.
+	void renameAttr(const char* oldname, const char* newname) const;
+	void renameAttr(const H5std_string& oldname, const H5std_string& newname) const;
+
 	// Removes the named attribute from this location.
 	void removeAttr(const char* name) const;
 	void removeAttr(const H5std_string& name) const;
 
-	// Renames the named attribute to a new name.
-	void renameAttr(const char* oldname, const char* newname) const;
-	void renameAttr(const H5std_string& oldname, const H5std_string& newname) const;
+	// Sets the comment for an HDF5 object specified by its name.
+	void setComment(const char* name, const char* comment) const;
+	void setComment(const H5std_string& name, const H5std_string& comment) const;
+	void setComment(const char* comment) const;
+	void setComment(const H5std_string& comment) const;
+
+	// Retrieves comment for the HDF5 object specified by its name.
+	H5std_string getComment(const char* name, size_t bufsize=256) const;
+	H5std_string getComment(const H5std_string& name, size_t bufsize=256) const;
+
+	// Removes the comment for the HDF5 object specified by its name.
+	void removeComment(const char* name) const;
+	void removeComment(const H5std_string& name) const;
 
 	// Creates a reference to a named object or to a dataset region
 	// in this object.
+	void reference(void* ref, const char* name, 
+			H5R_type_t ref_type = H5R_OBJECT) const;
+	void reference(void* ref, const H5std_string& name,
+			H5R_type_t ref_type = H5R_DATASET_REGION) const;
 	void reference(void* ref, const char* name, const DataSpace& dataspace,
 			H5R_type_t ref_type = H5R_DATASET_REGION) const;
-	void reference(void* ref, const char* name) const;
-	void reference(void* ref, const H5std_string& name) const;
+	void reference(void* ref, const H5std_string& name, const DataSpace& dataspace,
+			H5R_type_t ref_type = H5R_DATASET_REGION) const;
 
 	// Open a referenced object whose location is specified by either
 	// a file, an HDF5 object, or an attribute.
-	void dereference(H5File& h5file, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
-	void dereference(H5Object& obj, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
-	void dereference(Attribute& attr, const void* ref, H5R_type_t ref_type = H5R_OBJECT);
+	void dereference(const H5Location& loc, const void* ref, H5R_type_t ref_type = H5R_OBJECT, const PropList& plist = PropList::DEFAULT);
+	void dereference(const Attribute& attr, const void* ref, H5R_type_t ref_type = H5R_OBJECT, const PropList& plist = PropList::DEFAULT);
 
-        ///\brief Returns an identifier. (pure virtual)
-        virtual hid_t getId() const = 0;
+	// Retrieves a dataspace with the region pointed to selected.
+	DataSpace getRegion(void *ref, H5R_type_t ref_type = H5R_DATASET_REGION) const;
+
+	///\brief Returns an identifier. (pure virtual)
+	virtual hid_t getId() const = 0;
 
    protected:
 #ifndef DOXYGEN_SHOULD_SKIP_THIS
@@ -124,7 +144,7 @@ class H5_DLLCPP H5Location : public IdComponent {
 	void p_reference(void* ref, const char* name, hid_t space_id, H5R_type_t ref_type) const;
 
 	// Dereferences a ref into an HDF5 id.
-	hid_t p_dereference(hid_t loc_id, const void* ref, H5R_type_t ref_type);
+	hid_t p_dereference(hid_t loc_id, const void* ref, H5R_type_t ref_type, const PropList& plist, const char* from_func);
 
 #ifndef H5_NO_DEPRECATED_SYMBOLS
 	// Retrieves the type of object that an object reference points to.
@@ -134,9 +154,6 @@ class H5_DLLCPP H5Location : public IdComponent {
 	// Retrieves the type of object that an object reference points to.
 	H5O_type_t p_get_ref_obj_type(void *ref, H5R_type_t ref_type) const;
 
-	// Retrieves a dataspace with the region pointed to selected.
-	hid_t p_get_region(void *ref, H5R_type_t ref_type) const;
-
 	// Noop destructor.
 	virtual ~H5Location();
 
diff --git a/c++/src/H5Object.cpp b/c++/src/H5Object.cpp
index b596092..1d96f2e 100644
--- a/c++/src/H5Object.cpp
+++ b/c++/src/H5Object.cpp
@@ -52,7 +52,6 @@ H5Object::H5Object() : H5Location() {}
 //--------------------------------------------------------------------------
 H5Object::H5Object( const hid_t object_id ) : H5Location( object_id ) {}
 
-
 //--------------------------------------------------------------------------
 // Function:	H5Object copy constructor
 ///\brief	Copy constructor: makes a copy of the original H5Object
diff --git a/c++/src/H5PropList.cpp b/c++/src/H5PropList.cpp
index c14d74f..9476d46 100644
--- a/c++/src/H5PropList.cpp
+++ b/c++/src/H5PropList.cpp
@@ -39,7 +39,7 @@ namespace H5 {
 //--------------------------------------------------------------------------
 ///\brief	Constant for default property.
 //--------------------------------------------------------------------------
-const PropList PropList::DEFAULT( H5P_DEFAULT );
+const PropList PropList::DEFAULT;
 
 //--------------------------------------------------------------------------
 // Function	Default constructor
@@ -74,6 +74,9 @@ PropList::PropList(const PropList& original) : IdComponent(original)
 //--------------------------------------------------------------------------
 PropList::PropList( const hid_t plist_id ) : IdComponent()
 {
+    if (plist_id == 0)
+	id = H5P_DEFAULT;
+
     H5I_type_t id_type = H5Iget_type(plist_id);
     switch (id_type) {
 	case H5I_GENPROP_CLS: