[svn-r25449] more UG updates.

2 files changed, 873 insertions, 876 deletions

diff --git a/docs/user_manual/main.pdf b/docs/user_manual/main.pdf
index 3fc319d..b1c2be6 100644
--- a/docs/user_manual/main.pdf
+++ b/docs/user_manual/main.pdf
diff --git a/docs/user_manual/plugin.tex b/docs/user_manual/plugin.tex
index 80439c0..280bcc8 100644
--- a/docs/user_manual/plugin.tex
+++ b/docs/user_manual/plugin.tex
@@ -192,195 +192,127 @@ Finally there are a set of functions for the file and general object
 plugin developers to implement. Those routines are mapped to a {\tt
   misc} callback in their respective class.
 
-\subsection{The Attribute Function Callbacks}
-The attribute API routines (H5A) allow HDF5 users to create and manage
-HDF5 attributes. All the H5A API routines that modify the HDF5
-container map to one of the attribute callback routines in this
-class that the plugin needs to implement:
+\subsection{The File Function Callbacks}
+The file API routines (H5F) allow HDF5 users to create and manage HDF5
+containers. All the H5F API routines that modify the HDF5 container
+map to one of the file callback routines in this class that the plugin
+needs to implement:
 
 \begin{lstlisting}
-typedef struct H5VL_attr_class_t {
-    void *(*create)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *attr_name, hid_t acpl_id, hid_t aapl_id, 
-        hid_t dxpl_id, void **req);
-
-    void *(*open)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *attr_name, hid_t aapl_id, hid_t dxpl_id, void **req);
-
-    herr_t (*read)(void *attr, hid_t mem_type_id, void *buf, 
-        hid_t dxpl_id, void **req);
+typedef struct H5VL_file_class_t {
+    void *(*create)(const char *name, unsigned flags, hid_t fcpl_id,
+        hid_t fapl_id, hid_t dxpl_id, void **req);
 
-    herr_t (*write)(void *attr, hid_t mem_type_id, const void *buf, 
+    void *(*open)(const char *name, unsigned flags, hid_t fapl_id, 
         hid_t dxpl_id, void **req);
 
-    herr_t (*iterate)(void *obj, H5VL_loc_params_t loc_params,
-        H5_index_t idx_type, H5_iter_order_t order, hsize_t *n, 
-        H5A_operator2_t  op, void *op_data, hid_t dxpl_id, void **req);
+    herr_t (*flush)(void *obj, H5VL_loc_params_t loc_params, 
+        H5F_scope_t scope, hid_t dxpl_id, void **req);
 
-    herr_t (*get)(void *obj, H5VL_attr_get_t get_type, hid_t dxpl_id, 
+    herr_t (*get)(void *obj, H5VL_file_get_t get_type, hid_t dxpl_id, 
         void **req, va_list arguments);
 
-    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *attr_name, hid_t dxpl_id, void **req);
-
-    herr_t (*close)(void *attr, hid_t dxpl_id, void **req);
-} H5VL_attr_class_t;
-\end{lstlisting}
-
-The {\tt create} callback in the attribute class should create an
-attribute object in the container of the location object and
-returns a pointer to the attribute structure containing information to
-access the attribute in future calls. 
-
-\textbf{Signature:}
-\begin{lstlisting}
-    void *(*create)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *attr_name, hid_t acpl_id, hid_t aapl_id, 
-        hid_t dxpl_id, void **req);
-\end{lstlisting}
-
-\textbf{Arguments:}\\
-\begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to an object where the attribute needs
-  to be created or where the look-up of the target object needs to
-  start.\\
-  {\tt loc\_params} & (IN): The location parameters as explained in
-  section~\ref{sec:map}.\\
-  {\tt attr\_name} & (IN): The name of the attribute to be created.\\
-  {\tt acpl\_id} & (IN): The attribute creation property list. It contains
-  all the attribute creation properties in addition to the attribute
-  datatype (an {\tt hid\_t}) and dataspace (an {\tt hid\_t}) that can
-  be retrieved with the properties, {\tt H5VL\_ATTR\_TYPE\_ID} and
-  {\tt H5VL\_ATTR\_SPACE\_ID}.\\
-  {\tt aapl\_id} & (IN): The attribute access property list.\\
-  {\tt dxpl\_id} & (IN): The data transfer property list.\\
-  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
-  operation created by the plugin.\\
-\end{tabular}
+    herr_t (*misc)(void *obj, H5VL_file_misc_t misc_type, 
+        hid_t dxpl_id, void **req, va_list arguments);
 
-The {\tt open} callback in the attribute class should open an
-attribute object in the container of the location object and returns a
-pointer to the attribute structure containing information to access
-the attribute in future calls. 
+    herr_t (*optional)(void *obj, H5VL_file_optional_t op_type, 
+        hid_t dxpl_id, void **req, va_list arguments);
 
-\textbf{Signature:}
-\begin{lstlisting}
-    void *(*open)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *attr_name, hid_t aapl_id, hid_t dxpl_id, void **req);
+    herr_t (*close) (void *file, hid_t dxpl_id, void **req);
+} H5VL_file_class_t;
 \end{lstlisting}
 
-\textbf{Arguments:}\\
-\begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to an object where the attribute needs to be
-  opened or where the look-up of the target object needs to start.\\
-  {\tt loc\_params} & (IN): The location parameters as explained in
-  section~\ref{sec:map}.\\
-  {\tt attr\_name} & (IN): The name of the attribute to be opened.\\
-  {\tt aapl\_id} & (IN): The attribute access property list.\\
-  {\tt dxpl\_id} & (IN): The data transfer property list.\\
-  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
-  operation created by the plugin.\\
-\end{tabular}
-
-The {\tt read} callback in the attribute class should read data from
-the attribute object and returns an {\tt herr\_t} indicating success or
-failure.
+The {\tt create} callback in the file class should create a container
+and returns a pointer to the file structure containing information to
+access the container in future calls.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*read)(void *attr, hid_t mem_type_id, void *buf, 
-        hid_t dxpl_id, void **req);
+    void *(*create)(const char *name, unsigned flags, hid_t fcpl_id,
+        hid_t fapl_id, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt attr} & (IN): Pointer to the attribute object.\\
-  {\tt mem\_type\_id} & (IN): The memory datatype of the attribute.\\
-  {\tt buf} & (OUT): Data buffer to be read into.\\
+  {\tt name} & (IN): The name of the container to be created.\\
+  {\tt flags} & (IN): The creation flags of the container.\\
+  {\tt fcpl\_id} & (IN): The file creation property list.\\
+  {\tt fapl\_id} & (IN): The file access property list.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt write} callback in the attribute class should write data to
-the attribute object and returns an {\tt herr\_t} indicating success or
-failure.
+The {\tt open} callback in the file class should open a container and
+returns a pointer to the file structure containing information to
+access the container in future calls.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*write)(void *attr, hid_t mem_type_id, const void *buf, 
+    void *(*open)(const char *name, unsigned flags, hid_t fapl_id, 
         hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt attr} & (IN): Pointer to the attribute object.\\
-  {\tt mem\_type\_id} & (IN): The memory datatype of the attribute.\\
-  {\tt buf} & (IN): Data buffer to be written.\\
+  {\tt name} & (IN): The name of the container to open.\\
+  {\tt flags} & (IN): The open flags of the container.\\
+  {\tt fapl\_id} & (IN): The file access property list.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt iterate} callback in the attribute class should iterate over
-the attributes in the container of the location object and call the
-user defined function on each one. It returns an {\tt herr\_t}
+The {\tt flush} callback in the file class should flush all buffers
+associated with the container to disk and returns an {\tt herr\_t}
 indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*iterate)(void *obj, H5VL_loc_params_t loc_params,
-        H5_index_t idx_type, H5_iter_order_t order, hsize_t *n, 
-        H5A_operator2_t  op, void *op_data, hid_t dxpl_id, void **req);
+    herr_t (*flush)(void *obj, H5VL_loc_params_t loc_params, 
+        H5F_scope_t scope, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to an object where the iteration needs
-  to happen or where the look-up of the target object needs to
-  start.\\
-  {\tt loc\_params} & (IN): The location parameters as
-  explained in section~\ref{sec:map}.\\
-  {\tt idx\_type} & (IN): Type of index.\\
-  {\tt order} & (IN): Order in which to iterate over index.\\
-  {\tt n} & (IN/OUT): Initial and return offset withing index.\\
-  {\tt op} & (IN): User-defined function to pass each
-  attribute to. \\
-  {\tt op\_data} & (IN/OUT): User data to pass through to and to be
-  returned by iterator operator function. \\
+  {\tt obj} & (IN): Pointer to a file or object in the file to be flushed.\\
+  {\tt loc\_params} & (IN): The location parameters as explained in
+  section~\ref{sec:map}. The type can be only {\tt
+    H5VL\_OBJECT\_BY\_SELF} in this callback. \\
+  {\tt scope} & (IN): The scope of the flushing action.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt get} callback in the attribute class should retrieve
-information about the attribute as specified in the {\tt get\_type}
+The {\tt get} callback in the file class should retrieve
+information about the container as specified in the {\tt get\_type}
 parameter.It returns an {\tt herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*get)(void *obj, H5VL_attr_get_t get_type, hid_t dxpl_id, 
+    herr_t (*get)(void *obj, H5VL_file_get_t get_type, hid_t dxpl_id, 
         void **req, va_list arguments);
 \end{lstlisting}
 
 The {\tt get\_type} argument is an {\tt enum}:
 \begin{lstlisting}
-/* types for all attr get API routines */
-typedef enum H5VL_attr_get_t {
-    H5VL_ATTR_EXISTS,           /* attribute exists?       */
-    H5VL_ATTR_GET_SPACE,        /* dataspace               */
-    H5VL_ATTR_GET_TYPE,         /* datatype                */
-    H5VL_ATTR_GET_ACPL,         /* creation property list  */
-    H5VL_ATTR_GET_NAME,         /* access property list    */
-    H5VL_ATTR_GET_STORAGE_SIZE, /* storage size            */
-    H5VL_ATTR_GET_INFO          /* offset                  */
-} H5VL_attr_get_t;
+/* types for all file get API routines */
+typedef enum H5VL_file_get_t {
+    H5VL_FILE_GET_FAPL,      /* file access property list   */
+    H5VL_FILE_GET_FCPL,      /* file creation property list */
+    H5VL_FILE_GET_INTENT,    /* file intent                 */
+    H5VL_FILE_GET_NAME,      /* file name                   */
+    H5VL_FILE_GET_OBJ_COUNT, /* object count in file        */
+    H5VL_FILE_GET_OBJ_IDS,   /* object ids in file          */
+    H5VL_OBJECT_GET_FILE
+} H5VL_file_get_t;
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt attr} & (IN): An attribute or location object where information
-  needs to be retrieved from.\\
+  {\tt obj} & (IN): The container or object where information needs to be
+  retrieved from.\\
   {\tt get\_type} & (IN): The type of the information to retrieve.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
@@ -394,250 +326,387 @@ depending on the {\tt get\_type} parameter. The following list shows
 the argument list, in-order, for each type:
 
 \begin{itemize}
-\item {\tt H5VL\_ATTR\_EXISTS}, to check if an attribute exists on a
-  particular object specified in {\tt obj}:
+\item {\tt H5VL\_FILE\_GET\_FCPL}, to retrieve the file creation
+  property list:
   \begin{enumerate}
-  \item {\tt H5VL\_loc\_params\_t loc\_params} (IN): The location parameters
-    explained in section~\ref{sec:map}.
-  \item {\tt char *attr\_name} (IN): the attribute name to check.
-  \item {\tt htri\_t *ret} (OUT): existence result, 0 if false, 1 if true.
+  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
+    file creation property list.
   \end{enumerate}
 
