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HDF5/H5T Draft API Specification
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<h1>H5T: Datatype Interface</h1>
</center>

<h2>Datatype Object API Functions</h2>

These functions create and manipulate the datatype which describes elements
of a dataset.

<table border=0>
<tr><td valign=top>
<i>General Datatype Operations</i>
    <li><a href="#Datatype-Create">H5Tcreate</a>
    <li><a href="#Datatype-Open">H5Topen</a>
    <li><a href="#Datatype-Commit">H5Tcommit</a>
    <li><a href="#Datatype-Committed">H5Tcommitted</a>
    <li><a href="#Datatype-Copy">H5Tcopy</a>
    <li><a href="#Datatype-Equal">H5Tequal</a>
    <li><a href="#Datatype-Lock">H5Tlock</a>
    <li><a href="#Datatype-Close">H5Tclose</a>
<p>
<i>Atomic Datatype Properties</i>
    <li><a href="#Datatype-GetClass">H5Tget_class</a>
    <li><a href="#Datatype-GetSize">H5Tget_size</a>
    <li><a href="#Datatype-SetSize">H5Tset_size</a>
    <li><a href="#Datatype-GetOrder">H5Tget_order</a>
    <li><a href="#Datatype-SetOrder">H5Tset_order</a>
    <li><a href="#Datatype-GetPrecision">H5Tget_precision</a>
    <li><a href="#Datatype-SetPrecision">H5Tset_precision</a>
    <li><a href="#Datatype-GetOffset">H5Tget_offset</a>
    <li><a href="#Datatype-SetOffset">H5Tset_offset</a>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
    <li><a href="#Datatype-GetPad">H5Tget_pad</a>
    <li><a href="#Datatype-SetPad">H5Tset_pad</a>
    <li><a href="#Datatype-GetSign">H5Tget_sign</a>
    <li><a href="#Datatype-SetSign">H5Tset_sign</a>
    <li><a href="#Datatype-GetFields">H5Tget_fields</a>
    <li><a href="#Datatype-SetFields">H5Tset_fields</a>
    <li><a href="#Datatype-GetEbias">H5Tget_ebias</a>
    <li><a href="#Datatype-SetEbias">H5Tset_ebias</a>
    <li><a href="#Datatype-GetNorm">H5Tget_norm</a>
    <li><a href="#Datatype-SetNorm">H5Tset_norm</a>
    <li><a href="#Datatype-GetInpad">H5Tget_inpad</a>
    <li><a href="#Datatype-SetInpad">H5Tset_inpad</a>
    <li><a href="#Datatype-GetCset">H5Tget_cset</a>
    <li><a href="#Datatype-SetCset">H5Tset_cset</a>
    <li><a href="#Datatype-GetStrpad">H5Tget_strpad</a>
    <li><a href="#Datatype-SetStrpad">H5Tset_strpad</a>
<p>
<i>Properties of Compound Types</i>
    <li><a href="#Datatype-GetClass">H5Tget_class</a>
    <li><a href="#Datatype-GetSize">H5Tget_size</a>
</td><td>&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;&nbsp;</td><td valign=top>
    <li><a href="#Datatype-GetNmembers">H5Tget_nmembers</a>
    <li><a href="#Datatype-GetMemberName">H5Tget_member_name</a>
    <li><a href="#Datatype-GetMemberOffset">H5Tget_member_offset</a>
    <li><a href="#Datatype-GetMemberDims">H5Tget_member_dims</a>
    <li><a href="#Datatype-GetMemberType">H5Tget_member_type</a>
    <li><a href="#Datatype-Insert">H5Tinsert</a>
    <li><a href="#Datatype-Pack">H5Tpack</a>
    <li><a href="#Datatype-InsertArray">H5Tinsert_array</a>
<p>
<i>Conversion Functions</i>
    <li><a href="#Datatype-Convert">H5Tconvert</a>
    <li><a href="#Datatype-Find">H5Tfind</a>
    <li><a href="#Datatype-SetOverflow">H5Tset_overflow</a>
    <li><a href="#Datatype-GetOverflow">H5Tget_overflow</a>
    <li><a href="#Datatype-RegisterHard">H5Tregister_hard</a>
    <li><a href="#Datatype-RegisterSoft">H5Tregister_soft</a>
    <li><a href="#Datatype-Unregister">H5Tunregister</a>
</td></tr>
</table>

