1 files changed, 79 insertions, 2 deletions
diff --git a/src/H5Imodule.h b/src/H5Imodule.h
index 8db31c8..08f8bb0 100644
--- a/src/H5Imodule.h
+++ b/src/H5Imodule.h
@@ -30,8 +30,85 @@
 #define H5_MY_PKG_INIT NO
 
 /**\defgroup H5I H5I
- * \brief Identifier Interface
- * \todo Describe concisely what the functions in this module are about.
+ *
+ * Use the functions in this module to manage identifiers defined by the HDF5
+ * library. See \ref H5IUD for user-defined identifiers and identifier
+ * types.
+ *
+ * HDF5 identifiers are usually created as a side-effect of creating HDF5
+ * entities such as groups, datasets, attributes, or property lists.
+ *
+ * Identifiers defined by the HDF5 library can be used to retrieve information
+ * such as path names and reference counts, and their validity can be checked.
+ *
+ * Identifiers can be updated by manipulating their reference counts.
+ *
+ * Unused identifiers should be reclaimed by closing the associated item, e.g.,
+ * HDF5 object, or decrementing the reference count to 0.
+ *
+ * \note Identifiers (of type \ref hid_t) are run-time auxiliaries and
+ * not persisted in the file.
+ *
+ * <table>
+ * <tr><th>Create</th><th>Read</th></tr>
+ * <tr valign="top">
+ *   <td>
+ *   \snippet{lineno} H5I_examples.c create
+ *   </td>
+ *   <td>
+ *   \snippet{lineno} H5I_examples.c read
+ *   </td>
+ * <tr><th>Update</th><th>Delete</th></tr>
+ * <tr valign="top">
+ *   <td>
+ *   \snippet{lineno} H5I_examples.c update
+ *   </td>
+ *   <td>
+ *   \snippet{lineno} H5I_examples.c delete
+ *   </td>
+ * </tr>
+ * </table>
+ *
+ * \defgroup H5IUD User-defined ID Types
+ * \ingroup H5I
+ *
+ * The \ref H5I module contains functions to define new identifier types.
+ * For convenience, handles of type \ref hid_t can then be associated with the
+ * new identifier types and user objects.
+ *
+ * New identifier types can be created by registering a new identifier type
+ * with the HDF5 library. Once a new identifier type has bee registered,
+ * it can be used to generate identifiers for user objects.
+ *
+ * User-defined identifier types can be searched and iterated.
+ *
+ * Like library-defined identifiers, user-defined identifiers \Emph{and}
+ * identifier types are reference counted, and the reference counts can be
+ * manipulated accordingly.
+ *
+ * User-defined identifiers no longer in use should be deleted or reclaimed,
+ * and identifier types should be destroyed if they are no longer required.
+ *
+ * <table>
+ * <tr><th>Create</th><th>Read</th></tr>
+ * <tr valign="top">
+ *   <td>
+ *   \snippet{lineno} H5I_examples.c create_ud
+ *   </td>
+ *   <td>
+ *   \snippet{lineno} H5I_examples.c read_ud
+ *   </td>
+ * <tr><th>Update</th><th>Delete</th></tr>
+ * <tr valign="top">
+ *   <td>
+ *   \snippet{lineno} H5I_examples.c update_ud
+ *   </td>
+ *   <td>
+ *   \snippet{lineno} H5I_examples.c delete_ud
+ *   </td>
+ * </tr>
+ * </table>
+ *
  */
 
 #endif /* H5Imodule_H */