-\item {\tt H5VL\_ATTR\_GET\_SPACE}, to retrieve the dataspace of the
-  attribute specified in {\tt obj}:
+\item {\tt H5VL\_FILE\_GET\_FAPL}, to retrieve the file access
+  property list:
   \begin{enumerate}
   \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
-    attribute dataspace.
+    file access property list.
   \end{enumerate}
 
-\item {\tt H5VL\_ATTR\_GET\_TYPE}, to retrieve the datatype of the
-  attribute specified in {\tt obj}:
+\item {\tt H5VL\_FILE\_GET\_OBJ\_COUNT:}, to retrieve the object count
+  in the container:
   \begin{enumerate}
-  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
-    attribute datatype.
+  \item {\tt unsigned types} (IN): type of objects to look for.
+  \item {\tt ssize\_t *ret} (OUT): buffer for the object count.
   \end{enumerate}
 
-\item {\tt H5VL\_ATTR\_GET\_ACPL}, to retrieve the attribute creation
-  property list of the attribute specified in {\tt obj}:
+\item {\tt H5VL\_FILE\_GET\_OBJ\_IDS:}, to retrieve object identifiers
+  in the container:
   \begin{enumerate}
-  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
-    attribute creation property list.
+  \item {\tt unsigned types} (IN): type of objects to look for.
+  \item {\tt size\_t max\_objs} (IN): maximum number of objects to
+    open.
+  \item {\tt hid\_t *oid\_list} (OUT): buffer for the object identifiers.
+  \item {\tt ssize\_t *ret} (OUT): buffer for the object count.
   \end{enumerate}
 
-\item {\tt H5VL\_ATTR\_GET\_NAME}, to retrieve an attribute name on a
-  particular object specified in {\tt obj}:
+\item {\tt H5VL\_FILE\_GET\_INTENT}, get access intent of the
+  container:
   \begin{enumerate}
-  \item {\tt H5VL\_loc\_params\_t loc\_params} (IN): The location parameters
-    explained in section~\ref{sec:map}. The type could be either
-    {\tt H5VL\_OBJECT\_BY\_SELF} meaning {\tt obj} is the attribute,
-    or {\tt H5VL\_OBJECT\_BY\_IDX} meaning the attribute to retrieve
-    the name for should be looked up using the index information on
-    the object in {\tt obj} and the index information in {\tt loc\_params}.
-  \item {\tt size\_t buf\_size} (IN): the size of the buffer to store
-    the name in.
-  \item {\tt void *buf} (OUT): Buffer to store the name in.
-  \item {\tt ssize\_t *ret\_val} (OUT): return the actual size needed
-    to store the fill attribute name.
+  \item {\tt unsigned *ret} (OUT): buffer for the intent value.
   \end{enumerate}
 
-\item {\tt H5VL\_ATTR\_GET\_INFO}, to retrieve the attribute info:
+\item {\tt H5VL\_FILE\_GET\_NAME}, get container name an object
+  belongs to:
   \begin{enumerate}
-  \item {\tt H5VL\_loc\_params\_t loc\_params} (IN): The location parameters
-    explained in section~\ref{sec:map}. 
-  \item {\tt H5A\_info\_t *ainfo} (OUT): info structure to fill the
-    attribute info in.
+  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
+  \item {\tt size\_t size} (IN): size of the buffer for the file name.
+  \item {\tt char *name} (OUT): buffer for the file name.
+  \item {\tt ssize\_t *ret} (OUT): buffer for the entire size of the
+    file name.
   \end{enumerate}
 
-\item {\tt H5VL\_ATTR\_GET\_STORAGE\_SIZE}, to retrieve the storage
-  size of the attribute specified in {\tt obj}:
+\item {\tt H5VL\_OBJECT\_GET\_FILE}, get the container that the object
+  belongs to:
   \begin{enumerate}
-  \item {\tt hsize\_t *ret} (OUT): buffer for the storage size of
-    the attribute in the container.
+  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
+  \item {\tt void **ret} (OUT): pointer to the file structure returned
+    by the plugin.
   \end{enumerate}
-
 \end{itemize}
 
-The {\tt remove} callback in the attribute class should remove an
-attribute object in the container of the location object and returns
-an {\tt herr\_t} indicating success or failure.
+The {\tt misc} callback in the file class should execute some not very
+common operations on the container as specified in the {\tt
+  misc\_type} parameter. It returns an {\tt herr\_t} indicating
+success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *attr_name, hid_t dxpl_id, void **req);
+    herr_t (*misc)(void *obj, H5VL_file_misc_t misc_type, hid_t dxpl_id, 
+        void **req, va_list arguments);
+\end{lstlisting}
+
+The {\tt misc\_type} argument is an {\tt enum}:
+\begin{lstlisting}
+/* types for all file misc operations */
+typedef enum H5VL_file_misc_t {
+    H5VL_FILE_MOUNT,         /* H5Fmount                     */
+    H5VL_FILE_UNMOUNT,       /* H5Funmount                   */
+    H5VL_FILE_IS_ACCESSIBLE  /* is the container accessible? */
+} H5VL_file_misc_t;
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to an object where the attribute needs
-  to be removed or where the look-up of the target object needs to
-  start.\\
-  {\tt loc\_params} & (IN): The location parameters as explained in
-  section~\ref{sec:map}.\\
-  {\tt attr\_name} & (IN): The name of the attribute to be removed.\\
+  {\tt obj} & (IN): The container or object where the operation needs
+  to happen.\\
+  {\tt misc\_type} & (IN): The type of the operation.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
+  {\tt arguments} & (IN/OUT): argument list containing parameters and
+  output pointers for the get operation. \\
 \end{tabular}
 
-The {\tt close} callback in the attribute class should terminate
-access to the attribute object and free all resources it was
-consuming, and returns an {\tt herr\_t} indicating success or failure.
+The {\tt arguments} argument contains a variable list of arguments
+depending on the {\tt misc\_type} parameter. The following list shows
+the argument list, in-order, for each type:
+
+\begin{itemize}
+\item {\tt H5VL\_FILE\_MOUNT}, Mounts a file on the location object:
+  \begin{enumerate}
+  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
+  \item {\tt char *name} (IN): name of the group onto which the file
+    specified by {\tt file} is to be mounted.
+  \item {\tt void *file} (IN): child file to be mounted.
+  \item {\tt hid\_t *fmpl\_id} (IN): file mount property list.
+  \end{enumerate}
+
+\item {\tt H5VL\_FILE\_UNMOUNT}, un-mounts a file from the location object:
+  \begin{enumerate}
+  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
+  \item {\tt char *name} (IN): name of the mount point.
+  \end{enumerate}
+
+\item {\tt H5VL\_FILE\_IS\_ACCESSIBLE}, checks if a container is
+  accessible using a specific file access property list:
+  \begin{enumerate}
+  \item {\tt hid\_t *fapl\_id} (IN): file access property list.
+  \item {\tt char *name} (IN): name of the container to check.
+  \item {\tt htri\_t *result} (OUT): buffer for the result; 0 if no, 1
+    if yes.
+  \end{enumerate}
+\end{itemize}
+
+The {\tt optional} callback in the file class should execute some
+operations considered native HDF5 specific operations on the container
+as specified in the {\tt optional\_type} parameter. It returns an {\tt
+  herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*close)(void *attr, hid_t dxpl_id, void **req);
+    herr_t (*optional)(void *obj, H5VL_file_optional_t op_type, 
+        hid_t dxpl_id, void **req, va_list arguments);
+\end{lstlisting}
+
+The {\tt optional\_type} argument is an {\tt enum}:
+\begin{lstlisting}
+/* types for all file optional operations */
+typedef enum H5VL_file_optional_t {
+    H5VL_FILE_CLEAR_ELINK_CACHE,  /* Clear external link cache         */
+    H5VL_FILE_GET_FILE_IMAGE,     /* file image                        */
+    H5VL_FILE_GET_FREE_SECTIONS,  /* file free selections              */
+    H5VL_FILE_GET_FREE_SPACE,     /* file freespace                    */
+    H5VL_FILE_GET_INFO,           /* file info                         */
+    H5VL_FILE_GET_MDC_CONF,       /* file metadata cache configuration */
+    H5VL_FILE_GET_MDC_HR,         /* file metadata cache hit rate      */
+    H5VL_FILE_GET_MDC_SIZE,       /* file metadata cache size          */
+    H5VL_FILE_GET_SIZE,           /* file size                         */
+    H5VL_FILE_GET_VFD_HANDLE,     /* file VFD handle                   */
+    H5VL_FILE_REOPEN,             /* reopen the file                   */
+    H5VL_FILE_RESET_MDC_HIT_RATE, /* get metadata cache hit rate       */
+    H5VL_FILE_SET_MDC_CONFIG      /* set metadata cache configuration  */
+} H5VL_file_optional_t;
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt attr} & (IN): Pointer to the attribute object.\\
+  {\tt obj} & (IN): The container or object where the operation needs
+  to happen.\\
+  {\tt optional\_type} & (IN): The type of the operation.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
+  {\tt arguments} & (IN/OUT): argument list containing parameters and
+  output pointers for the get operation. \\
 \end{tabular}
 
-\subsection{The Named Datatype Function Callbacks}
-The HDF5 datatype routines (H5T) allow users to create and manage HDF5
-datatypes. Those routines are divided into two categories. One that
-operates on all types of datatypes but do not modify the contents of
-the container (all in memory), and others that operate on named
-datatypes by accessing the container. When a user creates an HDF5
-datatype, it is still an object in memory space (transient datatype)
-that has not been added to the HDF5 containers. Only when a user
-commits the HDF5 datatype, it becomes persistent in the
-container. Those are called named/committed datatypes. The transient
-H5T routines should work on named datatypes nevertheless. 
+The {\tt arguments} argument contains a variable list of arguments
+depending on the {\tt optional\_type} parameter. The following list
+shows the argument list, in-order, for each type:
 
-All the H5T API routines that modify the HDF5 container map to one of
-the named datatype callback routines in this class that the plugin needs to
-implement:
+\begin{itemize}
 
-\begin{lstlisting}
-typedef struct H5VL_datatype_class_t {
-    void *(*commit)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, 
-        hid_t tapl_id, hid_t dxpl_id, void **req);
+\item {\tt H5VL\_FILE\_GET\_SIZE}, retrieve the size of the container
+  in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt hsize\_t *ret} (OUT): file size.
+  \end{enumerate}
 
-    void *(*open) (void *obj, H5VL_loc_params_t loc_params, 
-        const char * name, hid_t tapl_id, hid_t dxpl_id, void **req);
+\item {\tt H5VL\_FILE\_GET\_FILE\_IMAGE}, retrieve file image from the
+  container in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt void *buf\_ptr} (OUT): buffer to return the file image.
+  \item {\tt ssize\_t *ret} (OUT): buffer for the total size needed for
+    the file image.
+  \item {\tt size\_t buf\_len} (IN): size of the buffer passed in.
+  \end{enumerate}
 
-    ssize_t (*get_binary)(void *obj, unsigned char *buf, size_t size, 
-        hid_t dxpl_id, void **req);
+\item {\tt H5VL\_FILE\_GET\_FREE\_SPACE}, retrieve amount of free
+  space in the container in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt hssize\_t *ret} (OUT): buffer for the free space.
+  \end{enumerate}
 