<p>
The Datatype interface, H5T, provides a mechanism to describe the
      storage format of individual data points of a data set and is
      hopefully designed in such a way as to allow new features to be
      easily added without disrupting applications that use the data
      type interface.  A dataset (the H5D interface) is composed of a
      collection or raw data points of homogeneous type organized
      according to the data space (the H5S interface).

<p>
A datatype is a collection of datatype properties, all of
      which can be stored on disk, and which when taken as a whole,
      provide complete information for data conversion to or from that
      datatype.  The interface provides functions to set and query
      properties of a datatype.
      
<p>
A <em>data point</em> is an instance of a <em>datatype</em>,
      which is an instance of a <em>type class</em>.  We have defined
      a set of type classes and properties which can be extended at a
      later time.  The atomic type classes are those which describe
      types which cannot be decomposed at the datatype interface
      level; all other classes are compound.

<p>
See <a href="Datatypes.html"><cite>The Datatype Interface (H5T)</cite></a>
in the <cite>HDF5 User's Guide</cite> for further information, including a complete list of all supported datatypes.


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Open">H5Topen</a>
<dt><strong>Signature:</strong>
    <dd><em>hid_t</em><code>H5Topen</code>(<em>hid_t</em> <code>loc_id</code>,
        <em>const char *</em> <code>name</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Opens a named datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Topen</code> opens a named datatype at the location
        specified by <code>loc_id</code> and returns an identifier 
        for the datatype.  <code>loc_id</code> is either a file or 
        group identifier.  The identifier should eventually be closed 
        by calling <code>H5Tclose()</code> to release resources.    
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>loc_id</code>
            <dd>A file, group, or datatype identifier.
        <dt><em>const char *</em> <code>name</code>
            <dd>A datatype name.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a named datatype identifier if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Commit">H5Tcommit</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em><code>H5Tcommit</code>(<em>hid_t</em> <code>loc_id</code>,
        <em>const char *</em> <code>name</code>,
        <em>hid_t</em> <code>type</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Commits a transient datatype to a file, creating a new named datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tcommit</code> commits a transient datatype 
        (not immutable) to a file, turned it into a named datatype.  
        The <code>loc_id</code> is either a file or group identifier  
        which, when combined with <code>name</code>, refers to a new 
        named datatype.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>loc_id</code>
            <dd>A file or group identifier.
        <dt><em>const char *</em> <code>name</code>
            <dd>A datatype name.
        <dt><em>hid_t</em> <code>type</code>
            <dd>A datatype identifier.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Committed">H5Tcommitted</a>
<dt><strong>Signature:</strong>
    <dd><em>hbool_t</em><code>H5Tcommitted</code>(<em>hid_t</em> <code>type</code>)
<dt><strong>Purpose:</strong>
    <dd>Determines whether a datatype is a named type or a transient type.  
<dt><strong>Description:</strong>
    <dd><code>H5Tcommitted</code> queries a type to determine whether 
        the type specified by the <code>type</code> identifier 
        is a named type or a transient type.  If this function returns 
        a positive value, then the type is named (that is, it has been 
        committed, perhaps by some other application).  Datasets which
        return committed datatypes with <code>H5Dget_type()</code> are 
        able to share the datatype with other datasets in the same file.
<dt><strong>Parameters:</strong>
    <dl>
        <dt>hid_t</em> <code>type</code>
            <dd>Datatype identifier.
    </dl>
<dt><strong>Returns:</strong>
    <dd>The successful return values are TRUE if committed, else FALSE.
        Otherwise returns FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-InsertArray">H5Tinsert_array</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em><code>H5Tinsert_array</code>(<em>hid_t</em> <code>parent_id</code>,
        <em>const char *</em><code>name</code>,
        <em>size_t</em> <code>offset</code>,
        <em>int</em> <code>ndims</code>,
        <em>const size_t *</em><code>dim</code>,
        <em>const int *</em><code>perm</code>,
