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<html>
<head><title>
HDF5/H5F API Specification
</title>

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<center>
<table border=0 width=98%>
<tr><td valign=top align=left>
<a href="index.html">HDF5 documents and links</a>&nbsp;<br>
<a href="H5.intro.html">Introduction to HDF5</a>&nbsp;<br>
<a href="http://hdf.ncsa.uiuc.edu/HDF5/doc/UG/index.html">HDF5 User Guide</a>&nbsp;<br>
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</td>
<td valign=top align=right>
And in this document, the 
<a href="RM_H5Front.html">HDF5 Reference Manual</a>&nbsp;&nbsp;
<br>
<a href="RM_H5.html">H5</a>&nbsp;&nbsp;
<a href="RM_H5A.html">H5A</a>&nbsp;&nbsp;
<a href="RM_H5D.html">H5D</a>&nbsp;&nbsp;
<a href="RM_H5E.html">H5E</a>&nbsp;&nbsp;
<a href="RM_H5F.html">H5F</a>&nbsp;&nbsp;
<a href="RM_H5G.html">H5G</a>&nbsp;&nbsp;
<a href="RM_H5I.html">H5I</a>&nbsp;&nbsp;
<a href="RM_H5P.html">H5P</a>&nbsp;&nbsp;
<br>
<a href="RM_H5R.html">H5R</a>&nbsp;&nbsp;
<a href="RM_H5S.html">H5S</a>&nbsp;&nbsp;
<a href="RM_H5T.html">H5T</a>&nbsp;&nbsp;
<a href="RM_H5Z.html">H5Z</a>&nbsp;&nbsp;
<a href="Tools.html">Tools</a>&nbsp;&nbsp;
<a href="PredefDTypes.html">Datatypes</a>&nbsp;&nbsp;
</td></tr>
</table>
</center>
<hr><!-- #EndLibraryItem --><center>
<h1>H5F: File Interface</h1>
</center>

<h2>File API Functions</h2>

These functions are designed to provide file-level access to HDF5 files.
Further manipulation of objects inside a file is performed through one of APIs
documented below.

<p>
<strong>The C Interfaces:</strong>

<table border=0>
<tr><td valign=top>
<ul>
    <li><a href="#File-Create">H5Fcreate</a>
    <li><a href="#File-Open">H5Fopen</a>
    <li><a href="#File-Reopen">H5Freopen</a>
    <li><a href="#File-Close">H5Fclose</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
    <li><a href="#File-Flush">H5Fflush</a>
    <li><a href="#File-IsHDF5">H5Fis_hdf5</a>
    <li><a href="#File-Mount">H5Fmount</a>
    <li><a href="#File-Unmount">H5Funmount</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
    <li><a href="#File-GetVfdHandle">H5Fget_vfd_handle</a>
    <li><a href="#File-GetCreatePlist">H5Fget_create_plist</a>
    <li><a href="#File-GetAccessPlist">H5Fget_access_plist</a>
    <li><a href="#File-GetObjCount">H5Fget_obj_count</a>
    <li><a href="#File-GetObjIDs">H5Fget_obj_ids</a>
</ul>
</td></tr>
</table>
<br>

<i>Alphabetical Listing</i>

<table border="0">
  <tr>
    <td valign="top">
	<ul>
      <li><a href="#File-Close">H5Fclose</a>
      <li><a href="#File-Create">H5Fcreate</a>
      <li><a href="#File-Flush">H5Fflush</a>
      <li><a href="#File-GetAccessPlist">H5Fget_access_plist</a>
      <li><a href="#File-GetCreatePlist">H5Fget_create_plist</a>
    </ul>      
    </td>
    
    <td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
    
    <td valign="top">
	<ul>
      <li><a href="#File-GetObjCount">H5Fget_obj_count</a>
      <li><a href="#File-GetObjIDs">H5Fget_obj_ids</a>
      <li><a href="#File-GetVfdHandle">H5Fget_vfd_handle</a>
      <li><a href="#File-IsHDF5">H5Fis_hdf5</a>
      <li><a href="#File-Mount">H5Fmount</a>
	</ul>
    </td>
    
    <td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td>
    
    <td valign="top">
	<ul>
      <li><a href="#File-Open">H5Fopen</a>
      <li><a href="#File-Reopen">H5Freopen</a>
      <li><a href="#File-Unmount">H5Funmount</a>
	</ul>
    </td>
  </tr>
</table>