-    herr_t (*get) (void *obj, H5VL_datatype_get_t get_type, 
-        hid_t dxpl_id, void **req, va_list arguments);
+\item {\tt H5VL\_FILE\_GET\_FREE\_SECTIONS}, retrieve free sections from the
+  container in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt H5F\_sect\_info\_t *sinfo} (OUT): pointer to the section
+    info structure to fill.
+  \item {\tt ssize\_t *ret} (OUT): buffer for the total number of free
+    sections.
+  \item {\tt H5F\_mem\_t type} (IN): type of the memory space to check
+    for.
+  \item {\tt size\_t nsects} (IN): number of section allocate in {\tt sinfo}.
+  \end{enumerate}
 
-    herr_t (*close) (void *dt, hid_t dxpl_id, void **req);
-} H5VL_datatype_class_t;
-\end{lstlisting}
+\item {\tt H5VL\_FILE\_GET\_INFO}, retrieve file info from the
+  object in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
+  \item {\tt H5F\_info2\_t *finfo} (OUT): pointer to info structure to fill.
+  \end{enumerate}
 
-The {\tt commit} callback in the named datatype class should create a datatype object in the container of the location object and
-returns a pointer to the datatype structure containing information to
-access the datatype in future calls. 
+\item {\tt H5VL\_FILE\_GET\_MDC\_CONF}, retrieve the meta data cache
+  configuration from the container in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
+  \item {\tt H5AC\_cache\_config\_t *conf} (OUT): pointer to
+    configuration structure to fill.
+  \end{enumerate}
+
+\item {\tt H5VL\_FILE\_GET\_MDC\_HR}, retrieve the meta data cache
+  hit rate from the container in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt double *ret} (OUT): buffer for the hit rate.
+  \end{enumerate}
+
+\item {\tt H5VL\_FILE\_GET\_MDC\_SIZE}, retrieve the meta data cache
+  size information from the container in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt size\_t max\_size\_ptr} (OUT): buffer for maximum size.
+  \item {\tt size\_t min\_clean\_size\_ptr} (OUT): buffer for minimum
+    clean size.
+  \item {\tt size\_t cur\_size\_ptr} (OUT): buffer for current size.
+  \item {\tt int cur\_num\_entries\_ptr} (OUT): buffer for number of
+    current cache entries.
+  \end{enumerate}
+
+\item {\tt H5VL\_FILE\_GET\_VFD\_HANDLE}, retrieve the virtual file
+  driver handle from the container in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt void **handle} (OUT): pointer to a buffer the plugin sets
+    to the VFD handle.
+  \item {\tt hid\_t fapl} (IN): File access property list.
+  \end{enumerate}
+
+\item {\tt H5VL\_FILE\_CLEAR\_ELINK\_CACHE}, clears the external link
+  file cache. Takes no extra arguments.
+
+\item {\tt H5VL\_FILE\_REOPEN}, reopen the container in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt void **ret} (OUT): pointer to be set to the opened file
+    structure.
+  \end{enumerate}
+
+\item {\tt H5VL\_FILE\_RESET\_MDC\_HIT\_RATE}, resets the hit rate
+  statistics for the metadata cache on the container in {\tt
+    obj}. Takes no extra arguments.
+
+\item {\tt H5VL\_FILE\_SET\_MDC\_CONFIG}, sets the meta data cache
+  configuration for the container in {\tt obj}:
+  \begin{enumerate}
+  \item {\tt H5AC\_cache\_config\_t *conf} (IN): pointer to
+    configuration structure to use.
+  \end{enumerate}
+
+\end{itemize}
+
+The {\tt close} callback in the file class should terminate access to
+the file object and free all resources it was consuming, and returns
+an {\tt herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    void *(*commit)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, 
-        hid_t tapl_id, hid_t dxpl_id, void **req);
+    herr_t (*close)(void *file, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to an object where the datatype needs
-  to be committed or where the look-up of the target object needs to
-  start.\\
-  {\tt loc\_params} & (IN): The location parameters as explained in
-  section~\ref{sec:map}. In this call, the location type is always {\tt
-    H5VL\_OBJECT\_BY\_SELF}. \\
-  {\tt name} & (IN): The name of the datatype to be created.\\
-  {\tt type\_id} & (IN): The transient datatype identifier to be
-  committed. \\
-  {\tt lcpl\_id} & (IN): The link creation property list. \\
-  {\tt tcpl\_id} & (IN): The datatype creation property list.\\
-  {\tt tapl\_id} & (IN): The datatype access property list.\\
+  {\tt file} & (IN): Pointer to the file.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt open} callback in the named datatype class should open a
-previously committed datatype object in the container of the location
-object and returns a pointer to the datatype structure containing
-information to access the datatype in future calls.
+\subsection{The Group Function Callbacks}
+The group API routines (H5G) allow HDF5 users to create and manage
+HDF5 groups. All the H5G API routines that modify the HDF5 container
+map to one of the group callback routines in this class that the
+plugin needs to implement:
+
+\begin{lstlisting}
+typedef struct H5VL_group_class_t {
+    void *(*create)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, 
+        void **req);
+
+    void *(*open)(void *obj, H5VL_loc_params_t loc_params, 
+        const char*name, hid_t gapl_id, hid_t dxpl_id, void **req);
+
+    herr_t (*get)(void *obj, H5VL_group_get_t get_type, hid_t dxpl_id, 
+        void **req, va_list arguments);
+
+    herr_t (*close) (void *grp, hid_t dxpl_id, void **req);
+} H5VL_group_class_t;
+\end{lstlisting}
+
+The {\tt create} callback in the group class should create a group
+object in the container of the location object and returns a pointer
+to the group structure containing information to access the group in
+future calls.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    void *(*open) (void *obj, H5VL_loc_params_t loc_params, 
-        const char * name, hid_t tapl_id, hid_t dxpl_id, void **req);
+    void *(*create)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, 
+        void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to an object where the datatype needs
-  to be opened or where the look-up of the target object needs to
+  {\tt obj} & (IN): Pointer to an object where the group needs
+  to be created or where the look-up of the target object needs to
   start.\\
   {\tt loc\_params} & (IN): The location parameters as explained in
-  section~\ref{sec:map}. In this call, the location type is always {\tt
-    H5VL\_OBJECT\_BY\_SELF}. \\
-  {\tt name} & (IN): The name of the datatype to be opened.\\
-  {\tt tapl\_id} & (IN): The datatype access property list.\\
+  section~\ref{sec:map}. The type can be only {\tt
+    H5VL\_OBJECT\_BY\_SELF} in this callback. \\
+  {\tt name} & (IN): The name of the group to be created.\\
+  {\tt dcpl\_id} & (IN): The group creation property list. It contains
+  all the group creation properties in addition to the link creation
+  property list of the create operation (an {\tt hid\_t}) that can be
+  retrieved with the property {\tt H5VL\_GRP\_LCPL\_ID}.\\
+  {\tt gapl\_id} & (IN): The group access property list.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt get\_binary} callback in the named datatype class should
-serialize the original transient HDF5 datatype that was committed, or
-return the size that is required for it be serialized if the passed in
-buffer is {\tt NULL}. The HDF5 library provides two functions to
-encode and decode datatypes in their transient form, {\tt H5Tencode()}
-and {\tt H5Tdecode()}. When a datatype is committed, the plugin is
-required to keep the serialized form of the transient datatype stored
-somewhere in the container (which is usually the case anyway when
-committing a named datatype), so it can be retrieved with this
-call. This is needed to generate the higher level HDF5 datatype
-identifier that allows all the H5T ``transient'' routines to work
-properly on the named datatype.
+The {\tt open} callback in the group class should open a group object
+in the container of the location object and returns a pointer to the
+group structure containing information to access the group in future
+calls.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    ssize_t (*get_binary)(void *obj, unsigned char *buf, size_t size, 
-        hid_t dxpl_id, void **req);
+    void *(*open)(void *obj, H5VL_loc_params_t loc_params, 
+        const char*name, hid_t gapl_id, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to the named datatype object.\\
-  {\tt buf} & (OUT): Buffer to out the binary form of the datatype in.\\
-  {\tt size} & (IN): The size of the buffer passed in (0 if NULL).\\
+  {\tt obj} & (IN): Pointer to an object where the group needs to be
+  opened or where the look-up of the target object needs to start.\\
+  {\tt loc\_params} & (IN): The location parameters as explained in
+  section~\ref{sec:map}. The type can be only {\tt
+    H5VL\_OBJECT\_BY\_SELF} in this callback. \\
+  {\tt name} & (IN): The name of the group to be opened.\\
+  {\tt dapl\_id} & (IN): The group access property list.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt get} callback in the named datatype class should retrieve
-information about the named datatype as specified in the {\tt get\_type}
-parameter.It returns an {\tt herr\_t} indicating success or failure.
+The {\tt get} callback in the group class should retrieve information
+about the group as specified in the {\tt get\_type} parameter. It
+returns an {\tt herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*get) (void *obj, H5VL_datatype_get_t get_type, 
-        hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*get)(void *obj, H5VL_group_get_t get_type, hid_t dxpl_id, 
+        void **req, va_list arguments);
 \end{lstlisting}
 
 The {\tt get\_type} argument is an {\tt enum}:
 \begin{lstlisting}
-/* types for all datatype get API routines */
-typedef enum H5VL_datatype_get_t {
-    H5VL_DATATYPE_GET_TCPL   /*datatype creation property list */
-} H5VL_datatype_get_t;
+/* types for all group get API routines */
+typedef enum H5VL_group_get_t {
+    H5VL_GROUP_GET_GCPL,      /*group creation property list */
+    H5VL_GROUP_GET_INFO       /*group info                   */
+} H5VL_group_get_t;
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): The named datatype to retrieve information from.\\
+  {\tt obj} & (IN): The group object where information needs to be
+  retrieved from.\\
   {\tt get\_type} & (IN): The type of the information to retrieve.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
@@ -651,33 +720,40 @@ depending on the {\tt get\_type} parameter. The following list shows
 the argument list, in-order, for each type:
 
 \begin{itemize}
-\item {\tt H5VL\_DATATYPE\_GET\_TCPL}, to retrieve the datatype
-  creation property list:
+\item {\tt H5VL\_GROUP\_GET\_GCPL}, to retrieve the group creation
+  property list of the group specified in {\tt obj}:
   \begin{enumerate}
   \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
-    type creation property list.
+    group creation property list.
+  \end{enumerate}
+
+\item {\tt H5VL\_GROUP\_GET\_INFO}, to retrieve the attribute info:
+  \begin{enumerate}
+  \item {\tt H5VL\_loc\_params\_t loc\_params} (IN): The location parameters
+    explained in section~\ref{sec:map}. 
+  \item {\tt H5G\_info\_t *ginfo} (OUT): info structure to fill the
+    group info in.
   \end{enumerate}
 \end{itemize}
 
-The {\tt close} callback in the named datatype class should terminate
-access to the datatype object and free all resources it was
-consuming, and returns an {\tt herr\_t} indicating success or failure.
+The {\tt close} callback in the group class should terminate access to
+the group object and free all resources it was consuming, and returns
+an {\tt herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*close) (void *dt, hid_t dxpl_id, void **req);
+    herr_t (*close)(void *group, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt dt} & (IN): Pointer to the datatype object.\\
+  {\tt group} & (IN): Pointer to the group object.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
 \subsection{The Dataset Function Callbacks}
-
 The dataset API routines (H5D) allow HDF5 users to create and manage
 HDF5 datasets. All the H5D API routines that modify the HDF5 container
 map to one of the dataset callback routines in this class that the
@@ -938,295 +1014,196 @@ returns an {\tt herr\_t} indicating success or failure.
   operation created by the plugin.\\
 \end{tabular}
 
-\subsection{The File Function Callbacks}
-The file API routines (H5F) allow HDF5 users to create and manage HDF5
-containers. All the H5F API routines that modify the HDF5 container
-map to one of the file callback routines in this class that the plugin
-needs to implement:
+\subsection{The Attribute Function Callbacks}
+The attribute API routines (H5A) allow HDF5 users to create and manage
+HDF5 attributes. All the H5A API routines that modify the HDF5
+container map to one of the attribute callback routines in this
+class that the plugin needs to implement:
 
 \begin{lstlisting}
-typedef struct H5VL_file_class_t {
-    void *(*create)(const char *name, unsigned flags, hid_t fcpl_id,
-        hid_t fapl_id, hid_t dxpl_id, void **req);
+typedef struct H5VL_attr_class_t {
+    void *(*create)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *attr_name, hid_t acpl_id, hid_t aapl_id, 
+        hid_t dxpl_id, void **req);
 
-    void *(*open)(const char *name, unsigned flags, hid_t fapl_id, 
+    void *(*open)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *attr_name, hid_t aapl_id, hid_t dxpl_id, void **req);
+
+    herr_t (*read)(void *attr, hid_t mem_type_id, void *buf, 
         hid_t dxpl_id, void **req);
 
-    herr_t (*flush)(void *obj, H5VL_loc_params_t loc_params, 
-        H5F_scope_t scope, hid_t dxpl_id, void **req);
+    herr_t (*write)(void *attr, hid_t mem_type_id, const void *buf, 
+        hid_t dxpl_id, void **req);
 
-    herr_t (*get)(void *obj, H5VL_file_get_t get_type, hid_t dxpl_id, 
-        void **req, va_list arguments);
+    herr_t (*iterate)(void *obj, H5VL_loc_params_t loc_params,
+        H5_index_t idx_type, H5_iter_order_t order, hsize_t *n, 
+        H5A_operator2_t  op, void *op_data, hid_t dxpl_id, void **req);
 
-    herr_t (*misc)(void *obj, H5VL_file_misc_t misc_type, 
-        hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*get)(void *obj, H5VL_attr_get_t get_type, hid_t dxpl_id, 
+        void **req, va_list arguments);
 
-    herr_t (*optional)(void *obj, H5VL_file_optional_t op_type, 
-        hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *attr_name, hid_t dxpl_id, void **req);
 
-    herr_t (*close) (void *file, hid_t dxpl_id, void **req);
-} H5VL_file_class_t;
+    herr_t (*close)(void *attr, hid_t dxpl_id, void **req);
+} H5VL_attr_class_t;
 \end{lstlisting}
 
-The {\tt create} callback in the file class should create a container
-and returns a pointer to the file structure containing information to
-access the container in future calls.
+The {\tt create} callback in the attribute class should create an
+attribute object in the container of the location object and
+returns a pointer to the attribute structure containing information to
+access the attribute in future calls. 
 
 \textbf{Signature:}
 \begin{lstlisting}
-    void *(*create)(const char *name, unsigned flags, hid_t fcpl_id,
-        hid_t fapl_id, hid_t dxpl_id, void **req);
+    void *(*create)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *attr_name, hid_t acpl_id, hid_t aapl_id, 
+        hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt name} & (IN): The name of the container to be created.\\
-  {\tt flags} & (IN): The creation flags of the container.\\
-  {\tt fcpl\_id} & (IN): The file creation property list.\\
-  {\tt fapl\_id} & (IN): The file access property list.\\
+  {\tt obj} & (IN): Pointer to an object where the attribute needs
+  to be created or where the look-up of the target object needs to
+  start.\\
+  {\tt loc\_params} & (IN): The location parameters as explained in
+  section~\ref{sec:map}.\\
+  {\tt attr\_name} & (IN): The name of the attribute to be created.\\
+  {\tt acpl\_id} & (IN): The attribute creation property list. It contains
+  all the attribute creation properties in addition to the attribute
+  datatype (an {\tt hid\_t}) and dataspace (an {\tt hid\_t}) that can
+  be retrieved with the properties, {\tt H5VL\_ATTR\_TYPE\_ID} and
+  {\tt H5VL\_ATTR\_SPACE\_ID}.\\
+  {\tt aapl\_id} & (IN): The attribute access property list.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt open} callback in the file class should open a container and
-returns a pointer to the file structure containing information to
-access the container in future calls.
+The {\tt open} callback in the attribute class should open an
+attribute object in the container of the location object and returns a
+pointer to the attribute structure containing information to access
+the attribute in future calls. 
 
 \textbf{Signature:}
 \begin{lstlisting}
-    void *(*open)(const char *name, unsigned flags, hid_t fapl_id, 
-        hid_t dxpl_id, void **req);
+    void *(*open)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *attr_name, hid_t aapl_id, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt name} & (IN): The name of the container to open.\\
-  {\tt flags} & (IN): The open flags of the container.\\
-  {\tt fapl\_id} & (IN): The file access property list.\\
+  {\tt obj} & (IN): Pointer to an object where the attribute needs to be
+  opened or where the look-up of the target object needs to start.\\
+  {\tt loc\_params} & (IN): The location parameters as explained in
+  section~\ref{sec:map}.\\
+  {\tt attr\_name} & (IN): The name of the attribute to be opened.\\
+  {\tt aapl\_id} & (IN): The attribute access property list.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt flush} callback in the file class should flush all buffers
-associated with the container to disk and returns an {\tt herr\_t}
-indicating success or failure.
+The {\tt read} callback in the attribute class should read data from
+the attribute object and returns an {\tt herr\_t} indicating success or
+failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*flush)(void *obj, H5VL_loc_params_t loc_params, 
-        H5F_scope_t scope, hid_t dxpl_id, void **req);
+    herr_t (*read)(void *attr, hid_t mem_type_id, void *buf, 
+        hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to a file or object in the file to be flushed.\\
-  {\tt loc\_params} & (IN): The location parameters as explained in
-  section~\ref{sec:map}. The type can be only {\tt
-    H5VL\_OBJECT\_BY\_SELF} in this callback. \\
-  {\tt scope} & (IN): The scope of the flushing action.\\
+  {\tt attr} & (IN): Pointer to the attribute object.\\
+  {\tt mem\_type\_id} & (IN): The memory datatype of the attribute.\\
+  {\tt buf} & (OUT): Data buffer to be read into.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt get} callback in the file class should retrieve
-information about the container as specified in the {\tt get\_type}
-parameter.It returns an {\tt herr\_t} indicating success or failure.
+The {\tt write} callback in the attribute class should write data to
+the attribute object and returns an {\tt herr\_t} indicating success or
+failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*get)(void *obj, H5VL_file_get_t get_type, hid_t dxpl_id, 
-        void **req, va_list arguments);
-\end{lstlisting}
-
-The {\tt get\_type} argument is an {\tt enum}:
-\begin{lstlisting}
-/* types for all file get API routines */
-typedef enum H5VL_file_get_t {
-    H5VL_FILE_GET_FAPL,      /* file access property list   */
-    H5VL_FILE_GET_FCPL,      /* file creation property list */
-    H5VL_FILE_GET_INTENT,    /* file intent                 */
-    H5VL_FILE_GET_NAME,      /* file name                   */
-    H5VL_FILE_GET_OBJ_COUNT, /* object count in file        */
-    H5VL_FILE_GET_OBJ_IDS,   /* object ids in file          */
-    H5VL_OBJECT_GET_FILE
-} H5VL_file_get_t;
+    herr_t (*write)(void *attr, hid_t mem_type_id, const void *buf, 
+        hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): The container or object where information needs to be
-  retrieved from.\\
-  {\tt get\_type} & (IN): The type of the information to retrieve.\\
+  {\tt attr} & (IN): Pointer to the attribute object.\\
+  {\tt mem\_type\_id} & (IN): The memory datatype of the attribute.\\
+  {\tt buf} & (IN): Data buffer to be written.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
-  {\tt arguments} & (IN/OUT): argument list containing parameters and
-  output pointers for the get operation. \\
 \end{tabular}
 
-The {\tt arguments} argument contains a variable list of arguments
-depending on the {\tt get\_type} parameter. The following list shows
-the argument list, in-order, for each type:
-
-\begin{itemize}
-\item {\tt H5VL\_FILE\_GET\_FCPL}, to retrieve the file creation
-  property list:
-  \begin{enumerate}
-  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
-    file creation property list.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_GET\_FAPL}, to retrieve the file access
-  property list:
-  \begin{enumerate}
-  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
-    file access property list.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_GET\_OBJ\_COUNT:}, to retrieve the object count
-  in the container:
-  \begin{enumerate}
-  \item {\tt unsigned types} (IN): type of objects to look for.
-  \item {\tt ssize\_t *ret} (OUT): buffer for the object count.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_GET\_OBJ\_IDS:}, to retrieve object identifiers
-  in the container:
-  \begin{enumerate}
-  \item {\tt unsigned types} (IN): type of objects to look for.
-  \item {\tt size\_t max\_objs} (IN): maximum number of objects to
-    open.
-  \item {\tt hid\_t *oid\_list} (OUT): buffer for the object identifiers.
-  \item {\tt ssize\_t *ret} (OUT): buffer for the object count.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_GET\_INTENT}, get access intent of the
-  container:
-  \begin{enumerate}
-  \item {\tt unsigned *ret} (OUT): buffer for the intent value.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_GET\_NAME}, get container name an object
-  belongs to:
-  \begin{enumerate}
-  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
-  \item {\tt size\_t size} (IN): size of the buffer for the file name.
-  \item {\tt char *name} (OUT): buffer for the file name.
-  \item {\tt ssize\_t *ret} (OUT): buffer for the entire size of the
-    file name.
-  \end{enumerate}
-
-\item {\tt H5VL\_OBJECT\_GET\_FILE}, get the container that the object
-  belongs to:
-  \begin{enumerate}
-  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
-  \item {\tt void **ret} (OUT): pointer to the file structure returned
-    by the plugin.
-  \end{enumerate}
-\end{itemize}
-
-The {\tt misc} callback in the file class should execute some not very
-common operations on the container as specified in the {\tt
-  misc\_type} parameter. It returns an {\tt herr\_t} indicating
-success or failure.
+The {\tt iterate} callback in the attribute class should iterate over
+the attributes in the container of the location object and call the
+user defined function on each one. It returns an {\tt herr\_t}
+indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*misc)(void *obj, H5VL_file_misc_t misc_type, hid_t dxpl_id, 
-        void **req, va_list arguments);
-\end{lstlisting}
-
-The {\tt misc\_type} argument is an {\tt enum}:
-\begin{lstlisting}
-/* types for all file misc operations */
-typedef enum H5VL_file_misc_t {
-    H5VL_FILE_MOUNT,         /* H5Fmount                     */
-    H5VL_FILE_UNMOUNT,       /* H5Funmount                   */
-    H5VL_FILE_IS_ACCESSIBLE  /* is the container accessible? */
-} H5VL_file_misc_t;
+    herr_t (*iterate)(void *obj, H5VL_loc_params_t loc_params,
+        H5_index_t idx_type, H5_iter_order_t order, hsize_t *n, 
+        H5A_operator2_t  op, void *op_data, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): The container or object where the operation needs
-  to happen.\\
-  {\tt misc\_type} & (IN): The type of the operation.\\
+  {\tt obj} & (IN): Pointer to an object where the iteration needs
+  to happen or where the look-up of the target object needs to
+  start.\\
+  {\tt loc\_params} & (IN): The location parameters as
+  explained in section~\ref{sec:map}.\\
+  {\tt idx\_type} & (IN): Type of index.\\
+  {\tt order} & (IN): Order in which to iterate over index.\\
+  {\tt n} & (IN/OUT): Initial and return offset withing index.\\
+  {\tt op} & (IN): User-defined function to pass each
+  attribute to. \\
+  {\tt op\_data} & (IN/OUT): User data to pass through to and to be
+  returned by iterator operator function. \\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
-  {\tt arguments} & (IN/OUT): argument list containing parameters and
-  output pointers for the get operation. \\
 \end{tabular}
 