<br>
<strong>The FORTRAN90 Interfaces:</strong>

<br>
<font size=-1>
<i>In general, each FORTRAN90 subroutine performs exactly the same task 
as the corresponding C function.  The links below (electronic versions only) go to the C function 
descriptions, which serve as general descriptions for both.  A button, 
under <strong>Non-C API(s)</strong> at the end of the C function description,
opens an external browser window displaying the FORTRAN90-specific 
information.  You will probably want to adjust the size and location of 
this external window so that both browser windows are visible and to 
facilitate moving easily between them.</i>
</font><br>

<table border=0>
<tr><td valign=top>
<ul>
    <li><a href="#File-Create">h5fcreate_f</a>
    <li><a href="#File-Open">h5fopen_f</a>
    <li><a href="#File-Reopen">h5freopen_f</a>
    <li><a href="#File-Close">h5fclose_f</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
    <li><a href="#File-Flush">h5fflush_f</a>
    <li><a href="#File-IsHDF5">h5fis_hdf5_f</a>
    <li><a href="#File-Mount">h5fmount_f</a>
    <li><a href="#File-Unmount">h5funmount_f</a>
</ul>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
<ul>
    <li><a href="#File-GetVfdHandle">h5fget_vfd_handle_f</a>
    <li><a href="#File-GetCreatePlist">h5fget_create_plist_f</a>
    <li><a href="#File-GetAccessPlist">h5fget_access_plist_f</a>
    <li><a href="#File-GetObjCount">h5fget_obj_count_f</a>
    <li><a href="#File-GetObjIDs">h5fget_obj_ids_f</a>
</ul>
</td></tr>
</table>

<!-- NEW PAGE -->
<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fclose" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-Close">H5Fclose</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Fclose</code>(<em>hid_t</em> <code>file_id</code>
        )
<dt><strong>Purpose:</strong>
        <dd>Terminates access to an HDF5 file.  
<dt><strong>Description:</strong>
        <dd><code>H5Fclose</code> terminates access to an HDF5 file
            by flushing all data to storage and terminating access
            to the file through <code>file_id</code>.  
            <p>
            If this is the last file identifier open for the file 
            and no other access identifier is open (e.g., a dataset 
            identifier, group identifier, or shared datatype identifier),
            the file will be fully closed and access will end.
            <p>
            <strong>Delayed close:</strong> 
            <br>
            Note the following deviation from the above-described behavior.
            If <code>H5Fclose</code> is called for a file but one or more 
            objects within the file remain open, those objects will remain 
            accessible until they are individually closed.  
            Thus, if the dataset <code>data_sample</code> is open when 
            <code>H5Fclose</code> is called for the file containing it, 
            <code>data_sample</code> will remain open and accessible 
            (including writable) until it is explicitely closed.  
            The file will be automatically closed once all objects in the
            file have been closed.
            <p>
            Be warned, hoever, that there are circumstances where it is 
            not possible to delay closing a file.  
            For example, an MPI-IO file close is a collective call; all of
            the processes that opened the file must close it collectively.
            The file cannot be closed at some time in the future by each 
            process in an independent fashion.
            Another example is that an application using an AFS token-based 
            file access privilage may destroy its AFS token after 
            <code>H5Fclose</code> has returned successfully.  
            This would make any future access to the file, or any object 
            within it, illegal. 
            <p>
            In such situations, applications must close all open objects 
            in a file before calling <code>H5Fclose</code>.  
            It is generally recommended to do so in all cases.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>file_id</code>
            <dd>IN: Identifier of a file to terminate access to.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fclose_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fcreate" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-Create">H5Fcreate</a>
<dt><strong>Signature:</strong>
    <dd><em>hid_t </em><code>H5Fcreate</code>(<em>const char *</em><code>name</code>,
            <em>unsigned</em> <code>flags</code>,
            <em>hid_t</em> <code>create_id</code>,
            <em>hid_t</em> <code>access_id</code>
        )
<dt><strong>Purpose:</strong>
        <dd>Creates HDF5 files.
<dt><strong>Description:</strong>
        <dd><code>H5Fcreate</code> is the primary function for creating 
            HDF5 files . 
            <p>
            The <code>flags</code> parameter determines whether an 
            existing file will be overwritten.  All newly created files 
            are opened for both reading and writing.  All flags may be 
            combined with the bit-wise OR operator (`|') to change 
            the behavior of the <code>H5Fcreate</code> call.
            <p>
            The more complex behaviors of file creation and access
            are controlled through the file-creation and file-access
            property lists.  The value of <code>H5P_DEFAULT</code> for 
            a property list value indicates that the library should use
            the default values for the appropriate property list.
            <p>
            The return value is a file identifier for the newly-created file;
            this file identifier should be closed by calling 
            <code>H5Fclose</code> when it is no longer needed. 
            <p>