-The {\tt arguments} argument contains a variable list of arguments
-depending on the {\tt misc\_type} parameter. The following list shows
-the argument list, in-order, for each type:
-
-\begin{itemize}
-\item {\tt H5VL\_FILE\_MOUNT}, Mounts a file on the location object:
-  \begin{enumerate}
-  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
-  \item {\tt char *name} (IN): name of the group onto which the file
-    specified by {\tt file} is to be mounted.
-  \item {\tt void *file} (IN): child file to be mounted.
-  \item {\tt hid\_t *fmpl\_id} (IN): file mount property list.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_UNMOUNT}, un-mounts a file from the location object:
-  \begin{enumerate}
-  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
-  \item {\tt char *name} (IN): name of the mount point.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_IS\_ACCESSIBLE}, checks if a container is
-  accessible using a specific file access property list:
-  \begin{enumerate}
-  \item {\tt hid\_t *fapl\_id} (IN): file access property list.
-  \item {\tt char *name} (IN): name of the container to check.
-  \item {\tt htri\_t *result} (OUT): buffer for the result; 0 if no, 1
-    if yes.
-  \end{enumerate}
-\end{itemize}
-
-The {\tt optional} callback in the file class should execute some
-operations considered native HDF5 specific operations on the container
-as specified in the {\tt optional\_type} parameter. It returns an {\tt
-  herr\_t} indicating success or failure.
+The {\tt get} callback in the attribute class should retrieve
+information about the attribute as specified in the {\tt get\_type}
+parameter.It returns an {\tt herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*optional)(void *obj, H5VL_file_optional_t op_type, 
-        hid_t dxpl_id, void **req, va_list arguments);
+    herr_t (*get)(void *obj, H5VL_attr_get_t get_type, hid_t dxpl_id, 
+        void **req, va_list arguments);
 \end{lstlisting}
 
-The {\tt optional\_type} argument is an {\tt enum}:
+The {\tt get\_type} argument is an {\tt enum}:
 \begin{lstlisting}
-/* types for all file optional operations */
-typedef enum H5VL_file_optional_t {
-    H5VL_FILE_CLEAR_ELINK_CACHE,  /* Clear external link cache         */
-    H5VL_FILE_GET_FILE_IMAGE,     /* file image                        */
-    H5VL_FILE_GET_FREE_SECTIONS,  /* file free selections              */
-    H5VL_FILE_GET_FREE_SPACE,     /* file freespace                    */
-    H5VL_FILE_GET_INFO,           /* file info                         */
-    H5VL_FILE_GET_MDC_CONF,       /* file metadata cache configuration */
-    H5VL_FILE_GET_MDC_HR,         /* file metadata cache hit rate      */
-    H5VL_FILE_GET_MDC_SIZE,       /* file metadata cache size          */
-    H5VL_FILE_GET_SIZE,           /* file size                         */
-    H5VL_FILE_GET_VFD_HANDLE,     /* file VFD handle                   */
-    H5VL_FILE_REOPEN,             /* reopen the file                   */
-    H5VL_FILE_RESET_MDC_HIT_RATE, /* get metadata cache hit rate       */
-    H5VL_FILE_SET_MDC_CONFIG      /* set metadata cache configuration  */
-} H5VL_file_optional_t;
+/* types for all attr get API routines */
+typedef enum H5VL_attr_get_t {
+    H5VL_ATTR_EXISTS,           /* attribute exists?       */
+    H5VL_ATTR_GET_SPACE,        /* dataspace               */
+    H5VL_ATTR_GET_TYPE,         /* datatype                */
+    H5VL_ATTR_GET_ACPL,         /* creation property list  */
+    H5VL_ATTR_GET_NAME,         /* access property list    */
+    H5VL_ATTR_GET_STORAGE_SIZE, /* storage size            */
+    H5VL_ATTR_GET_INFO          /* offset                  */
+} H5VL_attr_get_t;
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): The container or object where the operation needs
-  to happen.\\
-  {\tt optional\_type} & (IN): The type of the operation.\\
+  {\tt attr} & (IN): An attribute or location object where information
+  needs to be retrieved from.\\
+  {\tt get\_type} & (IN): The type of the information to retrieve.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
@@ -1235,467 +1212,254 @@ typedef enum H5VL_file_optional_t {
 \end{tabular}
 
 The {\tt arguments} argument contains a variable list of arguments
-depending on the {\tt optional\_type} parameter. The following list
-shows the argument list, in-order, for each type:
+depending on the {\tt get\_type} parameter. The following list shows
+the argument list, in-order, for each type:
 
 \begin{itemize}
-
-\item {\tt H5VL\_FILE\_GET\_SIZE}, retrieve the size of the container
-  in {\tt obj}:
-  \begin{enumerate}
-  \item {\tt hsize\_t *ret} (OUT): file size.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_GET\_FILE\_IMAGE}, retrieve file image from the
-  container in {\tt obj}:
-  \begin{enumerate}
-  \item {\tt void *buf\_ptr} (OUT): buffer to return the file image.
-  \item {\tt ssize\_t *ret} (OUT): buffer for the total size needed for
-    the file image.
-  \item {\tt size\_t buf\_len} (IN): size of the buffer passed in.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_GET\_FREE\_SPACE}, retrieve amount of free
-  space in the container in {\tt obj}:
-  \begin{enumerate}
-  \item {\tt hssize\_t *ret} (OUT): buffer for the free space.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_GET\_FREE\_SECTIONS}, retrieve free sections from the
-  container in {\tt obj}:
-  \begin{enumerate}
-  \item {\tt H5F\_sect\_info\_t *sinfo} (OUT): pointer to the section
-    info structure to fill.
-  \item {\tt ssize\_t *ret} (OUT): buffer for the total number of free
-    sections.
-  \item {\tt H5F\_mem\_t type} (IN): type of the memory space to check
-    for.
-  \item {\tt size\_t nsects} (IN): number of section allocate in {\tt sinfo}.
-  \end{enumerate}
-
-\item {\tt H5VL\_FILE\_GET\_INFO}, retrieve file info from the
-  object in {\tt obj}:
+\item {\tt H5VL\_ATTR\_EXISTS}, to check if an attribute exists on a
+  particular object specified in {\tt obj}:
   \begin{enumerate}
-  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
-  \item {\tt H5F\_info2\_t *finfo} (OUT): pointer to info structure to fill.
+  \item {\tt H5VL\_loc\_params\_t loc\_params} (IN): The location parameters
+    explained in section~\ref{sec:map}.
+  \item {\tt char *attr\_name} (IN): the attribute name to check.
+  \item {\tt htri\_t *ret} (OUT): existence result, 0 if false, 1 if true.
   \end{enumerate}
 
-\item {\tt H5VL\_FILE\_GET\_MDC\_CONF}, retrieve the meta data cache
-  configuration from the container in {\tt obj}:
+\item {\tt H5VL\_ATTR\_GET\_SPACE}, to retrieve the dataspace of the
+  attribute specified in {\tt obj}:
   \begin{enumerate}
-  \item {\tt H5I\_type\_t type} (IN): the object type in {\tt obj}.
-  \item {\tt H5AC\_cache\_config\_t *conf} (OUT): pointer to
-    configuration structure to fill.
+  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
+    attribute dataspace.
   \end{enumerate}
 
-\item {\tt H5VL\_FILE\_GET\_MDC\_HR}, retrieve the meta data cache
-  hit rate from the container in {\tt obj}:
+\item {\tt H5VL\_ATTR\_GET\_TYPE}, to retrieve the datatype of the
+  attribute specified in {\tt obj}:
   \begin{enumerate}
-  \item {\tt double *ret} (OUT): buffer for the hit rate.
+  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
+    attribute datatype.
   \end{enumerate}
 
-\item {\tt H5VL\_FILE\_GET\_MDC\_SIZE}, retrieve the meta data cache
-  size information from the container in {\tt obj}:
+\item {\tt H5VL\_ATTR\_GET\_ACPL}, to retrieve the attribute creation
+  property list of the attribute specified in {\tt obj}:
   \begin{enumerate}
-  \item {\tt size\_t max\_size\_ptr} (OUT): buffer for maximum size.
-  \item {\tt size\_t min\_clean\_size\_ptr} (OUT): buffer for minimum
-    clean size.
-  \item {\tt size\_t cur\_size\_ptr} (OUT): buffer for current size.
-  \item {\tt int cur\_num\_entries\_ptr} (OUT): buffer for number of
-    current cache entries.
+  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
+    attribute creation property list.
   \end{enumerate}
 
-\item {\tt H5VL\_FILE\_GET\_VFD\_HANDLE}, retrieve the virtual file
-  driver handle from the container in {\tt obj}:
+\item {\tt H5VL\_ATTR\_GET\_NAME}, to retrieve an attribute name on a
+  particular object specified in {\tt obj}:
   \begin{enumerate}
-  \item {\tt void **handle} (OUT): pointer to a buffer the plugin sets
-    to the VFD handle.
-  \item {\tt hid\_t fapl} (IN): File access property list.
+  \item {\tt H5VL\_loc\_params\_t loc\_params} (IN): The location parameters
+    explained in section~\ref{sec:map}. The type could be either
+    {\tt H5VL\_OBJECT\_BY\_SELF} meaning {\tt obj} is the attribute,
+    or {\tt H5VL\_OBJECT\_BY\_IDX} meaning the attribute to retrieve
+    the name for should be looked up using the index information on
+    the object in {\tt obj} and the index information in {\tt loc\_params}.
+  \item {\tt size\_t buf\_size} (IN): the size of the buffer to store
+    the name in.
+  \item {\tt void *buf} (OUT): Buffer to store the name in.
+  \item {\tt ssize\_t *ret\_val} (OUT): return the actual size needed
+    to store the fill attribute name.
   \end{enumerate}
 
-\item {\tt H5VL\_FILE\_CLEAR\_ELINK\_CACHE}, clears the external link
-  file cache. Takes no extra arguments.
-
-\item {\tt H5VL\_FILE\_REOPEN}, reopen the container in {\tt obj}:
+\item {\tt H5VL\_ATTR\_GET\_INFO}, to retrieve the attribute info:
   \begin{enumerate}
-  \item {\tt void **ret} (OUT): pointer to be set to the opened file
-    structure.
+  \item {\tt H5VL\_loc\_params\_t loc\_params} (IN): The location parameters
+    explained in section~\ref{sec:map}. 
+  \item {\tt H5A\_info\_t *ainfo} (OUT): info structure to fill the
+    attribute info in.
   \end{enumerate}
 
-\item {\tt H5VL\_FILE\_RESET\_MDC\_HIT\_RATE}, resets the hit rate
-  statistics for the metadata cache on the container in {\tt
-    obj}. Takes no extra arguments.
-
-\item {\tt H5VL\_FILE\_SET\_MDC\_CONFIG}, sets the meta data cache
-  configuration for the container in {\tt obj}:
+\item {\tt H5VL\_ATTR\_GET\_STORAGE\_SIZE}, to retrieve the storage
+  size of the attribute specified in {\tt obj}:
   \begin{enumerate}
-  \item {\tt H5AC\_cache\_config\_t *conf} (IN): pointer to
-    configuration structure to use.
+  \item {\tt hsize\_t *ret} (OUT): buffer for the storage size of
+    the attribute in the container.
   \end{enumerate}
 