            <b>Special case -- File creation in the case of an 
            already-open file:</b>
            <br>
            If a file being created is already opened, by either a 
            previous <code>H5Fopen</code> or <code>H5Fcreate</code> call, 
            the HDF5 library may or may not detect that the open file and 
            the new file are the same physical file. 
            (See <a href="#File-Open"><code>H5Fopen</code></a> regarding 
            the limitations in detecting the re-opening of an already-open 
            file.) 
            <p>
            If the library detects that the file is already opened, 
            <code>H5Fcreate</code> will return a failure, regardless 
            of the use of <code>H5F_ACC_TRUNC</code>.
            <p>
            If the library does not detect that the file is already opened 
            and <code>H5F_ACC_TRUNC</code> is not used, 
            <code>H5Fcreate</code> will return a failure because the file 
            already exists.  Note that this is correct behavior.
            <p>
            But if the library does not detect that the file is already 
            opened and <code>H5F_ACC_TRUNC</code> is used, 
            <code>H5Fcreate</code> will truncate the existing file
            and return a valid file identifier.
            Such a truncation of a currently-opened file will almost 
            certainly result in errors. 
            While unlikely, the HDF5 library may not be able to detect,
            and thus report, such errors.
            <p>
            Applications should avoid calling <code>H5Fcreate</code> 
            with an already opened file.

<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>const char *</em><code>name</code>
            <dd>IN: Name of the file to access.
        <dt><em>uintn</em> <code>flags</code>
            <dd>IN: File access flags.  Allowable values are:
                <ul><dl>
                    <dt><code>H5F_ACC_TRUNC</code>
                        <dd>Truncate file, if it already exists,  
                            erasing all data previously stored in the file.
                    <dt><code>H5F_ACC_EXCL</code>
                        <dd>Fail if file already exists.
                </dl></ul>
                <li><code>H5F_ACC_TRUNC</code> and <code>H5F_ACC_EXCL</code> 
                are mutually exclusive; use exactly one.
                <li>An additional flag, <code>H5F_ACC_DEBUG</code>, prints 
                debug information.  This flag is used only by HDF5 library 
                developers; <i>it is neither tested nor supported</i> 
                for use in applications.
        <dt><em>hid_t</em> <code>create_id</code>
            <dd>IN: File creation property list identifier, used when modifying
                default file meta-data.
                Use <code>H5P_DEFAULT</code> for default file creation properties.
        <dt><em>hid_t</em> <code>access_id</code>
            <dd>IN: File access property list identifier.
                If parallel file access is desired, this is a collective
                call according to the communicator stored in the
                <code>access_id</code>. 
                Use <code>H5P_DEFAULT</code> for default file access properties.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a file identifier if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fcreate_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fflush" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-Flush">H5Fflush</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Fflush</code>(<em>hid_t </em><code>object_id</code>,
        <em>H5F_scope_t</em> <code>scope</code>
        )
<dt><strong>Purpose:</strong>
        <dd>Flushes all buffers associated with a file to disk.
<dt><strong>Description:</strong>
        <dd><code>H5Fflush</code> causes all buffers associated with a
        file to be immediately flushed to disk without removing the
        data from the cache.  
        <p>
        <code>object_id</code> can be any object associated with the file, 
        including the file itself, a dataset, a group, an attribute, or 
        a named data type.
        <p>
        <code>scope</code> specifies whether the scope of the flushing 
        action is global or local.  Valid values are
        <center>
        <table border=0>
        <tr><td align=left valign=bottom><code>H5F_SCOPE_GLOBAL</code></td>
            <td>&nbsp;&nbsp;&nbsp;&nbsp;</td>
            <td align=left valign=bottom>Flushes the entire virtual file.</td></tr>
        <tr><td align=left valign=bottom><code>H5F_SCOPE_LOCAL</code></td>
            <td></td>
            <td align=left valign=bottom>Flushes only the specified file.</td></tr>
        </table>
        </center>       
<dt><strong>Note:</strong>
        <dd>HDF5 does not possess full control over buffering.
        <code>H5Fflush</code> flushes the internal HDF5 buffers then 
        asks the operating system (the OS) to flush the system buffers for the 
        open files.  After that, the OS is responsible for ensuring that
        the data is actually flushed to disk.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t </em><code>object_id</code>
            <dd>IN: Identifier of object used to identify the file.
        <dt><em>H5F_scope_t</em> <code>scope</code>
            <dd>IN: Specifies the scope of the flushing action.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fflush_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fget_access_plist" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-GetAccessPlist">H5Fget_access_plist</a>
<dt><strong>Signature:</strong>
    <dd><em>hid_t </em><code>H5Fget_access_plist</code>(<em>hid_t</em> <code>file_id</code>)
<dt><strong>Purpose:</strong>
        <dd>Returns a file access property list identifier.
<dt><strong>Description:</strong>
        <dd><code>H5Fget_access_plist</code> returns the 
            file access property list identifier of the specified file.
            <p>
            See "File Access Properties" in 
            <a href="RM_H5P.html">H5P: Property List Interface</a> 
            in this reference manual and 
            "File Access Property Lists" 
            in <a href="Files.html"><cite>Files</cite></a> in the 
            <cite>HDF5 User's Guide</cite> for 
            additional information and related functions.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>file_id</code>
            <dd>IN: Identifier of file to get access property list of
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a file access property list identifier if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fget_access_plist_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fget_create_plist" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-GetCreatePlist">H5Fget_create_plist</a>
<dt><strong>Signature:</strong>
    <dd><em>hid_t </em><code>H5Fget_create_plist</code>(<em>hid_t</em> <code>file_id</code>
        )
<dt><strong>Purpose:</strong>
        <dd>Returns a file creation property list identifier.
<dt><strong>Description:</strong>
        <dd><code>H5Fget_create_plist</code> returns a file creation 
            property list identifier identifying the creation properties 
            used to create this file.  This function is useful for 
            duplicating properties when creating another file.
            <p>
            See "File Creation Properties" in 
            <a href="RM_H5P.html">H5P: Property List Interface</a> 
            in this reference manual and 
            "File Creation Properties" 
            in <a href="Files.html"><cite>Files</cite></a> in the 
            <cite>HDF5 User's Guide</cite> for 
            additional information and related functions.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>file_id</code>
            <dd>IN: Identifier of the file to get creation property list of
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a file creation property list identifier if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fget_create_plist_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fget_obj_count" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-GetObjCount">H5Fget_obj_count</a>
<dt><strong>Signature:</strong>
    <dd><em>int </em><code>H5Fget_obj_count</code>(<em>hid_t</em> <code>file_id</code>,
	    <em>unsigned int</em> <code>types</code>
            )
<dt><strong>Purpose:</strong>
        <dd>Returns the number of open object identifiers for an open file.
<dt><strong>Description:</strong>
    <dd>Given the identifier of an open file, <code>file_id</code>, 
	and the desired object types, <code>types</code>,
	<code>H5Fget_obj_count</code> returns the number of 
        open object identifiers for the file.
        <p>
        To retrieve a count of open identifiers for open objects in 
	all HDF5 application files that are currently open, 
        pass the value <code>H5F_OBJ_ALL</code> in <code>file_id</code>.
        <p>
        The types of objects to be counted are specified 
	in <code>types</code> as follows:
	<center>
        <table width=90% border=0>
          <tr><td valign=top>
            <code>H5F_OBJ_FILE</code>
            </td><td valign=top>
            Files only
          </td></tr><tr><td valign=top>
            <code>H5F_OBJ_DATASET</code>
            </td><td valign=top>
            Datasets only
          </td></tr><tr><td valign=top>
            <code>H5F_OBJ_GROUP</code>
            </td><td valign=top>
            Groups only
          </td></tr><tr><td valign=top>
            <code>H5F_OBJ_DATATYPE&nbsp;&nbsp;</code>
            </td><td valign=top>
            Named datatypes only
          </td></tr><tr><td valign=top>
            <code>H5F_OBJ_ATTR&nbsp;&nbsp;</code>
            </td><td valign=top>
            Attributes only
          </td></tr><tr><td valign=top>
            <code>H5F_OBJ_ALL</code>
            </td><td valign=top>
            All of the above
	    <br>
	    (I.e., <code>H5F_OBJ_FILE</code> | <code>H5F_OBJ_DATASET</code> | 
	    <code>H5F_OBJ_GROUP</code> | <code>H5F_OBJ_DATATYPE</code> 
	    | <code>H5F_OBJ_ATTR</code> )
          </td></tr>
        </table>
	</center>
	Multiple object types can be combined with the 
	logical <code>OR</code> operator (<code>|</code>).
	For example, the expression <code>(H5F_OBJ_DATASET|H5F_OBJ_GROUP)</code> would call for 