 \end{itemize}
 
-The {\tt close} callback in the file class should terminate access to
-the file object and free all resources it was consuming, and returns
+The {\tt remove} callback in the attribute class should remove an
+attribute object in the container of the location object and returns
 an {\tt herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*close)(void *file, hid_t dxpl_id, void **req);
-\end{lstlisting}
-
-\textbf{Arguments:}\\
-\begin{tabular}{l p{10cm}}
-  {\tt file} & (IN): Pointer to the file.\\
-  {\tt dxpl\_id} & (IN): The data transfer property list.\\
-  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
-  operation created by the plugin.\\
-\end{tabular}
-
-\subsection{The Group Function Callbacks}
-
-The group API routines (H5G) allow HDF5 users to create and manage
-HDF5 groups. All the H5G API routines that modify the HDF5 container
-map to one of the group callback routines in this class that the
-plugin needs to implement:
-
-\begin{lstlisting}
-typedef struct H5VL_group_class_t {
-    void *(*create)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, 
-        void **req);
-
-    void *(*open)(void *obj, H5VL_loc_params_t loc_params, 
-        const char*name, hid_t gapl_id, hid_t dxpl_id, void **req);
-
-    herr_t (*get)(void *obj, H5VL_group_get_t get_type, hid_t dxpl_id, 
-        void **req, va_list arguments);
-
-    herr_t (*close) (void *grp, hid_t dxpl_id, void **req);
-} H5VL_group_class_t;
-\end{lstlisting}
-
-The {\tt create} callback in the group class should create a group
-object in the container of the location object and returns a pointer
-to the group structure containing information to access the group in
-future calls.
-
-\textbf{Signature:}
-\begin{lstlisting}
-    void *(*create)(void *obj, H5VL_loc_params_t loc_params, 
-        const char *name, hid_t gcpl_id, hid_t gapl_id, hid_t dxpl_id, 
-        void **req);
+    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *attr_name, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to an object where the group needs
-  to be created or where the look-up of the target object needs to
+  {\tt obj} & (IN): Pointer to an object where the attribute needs
+  to be removed or where the look-up of the target object needs to
   start.\\
   {\tt loc\_params} & (IN): The location parameters as explained in
-  section~\ref{sec:map}. The type can be only {\tt
-    H5VL\_OBJECT\_BY\_SELF} in this callback. \\
-  {\tt name} & (IN): The name of the group to be created.\\
-  {\tt dcpl\_id} & (IN): The group creation property list. It contains
-  all the group creation properties in addition to the link creation
-  property list of the create operation (an {\tt hid\_t}) that can be
-  retrieved with the property {\tt H5VL\_GRP\_LCPL\_ID}.\\
-  {\tt gapl\_id} & (IN): The group access property list.\\
-  {\tt dxpl\_id} & (IN): The data transfer property list.\\
-  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
-  operation created by the plugin.\\
-\end{tabular}
-
-The {\tt open} callback in the group class should open a group object
-in the container of the location object and returns a pointer to the
-group structure containing information to access the group in future
-calls.
-
-\textbf{Signature:}
-\begin{lstlisting}
-    void *(*open)(void *obj, H5VL_loc_params_t loc_params, 
-        const char*name, hid_t gapl_id, hid_t dxpl_id, void **req);
-\end{lstlisting}
-
-\textbf{Arguments:}\\
-\begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): Pointer to an object where the group needs to be
-  opened or where the look-up of the target object needs to start.\\
-  {\tt loc\_params} & (IN): The location parameters as explained in
-  section~\ref{sec:map}. The type can be only {\tt
-    H5VL\_OBJECT\_BY\_SELF} in this callback. \\
-  {\tt name} & (IN): The name of the group to be opened.\\
-  {\tt dapl\_id} & (IN): The group access property list.\\
+  section~\ref{sec:map}.\\
+  {\tt attr\_name} & (IN): The name of the attribute to be removed.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt get} callback in the group class should retrieve information
-about the group as specified in the {\tt get\_type} parameter. It
-returns an {\tt herr\_t} indicating success or failure.
+The {\tt close} callback in the attribute class should terminate
+access to the attribute object and free all resources it was
+consuming, and returns an {\tt herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*get)(void *obj, H5VL_group_get_t get_type, hid_t dxpl_id, 
-        void **req, va_list arguments);
-\end{lstlisting}
-
-The {\tt get\_type} argument is an {\tt enum}:
-\begin{lstlisting}
-/* types for all group get API routines */
-typedef enum H5VL_group_get_t {
-    H5VL_GROUP_GET_GCPL,      /*group creation property list */
-    H5VL_GROUP_GET_INFO       /*group info                   */
-} H5VL_group_get_t;
+    herr_t (*close)(void *attr, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): The group object where information needs to be
-  retrieved from.\\
-  {\tt get\_type} & (IN): The type of the information to retrieve.\\
+  {\tt attr} & (IN): Pointer to the attribute object.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
-  {\tt arguments} & (IN/OUT): argument list containing parameters and
-  output pointers for the get operation. \\
 \end{tabular}
 
-The {\tt arguments} argument contains a variable list of arguments
-depending on the {\tt get\_type} parameter. The following list shows
-the argument list, in-order, for each type:
-
-\begin{itemize}
-\item {\tt H5VL\_GROUP\_GET\_GCPL}, to retrieve the group creation
-  property list of the group specified in {\tt obj}:
-  \begin{enumerate}
-  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
-    group creation property list.
-  \end{enumerate}
-
-\item {\tt H5VL\_GROUP\_GET\_INFO}, to retrieve the attribute info:
-  \begin{enumerate}
-  \item {\tt H5VL\_loc\_params\_t loc\_params} (IN): The location parameters
-    explained in section~\ref{sec:map}. 
-  \item {\tt H5G\_info\_t *ginfo} (OUT): info structure to fill the
-    group info in.
-  \end{enumerate}
-\end{itemize}
+\subsection{The Named Datatype Function Callbacks}
+The HDF5 datatype routines (H5T) allow users to create and manage HDF5
+datatypes. Those routines are divided into two categories. One that
+operates on all types of datatypes but do not modify the contents of
+the container (all in memory), and others that operate on named
+datatypes by accessing the container. When a user creates an HDF5
+datatype, it is still an object in memory space (transient datatype)
+that has not been added to the HDF5 containers. Only when a user
+commits the HDF5 datatype, it becomes persistent in the
+container. Those are called named/committed datatypes. The transient
+H5T routines should work on named datatypes nevertheless. 
 
-The {\tt close} callback in the group class should terminate access to
-the group object and free all resources it was consuming, and returns
-an {\tt herr\_t} indicating success or failure.
+All the H5T API routines that modify the HDF5 container map to one of
+the named datatype callback routines in this class that the plugin needs to
+implement:
 
-\textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*close)(void *group, hid_t dxpl_id, void **req);
-\end{lstlisting}
-
-\textbf{Arguments:}\\
-\begin{tabular}{l p{10cm}}
-  {\tt group} & (IN): Pointer to the group object.\\
-  {\tt dxpl\_id} & (IN): The data transfer property list.\\
-  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
-  operation created by the plugin.\\
-\end{tabular}
-
-\subsection{The Link Function Callbacks}
-
-The link API routines (H5L) allow HDF5 users to create and manage
-HDF5 links. All the H5L API routines that modify the HDF5 container
-map to one of the link callback routines in this class that the
-plugin needs to implement:
+typedef struct H5VL_datatype_class_t {
+    void *(*commit)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, 
+        hid_t tapl_id, hid_t dxpl_id, void **req);
 
-\begin{lstlisting}
-typedef struct H5VL_link_class_t {
-    herr_t (*create)(H5VL_link_create_type_t create_type, void *obj,
-        H5VL_loc_params_t loc_params, hid_t lcpl_id, 
-        hid_t lapl_id, hid_t dxpl_id, void **req);
+    void *(*open) (void *obj, H5VL_loc_params_t loc_params, 
+        const char * name, hid_t tapl_id, hid_t dxpl_id, void **req);
 
-    herr_t (*move)(void *src_obj, H5VL_loc_params_t loc_params1,
-        void *dst_obj, H5VL_loc_params_t loc_params2,
-        hbool_t copy_flag, hid_t lcpl, hid_t lapl, 
+    ssize_t (*get_binary)(void *obj, unsigned char *buf, size_t size, 
         hid_t dxpl_id, void **req);
 
-    herr_t (*iterate)(void *obj, H5VL_loc_params_t loc_params, 
-        hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, 
-        hsize_t *idx, H5L_iterate_t op, void *op_data, hid_t dxpl_id, 
-        void **req);
-
-    herr_t (*get)(void *obj, H5VL_loc_params_t loc_params, 
-        H5VL_link_get_t get_type, hid_t dxpl_id, void **req, 
-        va_list arguments);
+    herr_t (*get) (void *obj, H5VL_datatype_get_t get_type, 
+        hid_t dxpl_id, void **req, va_list arguments);
 
-    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, 
-        hid_t dxpl_id, void **req);
-} H5VL_link_class_t;
+    herr_t (*close) (void *dt, hid_t dxpl_id, void **req);
+} H5VL_datatype_class_t;
 \end{lstlisting}
 
-
-The {\tt create} callback in the group class should create a hard,
-soft, external, or user-defined links in the container. It returns an
-{\tt herr\_t} indicating success or failure.
+The {\tt commit} callback in the named datatype class should create a datatype object in the container of the location object and
+returns a pointer to the datatype structure containing information to
+access the datatype in future calls. 
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*create)(H5VL_link_create_type_t create_type, void *obj,
-        H5VL_loc_params_t loc_params, hid_t lcpl_id, 
-        hid_t lapl_id, hid_t dxpl_id, void **req);
-\end{lstlisting}
-
-The {\tt create\_type} argument is an {\tt enum}:
-\begin{lstlisting}
-/* link create types for VOL */
-typedef enum H5VL_link_create_type_t {
-    H5VL_LINK_CREATE_HARD,  /* Hard Link          */
-    H5VL_LINK_CREATE_SOFT,  /* Soft Link          */
-    H5VL_LINK_CREATE_UD     /* External / UD Link */
-} H5VL_link_create_type_t;
+    void *(*commit)(void *obj, H5VL_loc_params_t loc_params, 
+        const char *name, hid_t type_id, hid_t lcpl_id, hid_t tcpl_id, 
+        hid_t tapl_id, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt create\_type} & (IN): type of the link to be created.\\
-  {\tt obj} & (IN): Pointer to an object where the link needs to be
-  created from.\\
+  {\tt obj} & (IN): Pointer to an object where the datatype needs
+  to be committed or where the look-up of the target object needs to
+  start.\\
   {\tt loc\_params} & (IN): The location parameters as explained in
-  section~\ref{sec:map} for the source object. \\
-  {\tt lcpl\_id} & (IN): The link creation property list. It contains
-  all the link creation properties in addition to other API parameters
-  depending on the creation type, which will be detailed next.\\
-  {\tt lapl\_id} & (IN): The link access property list.\\
+  section~\ref{sec:map}. In this call, the location type is always {\tt
+    H5VL\_OBJECT\_BY\_SELF}. \\
+  {\tt name} & (IN): The name of the datatype to be created.\\
+  {\tt type\_id} & (IN): The transient datatype identifier to be
+  committed. \\
+  {\tt lcpl\_id} & (IN): The link creation property list. \\
+  {\tt tcpl\_id} & (IN): The datatype creation property list.\\
+  {\tt tapl\_id} & (IN): The datatype access property list.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-As mentioned in the argument list, the {\tt lcpl\_id} contains the
-parameters for the link creation operation depending on the creation
-type:
-\begin{itemize}
-\item {\tt H5VL\_LINK\_CREATE\_HARD} contains two properties:
-  \begin{enumerate}
-  \item {\tt H5VL\_LINK\_TARGET} (with type {\tt void*}): The target
-    object where the hard link needs to be created to.
-  \item {\tt H5VL\_LINK\_TARGET\_LOC\_PARAMS} (with type {\tt
-      H5VL\_loc\_params\_t}): The location parameters as explained in
-    section~\ref{sec:map} for the target object.
-  \end{enumerate}
-
-\item {\tt H5VL\_LINK\_CREATE\_SOFT} contains one property:
-  \begin{enumerate}
-  \item {\tt H5VL\_LINK\_TARGET\_NAME} (with type {\tt char*}): The target
-    link where the soft link should point to.
-  \end{enumerate}
-
-\item {\tt H5VL\_LINK\_CREATE\_UD} contains two properties:
-  \begin{enumerate}
-  \item {\tt H5VL\_LINK\_TYPE} (with type {\tt H5L\_type\_t}): The
-    user defined link class. {\tt H5L\_TYPE\_EXTERNAL} suggests an
-    external link is to be created.
-  \item {\tt H5VL\_LINK\_UDATA} (with type {\tt void*}): User supplied
-    link information (contains the external link buffer for external
-    links). 
-  \item {\tt H5VL\_LINK\_UDATA\_SIZE} (with type {\tt size\_t}): size
-    of the {\tt udata} buffer. 
-  \end{enumerate}
-\end{itemize}
-
-The {\tt move} callback in the link class should copy or move a link
-within the HDF5 container. It returns an {\tt herr\_t} indicating
-success or failure.
+The {\tt open} callback in the named datatype class should open a
+previously committed datatype object in the container of the location
+object and returns a pointer to the datatype structure containing
+information to access the datatype in future calls.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*move)(void *src_obj, H5VL_loc_params_t loc_params1,
-        void *dst_obj, H5VL_loc_params_t loc_params2,
-        hbool_t copy_flag, hid_t lcpl, hid_t lapl, 
-        hid_t dxpl_id, void **req);
+    void *(*open) (void *obj, H5VL_loc_params_t loc_params, 
+        const char * name, hid_t tapl_id, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt src\_obj} & (IN): original/source object or file. \\
-  {\tt loc\_params1} & (IN): The location parameters for the source
-  object as explained in section~\ref{sec:map}. The type can be only {\tt
-    H5VL\_OBJECT\_BY\_NAME} in this callback. \\
-  {\tt dst\_obj} & (IN): destination object or file. \\
-  {\tt loc\_params1} & (IN): The location parameters for the destination
-  object as explained in section~\ref{sec:map}. The type can be only {\tt
-    H5VL\_OBJECT\_BY\_NAME} in this callback. \\
-  {\tt copy\_flag} & (IN): flag to indicate whether link is to be
-  copied (value 1) or moved (value 0).\\
-  {\tt lcpl\_id} & (IN): The link creation property list.\\
-  {\tt lapl\_id} & (IN): The link access property list.\\
+  {\tt obj} & (IN): Pointer to an object where the datatype needs
+  to be opened or where the look-up of the target object needs to
+  start.\\
+  {\tt loc\_params} & (IN): The location parameters as explained in
+  section~\ref{sec:map}. In this call, the location type is always {\tt
+    H5VL\_OBJECT\_BY\_SELF}. \\
+  {\tt name} & (IN): The name of the datatype to be opened.\\
+  {\tt tapl\_id} & (IN): The datatype access property list.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt iterate} callback in the link class should iterate over links
-in a group and apply a user defined routine. It returns an {\tt
-  herr\_t} indicating success or failure.
+The {\tt get\_binary} callback in the named datatype class should
+serialize the original transient HDF5 datatype that was committed, or
+return the size that is required for it be serialized if the passed in
+buffer is {\tt NULL}. The HDF5 library provides two functions to
+encode and decode datatypes in their transient form, {\tt H5Tencode()}
+and {\tt H5Tdecode()}. When a datatype is committed, the plugin is
+required to keep the serialized form of the transient datatype stored
+somewhere in the container (which is usually the case anyway when
+committing a named datatype), so it can be retrieved with this
+call. This is needed to generate the higher level HDF5 datatype
+identifier that allows all the H5T ``transient'' routines to work
+properly on the named datatype.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*iterate)(void *obj, H5VL_loc_params_t loc_params, 
-        hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, 
-        hsize_t *idx, H5L_iterate_t op, void *op_data, hid_t dxpl_id, 
-        void **req);
+    ssize_t (*get_binary)(void *obj, unsigned char *buf, size_t size, 
+        hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): object where to start iteration or where the
-  lookup for the target object needs to start. \\
-  {\tt loc\_params} & (IN): The location parameters for the source
-  object as explained in section~\ref{sec:map}. The type can be only {\tt
-    H5VL\_OBJECT\_BY\_NAME} or {\tt H5VL\_OBJECT\_BY\_SELF} in this
-  callback.\\ 
-  {\tt recursive} & (IN): whether to recursively follow links into
-  subgroups of the specified group.\\
-  {\tt idx\_type} & (IN): Type of index which determines the order.\\
-  {\tt idx} & (IN/OUT): iteration position where to start and return
-  position where an interrupted iteration may restart.\\
-  {\tt op} & (IN): User-defined function for the iterator.\\
-  {\tt op\_data} & (IN/OUT): User data to pass through to and to be
-  returned by iterator operator function.\\
+  {\tt obj} & (IN): Pointer to the named datatype object.\\
+  {\tt buf} & (OUT): Buffer to out the binary form of the datatype in.\\
+  {\tt size} & (IN): The size of the buffer passed in (0 if NULL).\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
 \end{tabular}
 
-The {\tt get} callback in the link class should retrieve information
-about links as specified in the {\tt get\_type} parameter. It
-returns an {\tt herr\_t} indicating success or failure.
+The {\tt get} callback in the named datatype class should retrieve
+information about the named datatype as specified in the {\tt get\_type}
+parameter.It returns an {\tt herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*get)(void *obj, H5VL_loc_params_t loc_params, 
-        H5VL_link_get_t get_type, hid_t dxpl_id, void **req, 
-        va_list arguments);
+    herr_t (*get) (void *obj, H5VL_datatype_get_t get_type, 
+        hid_t dxpl_id, void **req, va_list arguments);
 \end{lstlisting}
 
 The {\tt get\_type} argument is an {\tt enum}:
 \begin{lstlisting}
-/* types for all link get API routines */
-typedef enum H5VL_link_get_t {
-    H5VL_LINK_EXISTS,          /* link existence  */
-    H5VL_LINK_GET_INFO,        /* link info       */
-    H5VL_LINK_GET_NAME,        /* link name       */
-    H5VL_LINK_GET_VAL          /* link value      */
-} H5VL_link_get_t;
+/* types for all datatype get API routines */
+typedef enum H5VL_datatype_get_t {
+    H5VL_DATATYPE_GET_TCPL   /*datatype creation property list */
+} H5VL_datatype_get_t;
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): The file or group object where information needs to be
-  retrieved from.\\
-  {\tt loc\_params} & (IN): The location parameters for the source
-  object as explained in section~\ref{sec:map}. The type can be only {\tt
-    H5VL\_OBJECT\_BY\_NAME} or {\tt H5VL\_OBJECT\_BY\_IDX} in this
-  callback.\\ 
+  {\tt obj} & (IN): The named datatype to retrieve information from.\\
   {\tt get\_type} & (IN): The type of the information to retrieve.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
@@ -1709,58 +1473,26 @@ depending on the {\tt get\_type} parameter. The following list shows
 the argument list, in-order, for each type:
 
 \begin{itemize}
-\item {\tt H5VL\_LINK\_EXITS}, to determine whether the link specified
-  in the {\tt loc\_params} exits ({\tt loc\_params} is of type {\tt
-    H5VL\_OBJECT\_BY\_NAME} only with this type):
-  \begin{enumerate}
-  \item {\tt htri\_t *ret} (OUT): buffer for the existence of the link
-    (0 for no, 1 for yes).
-  \end{enumerate}
-
-\item {\tt H5VL\_LINK\_GET\_INFO}, to retrieve the link info from the
-  link specified in the {\tt loc\_params}:
-  \begin{enumerate}
-  \item {\tt H5L\_info\_t linfo} (OUT): pointer to info structure to
-    fill.
-  \end{enumerate}
-
-\item {\tt H5VL\_LINK\_GET\_NAME}, to retrieve the name of the link
-  specified by the index information in {\tt loc\_params} ({\tt
-    loc\_params} is of type {\tt H5VL\_OBJECT\_BY\_IDX} only with this
-  type):
-  \begin{enumerate}
-  \item {\tt char* name} (OUT): buffer to copy the name into.
-  \item {\tt size\_t size} (IN): size of the buffer name, if 0, return
-    only the buffer size needed.
-  \item {\tt ssize\_t *ret} (OUT): buffer to return the length of the
-    link name.
-  \end{enumerate}
-
-\item {\tt H5VL\_LINK\_GET\_VAL}, to retrieve the link value from the
-  link specified in the {\tt loc\_params}:
+\item {\tt H5VL\_DATATYPE\_GET\_TCPL}, to retrieve the datatype
+  creation property list:
   \begin{enumerate}
-  \item {\tt void *buf} (OUT): buffer to put the value into.
-  \item {\tt size\_t size} (IN): size of the passed in buffer.
+  \item {\tt hid\_t *ret\_id} (OUT): buffer for the identifier of the
+    type creation property list.
   \end{enumerate}
-
 \end{itemize}
 
-The {\tt remove} callback in the link class should remove a link from
-an HDF5 container, and returns an {\tt herr\_t} indicating success or
-failure.
+The {\tt close} callback in the named datatype class should terminate
+access to the datatype object and free all resources it was
+consuming, and returns an {\tt herr\_t} indicating success or failure.
 
 \textbf{Signature:}
 \begin{lstlisting}
-    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, 
-        hid_t dxpl_id, void **req);
+    herr_t (*close) (void *dt, hid_t dxpl_id, void **req);
 \end{lstlisting}
 
 \textbf{Arguments:}\\
 \begin{tabular}{l p{10cm}}
-  {\tt obj} & (IN): group object or file containing the link.\\
-  {\tt loc\_params} & (IN): The location parameters for the link to be
-  deleted.The type can be only {\tt H5VL\_OBJECT\_BY\_NAME} or {\tt
-    H5VL\_OBJECT\_BY\_IDX} in this callback.\\ 
+  {\tt dt} & (IN): Pointer to the datatype object.\\
   {\tt dxpl\_id} & (IN): The data transfer property list.\\
   {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
   operation created by the plugin.\\
@@ -2071,6 +1803,271 @@ the argument list, in-order, for each type:
   \end{enumerate}
 \end{itemize}
 