	datasets and groups.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>file_id</code>
            <dd>IN: Identifier of a currently-open HDF5 file or 
	        <code>H5F_OBJ_ALL</code> for all currently-open HDF5 files. 
        <dt><em>unsigned int</em> <code>types</code>
            <dd>IN: Type of object for which identifiers are to be returned. 
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a the number of open objects if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fget_obj_count_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
     <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fget_obj_ids" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-GetObjIDs">H5Fget_obj_ids</a>
<dt><strong>Signature:</strong>
    <dd><em>int </em><code>H5Fget_obj_ids</code>(<em>hid_t</em> <code>file_id</code>,
            <em>unsigned int</em> <code>types</code>,
            <em>int</em> <code>max_objs</code>,
            <em>hid_t *</em><code>obj_id_list</code>
            )
<dt><strong>Purpose:</strong>
    <dd>Returns a list of open object identifiers.
<dt><strong>Description:</strong>
    <dd>Given the file identifier <code>file_id</code> and 
        the type of objects to be identified, <code>types</code>,
        <code>H5Fget_obj_ids</code> returns the list of identifiers 
        for all open HDF5 objects fitting the specified criteria. 
        <p>
        To retrieve identifiers for open objects in all HDF5 application 
        files that are currently open, pass the value 
        <code>H5F_OBJ_ALL</code> in <code>file_id</code>.
        <p>
        The types of object identifiers to be retrieved are specified 
	in <code>types</code> using the codes listed for the same 
	parameter in <a href="#File-GetObjCount"><code>H5Fget_obj_count</code></a>
        <p>
        To retrieve identifiers for all open objects, pass a negative value
        for the <code>max_objs</code>.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>file_id</code>
            <dd>IN: Identifier of a currently-open HDF5 file or 
	        <code>H5F_OBJ_ALL</code> for all currently-open HDF5 files. 
        <dt><em>unsigned int</em> <code>types</code>
            <dd>IN: Type of object for which identifiers are to be returned. 
        <dt><em>int</em> <code>max_objs</code>
            <dd>IN: Maximum number of object identifiers to place into <code>obj_id_list</code>.
        <dt><em>hid_t *</em><code>obj_id_list</code>
            <dd>OUT: Pointer to the returned list of open object identifiers. 
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns number of objects placed into <code>obj_id_list</code> if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fget_obj_ids_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fget_vfd_handle" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-GetVfdHandle">H5Fget_vfd_handle</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Fget_vfd_handle</code>(<em>hid_t</em> <code>file_id</code>,
                <em>hid_t</em> <code>fapl_id</code>,
                <em>void *</em><code>file_handle</code>
                )
<dt><strong>Purpose:</strong>
    <dd>Returns pointer to the file handle from the virtual file driver.
<dt><strong>Description:</strong>
    <dd>Given the file identifier <code>file_id</code> and 
    the file access property list <code>fapl_id</code>, 
    <code>H5Fget_vfd_handle</code> returns a pointer to the file handle 
    from the low-level file driver currently being used by the 
    HDF5 library for file I/O.
<dt><strong>Notes:</strong>
    <dd>Users are not supposed to modify any file through this file handle.
    <p>
    This file handle is dynamic and is valid only while the file remains
    open; it will be invalid if the file is closed and reopened or 
    opened during a subsequent session.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>file_id</code>
            <dd>IN: Identifier of the file to be queried.
        <dt><em>hid_t</em> <code>fapl_id</code>
            <dd>IN: File access property list  identifier.
	        For most drivers, the value will be <code>H5P_DEFAULT</code>. 
		For the <code>FAMILY</code> or <code>MULTI</code> drivers,
		this value should be defined through the property list
		functions: 
		<code>H5Pset_family_offset</code> for the <code>FAMILY</code> 
		driver and <code>H5Pset_multi_type</code> for the 
		<code>MULTI</code> driver.
        <dt><em>void *</em><code>file_handle</code>
            <dd>OUT: Pointer to the file handle being used by 
	        the low-level virtual file driver.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<!--
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fget_vfd_handle_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
-->    <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fis_hdf5" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-IsHDF5">H5Fis_hdf5</a>
<dt><strong>Signature:</strong>
    <dd><em>htri_t </em><code>H5Fis_hdf5</code>(<em>const char *</em><code>name</code>
        )
<dt><strong>Purpose:</strong>
        <dd>Determines whether a file is in the HDF5 format.
<dt><strong>Description:</strong>
        <dd><code>H5Fis_hdf5</code> determines whether a file is in 
            the HDF5 format.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>const char *</em><code>name</code>
            <dd>IN: File name to check format.
    </dl>
<dt><strong>Returns:</strong>
    <dd>When successful, returns a positive value, for <code>TRUE</code>,
        or <code>0</code> (zero), for <code>FALSE</code>.
        Otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fis_hdf5_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fmount" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-Mount">H5Fmount</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Fmount</code>(<em>hid_t</em> <code>loc_id</code>,
            <em>const char *</em><code>name</code>,
            <em>hid_t</em> <code>child_id</code>,
            <em>hid_t</em> <code>plist_id</code>
        )
<dt><strong>Purpose:</strong>
        <dd>Mounts a file.
<dt><strong>Description:</strong>
        <dd><code>H5Fmount</code> mounts the file specified by 
            <code>child_id</code> onto the group specified by 
            <code>loc_id</code> and <code>name</code> using 
            the mount properties <code>plist_id</code>.
            <p>
            Note that <code>loc_id</code> is either a file or group identifier
            and <code>name</code> is relative to <code>loc_id</code>.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>loc_id</code>
            <dd>IN: Identifier for of file or group in 
                which <code>name</code> is defined.
        <dt><em>const char *</em><code>name</code>
            <dd>IN: Name of the group onto which the 
                file specified by <code>child_id</code> 
                is to be mounted.
        <dt><em>hid_t</em> <code>child_id</code>
            <dd>IN: Identifier of the file to be mounted.
        <dt><em>hid_t</em> <code>plist_id</code>
            <dd>IN: Identifier of the property list to be used.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fmount_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Fopen" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-Open">H5Fopen</a>
<dt><strong>Signature:</strong>
    <dd><em>hid_t </em><code>H5Fopen</code>(<em>const char *</em><code>name</code>,
            <em>unsigned</em> <code>flags</code>,
            <em>hid_t</em> <code>access_id</code>
        )
<dt><strong>Purpose:</strong>
        <dd>Opens an existing file.
<dt><strong>Description:</strong>
        <dd><code>H5Fopen</code> opens an existing file and is the primary 
            function for accessing existing HDF5 files.  
            <p>
            The parameter <code>access_id</code> is a file access property
            list identifier or <code>H5P_DEFAULT</code> if the 
            default I/O access parameters are to be used  
            <p>
            The <code>flags</code> argument determines whether writing 
            to an existing file will be allowed.  
            The file is opened with read and write permission if 
            <code>flags</code> is set to <code>H5F_ACC_RDWR</code>.  
            All flags may be combined with the bit-wise OR operator (`|') 
            to change the behavior of the file open call.  
            More complex behaviors of file access are controlled 
            through the file-access property list.
            <p>
            The return value is a file identifier for the open file;
            this file identifier should be closed by calling 
            <code>H5Fclose</code> when it is no longer needed. 
            <p>

            <b>Special case -- Multiple opens:</b>
            <br>
            A file can often be opened with a new <code>H5Fopen</code> 
            call without closing an already-open identifier established 
            in a previous <code>H5Fopen</code> or <code>H5Fcreate</code> 
            call.  Each such <code>H5Fopen</code> call will return a 
            unique identifier and the file can be accessed through any 
            of these identifiers as long as the identifier remains valid.
            In such multiply-opened cases, all the open calls should 
            use the same <code>flags</code> argument. 
            <p>
            In some cases, such as files on a local Unix file system, 
            the HDF5 library can detect that a file is multiply opened and 
            will maintain coherent access among the file identifiers.
            <p>
            But in many other cases, such as parallel file systems or
            networked file systems, it is not always possible to detect 
            multiple opens of the same physical file.  
            In such cases, HDF5 will treat the file identifiers 
            as though they are accessing different files and
            will be unable to maintain coherent access.
            Errors are likely to result in these cases.
            While unlikely, the HDF5 library may not be able to detect,
            and thus report, such errors.
            <p>
            It is generally recommended that applications avoid 
            multiple opens of the same file.

<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>const char *</em><code>name</code>
            <dd>IN: Name of the file to access.
        <dt><em>unsigned</em> <code>flags</code>
            <dd>IN: File access flags.  Allowable values are:
                <ul><dl>
                    <dt><code>H5F_ACC_RDWR</code>
                        <dd>Allow read and write access to file.
                    <dt><code>H5F_ACC_RDONLY</code>
                        <dd>Allow read-only access to file.
                </dl>
                <li><code>H5F_ACC_RDWR</code> and <code>H5F_ACC_RDONLY</code> 
                are mutually exclusive; use exactly one.
                <li>An additional flag, <code>H5F_ACC_DEBUG</code>, prints 
                debug information.  This flag is used only by HDF5 library 
                developers; it is neither tested nor supported
                for use in applications.
                </ul>
        <dt><em>hid_t</em> <code>access_id</code>
            <dd>IN: Identifier for the file access properties list.
                If parallel file access is desired, this is a collective
                call according to the communicator stored in the
                <code>access_id</code>. 
                Use <code>H5P_DEFAULT</code> for default file access properties.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a file identifier if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5fopen_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Freopen" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-Reopen">H5Freopen</a>
<dt><strong>Signature:</strong>
    <dd><em>hid_t </em><code>H5Freopen</code>(<em>hid_t</em> <code>file_id</code>
        )
<dt><strong>Purpose:</strong>
        <dd>Returns a new identifier for a previously-opened HDF5 file.
<dt><strong>Description:</strong>
        <dd><code>H5Freopen</code> returns a new file identifier for an
            already-open HDF5 file, as specified by <code>file_id</code>.  
            Both identifiers share caches and other information.  
            The only difference between the identifiers is that the 
            new identifier is not mounted anywhere and no files are 
            mounted on it.
            <p>
            Note that there is no circumstance under which 
            <code>H5Freopen</code> can actually open a closed file; 
            the file  must already be open and have an active 
            <code>file_id</code>.  E.g., one cannot close a file with 
            <code> H5Fclose&nbsp;(file_id) </code> then use 
            <code> H5Freopen&nbsp;(file_id) </code> to reopen it.
            <p>
            The new file identifier should be closed by calling
            <code>H5Fclose</code> when it is no longer needed.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>file_id</code>
            <dd>IN: Identifier of a file for which an additional identifier 
                is required.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a new file identifier if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5freopen_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
        <img src="Graphics/Java.gif"> 
        <img src="Graphics/C++.gif">
        -->
</dl>