+\subsection{The Link Function Callbacks}
+The link API routines (H5L) allow HDF5 users to create and manage
+HDF5 links. All the H5L API routines that modify the HDF5 container
+map to one of the link callback routines in this class that the
+plugin needs to implement:
+
+\begin{lstlisting}
+typedef struct H5VL_link_class_t {
+    herr_t (*create)(H5VL_link_create_type_t create_type, void *obj,
+        H5VL_loc_params_t loc_params, hid_t lcpl_id, 
+        hid_t lapl_id, hid_t dxpl_id, void **req);
+
+    herr_t (*move)(void *src_obj, H5VL_loc_params_t loc_params1,
+        void *dst_obj, H5VL_loc_params_t loc_params2,
+        hbool_t copy_flag, hid_t lcpl, hid_t lapl, 
+        hid_t dxpl_id, void **req);
+
+    herr_t (*iterate)(void *obj, H5VL_loc_params_t loc_params, 
+        hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, 
+        hsize_t *idx, H5L_iterate_t op, void *op_data, hid_t dxpl_id, 
+        void **req);
+
+    herr_t (*get)(void *obj, H5VL_loc_params_t loc_params, 
+        H5VL_link_get_t get_type, hid_t dxpl_id, void **req, 
+        va_list arguments);
+
+    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, 
+        hid_t dxpl_id, void **req);
+} H5VL_link_class_t;
+\end{lstlisting}
+
+
+The {\tt create} callback in the group class should create a hard,
+soft, external, or user-defined links in the container. It returns an
+{\tt herr\_t} indicating success or failure.
+
+\textbf{Signature:}
+\begin{lstlisting}
+    herr_t (*create)(H5VL_link_create_type_t create_type, void *obj,
+        H5VL_loc_params_t loc_params, hid_t lcpl_id, 
+        hid_t lapl_id, hid_t dxpl_id, void **req);
+\end{lstlisting}
+
+The {\tt create\_type} argument is an {\tt enum}:
+\begin{lstlisting}
+/* link create types for VOL */
+typedef enum H5VL_link_create_type_t {
+    H5VL_LINK_CREATE_HARD,  /* Hard Link          */
+    H5VL_LINK_CREATE_SOFT,  /* Soft Link          */
+    H5VL_LINK_CREATE_UD     /* External / UD Link */
+} H5VL_link_create_type_t;
+\end{lstlisting}
+
+\textbf{Arguments:}\\
+\begin{tabular}{l p{10cm}}
+  {\tt create\_type} & (IN): type of the link to be created.\\
+  {\tt obj} & (IN): Pointer to an object where the link needs to be
+  created from.\\
+  {\tt loc\_params} & (IN): The location parameters as explained in
+  section~\ref{sec:map} for the source object. \\
+  {\tt lcpl\_id} & (IN): The link creation property list. It contains
+  all the link creation properties in addition to other API parameters
+  depending on the creation type, which will be detailed next.\\
+  {\tt lapl\_id} & (IN): The link access property list.\\
+  {\tt dxpl\_id} & (IN): The data transfer property list.\\
+  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
+  operation created by the plugin.\\
+\end{tabular}
+
+As mentioned in the argument list, the {\tt lcpl\_id} contains the
+parameters for the link creation operation depending on the creation
+type:
+\begin{itemize}
+\item {\tt H5VL\_LINK\_CREATE\_HARD} contains two properties:
+  \begin{enumerate}
+  \item {\tt H5VL\_LINK\_TARGET} (with type {\tt void*}): The target
+    object where the hard link needs to be created to.
+  \item {\tt H5VL\_LINK\_TARGET\_LOC\_PARAMS} (with type {\tt
+      H5VL\_loc\_params\_t}): The location parameters as explained in
+    section~\ref{sec:map} for the target object.
+  \end{enumerate}
+
+\item {\tt H5VL\_LINK\_CREATE\_SOFT} contains one property:
+  \begin{enumerate}
+  \item {\tt H5VL\_LINK\_TARGET\_NAME} (with type {\tt char*}): The target
+    link where the soft link should point to.
+  \end{enumerate}
+
+\item {\tt H5VL\_LINK\_CREATE\_UD} contains two properties:
+  \begin{enumerate}
+  \item {\tt H5VL\_LINK\_TYPE} (with type {\tt H5L\_type\_t}): The
+    user defined link class. {\tt H5L\_TYPE\_EXTERNAL} suggests an
+    external link is to be created.
+  \item {\tt H5VL\_LINK\_UDATA} (with type {\tt void*}): User supplied
+    link information (contains the external link buffer for external
+    links). 
+  \item {\tt H5VL\_LINK\_UDATA\_SIZE} (with type {\tt size\_t}): size
+    of the {\tt udata} buffer. 
+  \end{enumerate}
+\end{itemize}
+
+The {\tt move} callback in the link class should copy or move a link
+within the HDF5 container. It returns an {\tt herr\_t} indicating
+success or failure.
+
+\textbf{Signature:}
+\begin{lstlisting}
+    herr_t (*move)(void *src_obj, H5VL_loc_params_t loc_params1,
+        void *dst_obj, H5VL_loc_params_t loc_params2,
+        hbool_t copy_flag, hid_t lcpl, hid_t lapl, 
+        hid_t dxpl_id, void **req);
+\end{lstlisting}
+
+\textbf{Arguments:}\\
+\begin{tabular}{l p{10cm}}
+  {\tt src\_obj} & (IN): original/source object or file. \\
+  {\tt loc\_params1} & (IN): The location parameters for the source
+  object as explained in section~\ref{sec:map}. The type can be only {\tt
+    H5VL\_OBJECT\_BY\_NAME} in this callback. \\
+  {\tt dst\_obj} & (IN): destination object or file. \\
+  {\tt loc\_params1} & (IN): The location parameters for the destination
+  object as explained in section~\ref{sec:map}. The type can be only {\tt
+    H5VL\_OBJECT\_BY\_NAME} in this callback. \\
+  {\tt copy\_flag} & (IN): flag to indicate whether link is to be
+  copied (value 1) or moved (value 0).\\
+  {\tt lcpl\_id} & (IN): The link creation property list.\\
+  {\tt lapl\_id} & (IN): The link access property list.\\
+  {\tt dxpl\_id} & (IN): The data transfer property list.\\
+  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
+  operation created by the plugin.\\
+\end{tabular}
+
+The {\tt iterate} callback in the link class should iterate over links
+in a group and apply a user defined routine. It returns an {\tt
+  herr\_t} indicating success or failure.
+
+\textbf{Signature:}
+\begin{lstlisting}
+    herr_t (*iterate)(void *obj, H5VL_loc_params_t loc_params, 
+        hbool_t recursive, H5_index_t idx_type, H5_iter_order_t order, 
+        hsize_t *idx, H5L_iterate_t op, void *op_data, hid_t dxpl_id, 
+        void **req);
+\end{lstlisting}
+
+\textbf{Arguments:}\\
+\begin{tabular}{l p{10cm}}
+  {\tt obj} & (IN): object where to start iteration or where the
+  lookup for the target object needs to start. \\
+  {\tt loc\_params} & (IN): The location parameters for the source
+  object as explained in section~\ref{sec:map}. The type can be only {\tt
+    H5VL\_OBJECT\_BY\_NAME} or {\tt H5VL\_OBJECT\_BY\_SELF} in this
+  callback.\\ 
+  {\tt recursive} & (IN): whether to recursively follow links into
+  subgroups of the specified group.\\
+  {\tt idx\_type} & (IN): Type of index which determines the order.\\
+  {\tt idx} & (IN/OUT): iteration position where to start and return
+  position where an interrupted iteration may restart.\\
+  {\tt op} & (IN): User-defined function for the iterator.\\
+  {\tt op\_data} & (IN/OUT): User data to pass through to and to be
+  returned by iterator operator function.\\
+  {\tt dxpl\_id} & (IN): The data transfer property list.\\
+  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
+  operation created by the plugin.\\
+\end{tabular}
+
+The {\tt get} callback in the link class should retrieve information
+about links as specified in the {\tt get\_type} parameter. It
+returns an {\tt herr\_t} indicating success or failure.
+
+\textbf{Signature:}
+\begin{lstlisting}
+    herr_t (*get)(void *obj, H5VL_loc_params_t loc_params, 
+        H5VL_link_get_t get_type, hid_t dxpl_id, void **req, 
+        va_list arguments);
+\end{lstlisting}
+
+The {\tt get\_type} argument is an {\tt enum}:
+\begin{lstlisting}
+/* types for all link get API routines */
+typedef enum H5VL_link_get_t {
+    H5VL_LINK_EXISTS,          /* link existence  */
+    H5VL_LINK_GET_INFO,        /* link info       */
+    H5VL_LINK_GET_NAME,        /* link name       */
+    H5VL_LINK_GET_VAL          /* link value      */
+} H5VL_link_get_t;
+\end{lstlisting}
+
+\textbf{Arguments:}\\
+\begin{tabular}{l p{10cm}}
+  {\tt obj} & (IN): The file or group object where information needs to be
+  retrieved from.\\
+  {\tt loc\_params} & (IN): The location parameters for the source
+  object as explained in section~\ref{sec:map}. The type can be only {\tt
+    H5VL\_OBJECT\_BY\_NAME} or {\tt H5VL\_OBJECT\_BY\_IDX} in this
+  callback.\\ 
+  {\tt get\_type} & (IN): The type of the information to retrieve.\\
+  {\tt dxpl\_id} & (IN): The data transfer property list.\\
+  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
+  operation created by the plugin.\\
+  {\tt arguments} & (IN/OUT): argument list containing parameters and
+  output pointers for the get operation. \\
+\end{tabular}
+
+The {\tt arguments} argument contains a variable list of arguments
+depending on the {\tt get\_type} parameter. The following list shows
+the argument list, in-order, for each type:
+
+\begin{itemize}
+\item {\tt H5VL\_LINK\_EXITS}, to determine whether the link specified
+  in the {\tt loc\_params} exits ({\tt loc\_params} is of type {\tt
+    H5VL\_OBJECT\_BY\_NAME} only with this type):
+  \begin{enumerate}
+  \item {\tt htri\_t *ret} (OUT): buffer for the existence of the link
+    (0 for no, 1 for yes).
+  \end{enumerate}
+
+\item {\tt H5VL\_LINK\_GET\_INFO}, to retrieve the link info from the
+  link specified in the {\tt loc\_params}:
+  \begin{enumerate}
+  \item {\tt H5L\_info\_t linfo} (OUT): pointer to info structure to
+    fill.
+  \end{enumerate}
+
+\item {\tt H5VL\_LINK\_GET\_NAME}, to retrieve the name of the link
+  specified by the index information in {\tt loc\_params} ({\tt
+    loc\_params} is of type {\tt H5VL\_OBJECT\_BY\_IDX} only with this
+  type):
+  \begin{enumerate}
+  \item {\tt char* name} (OUT): buffer to copy the name into.
+  \item {\tt size\_t size} (IN): size of the buffer name, if 0, return
+    only the buffer size needed.
+  \item {\tt ssize\_t *ret} (OUT): buffer to return the length of the
+    link name.
+  \end{enumerate}
+
+\item {\tt H5VL\_LINK\_GET\_VAL}, to retrieve the link value from the
+  link specified in the {\tt loc\_params}:
+  \begin{enumerate}
+  \item {\tt void *buf} (OUT): buffer to put the value into.
+  \item {\tt size\_t size} (IN): size of the passed in buffer.
+  \end{enumerate}
+
+\end{itemize}
+
+The {\tt remove} callback in the link class should remove a link from
+an HDF5 container, and returns an {\tt herr\_t} indicating success or
+failure.
+
+\textbf{Signature:}
+\begin{lstlisting}
+    herr_t (*remove)(void *obj, H5VL_loc_params_t loc_params, 
+        hid_t dxpl_id, void **req);
+\end{lstlisting}
+
+\textbf{Arguments:}\\
+\begin{tabular}{l p{10cm}}
+  {\tt obj} & (IN): group object or file containing the link.\\
+  {\tt loc\_params} & (IN): The location parameters for the link to be
+  deleted.The type can be only {\tt H5VL\_OBJECT\_BY\_NAME} or {\tt
+    H5VL\_OBJECT\_BY\_IDX} in this callback.\\ 
+  {\tt dxpl\_id} & (IN): The data transfer property list.\\
+  {\tt req} & (IN/OUT): A pointer to the asynchronous request of the
+  operation created by the plugin.\\
+\end{tabular}
+
 \subsection{The Asynchronous Function Callbacks}
 As of now, the HDF5 library does not provide asynchronous API
 operations. An asynchronous class to manage asynchronous operations