<!-- NEW PAGE -->
<!-- HEADER RIGHT "H5Funmount" -->
<hr>
<dl>
<dt><strong>Name:</strong> <a name="File-Unmount">H5Funmount</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Funmount</code>(<em>hid_t</em> <code>loc_id</code>,
            <em>const char *</em><code>name</code>
        )
<dt><strong>Purpose:</strong>
        <dd>Unmounts a file.
<dt><strong>Description:</strong>
        <dd>Given a mount point, <code>H5Funmount</code> 
            dissassociates the mount point's file
            from the file mounted there.  This function
            does  not close either file.
            <p> 
            The mount point can be either the group in the
            parent or the root group of the mounted file 
            (both groups have the same name).  If the mount 
            point was opened before the mount then it is the 
            group in the parent; if it was opened after the 
            mount then it is the root group of the child.
            <p>
            Note that <code>loc_id</code> is either a file or group identifier
            and <code>name</code> is relative to <code>loc_id</code>.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>loc_id</code>
            <dd>IN: File or group identifier for the location at which
                the specified file is to be unmounted.
        <dt><em>const char *</em><code>name</code>
            <dd>IN: Name of the mount point.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a non-negative value if successful;
        otherwise returns a negative value.
<dt><strong>Non-C API(s):</strong>
    <dd><a href="fortran/h5f_FORTRAN.html#h5funmount_f" 
        target="FortranWin"><img src="Graphics/FORTRAN.gif" border=0></a>
        <!--
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