        <em>hid_t</em> <code>member_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Adds an array member to a compound datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tinsert_array</code> adds a new member to the 
        compound datatype <code>parent_id</code>.  
        The member is an array with <code>ndims</code> dimensionality 
        and the size of the array is </em><code>dim</code>.
        The new member's name, <code>name</code>, must be unique 
        within the compound datatype.  
        The <code>offset</code> argument defines the start of the 
        member in an instance of the compound datatype and
        <code>member_id</code> is the type identifier of the new member.  
        The total member size should be relatively small.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>parent_id</code>
            <dd>Identifier of the parent compound datatype.
        <dt><em>const char *</em><code>name</code>
            <dd>Name of new member.
        <dt><em>size_t</em> <code>offset</code>
            <dd>Offset to start of new member within compound datatype.
        <dt><em>int</em> <code>ndims</code>
            <dd>Dimensionality of new member.
        <dt><em>const size_t *</em><code>dim</code>
            <dd>Size of new member array.
        <dt><em>const int *</em><code>perm</code>
            <dd>Pointer to buffer to store the permutation vector of 
                the field.
        <dt><em>hid_t</em> <code>member_id</code>
            <dd>Identifier of the datatype of the new member.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Find">H5Tfind</a>
<dt><strong>Signature:</strong>
    <dd><em>H5T_conv_t</em> <code>H5Tfind</code>(<em>hid_t</em> <code>src_id</code>,
        <em>hid_t</em> <code>dst_id</code>,
        <em>H5T_cdata_t **</em><code>pcdata</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Finds a conversion function.
<dt><strong>Description:</strong>
    <dd><code>H5Tfind</code> finds a conversion function that can 
        handle a conversion from type <code>src_id</code> to type 
        <code>dst_id</code>.
        The <code>pcdata</code> argument is a pointer to a pointer 
        to type conversion data which was created and initialized 
        by the soft type conversion function of this path when the 
        conversion function was installed on the path.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>src_id</code>
            <dd>Identifier for the source datatype.
        <dt><em>hid_t</em> <code>dst_id</code>
            <dd>Identifier for the destination datatype.
        <dt><em>H5T_cdata_t **</em><code>pcdata</code>
            <dd>Pointer to type conversion data.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a pointer to a suitable conversion function if successful.
        Otherwise returns NULL.
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Convert">H5Tconvert</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Tconvert</code>(<em>hid_t</em> <code>src_id</code>,
        <em>hid_t</em> <code>dst_id</code>,
        <em>size_t</em> <code>nelmts</code>,
        <em>void *</em><code>buf</code>,
        <em>void *</em><code>background</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Converts data from between specified datatypes.
<dt><strong>Description:</strong>
    <dd><code>H5Tconvert</code> converts <code>nelmts</code> elements 
        from the type specified by the <code>src_id</code> identifier 
        to type <code>dst_id</code>.  
        The source elements are packed in <code>buf</code> and on return 
        the destination will be packed in <code>buf</code>.  
        That is, the conversion is performed in place.  
        The optional background buffer is an array of <code>nelmts</code> 
        values of destination type which are merged with the converted 
        values to fill in cracks (for instance, <code>background</code> 
        might be an array of structs with the <code>a</code> and 
        <code>b</code> fields already initialized and the conversion  
        of <code>buf</code> supplies the <code>c</code> and <code>d</code> 
        field values).
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>src_id</code>
            <dd>Identifier for the source datatype.
        <dt><em>hid_t</em> <code>dst_id</code>
            <dd>Identifier for the destination datatype.
        <dt><em>size_t</em> <code>nelmts</code>
            <dd>Size of array <code>buf</code>.
        <dt><em>void *</em><code>buf</code>
            <dd>Array containing pre- and post-conversion values.
        <dt><em>void *</em><code>background</code>
            <dd>Optional background buffer.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetOverflow">H5Tset_overflow</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Tset_overflow</code>(<em>H5T_overflow_t</em> <code>func</code>)
<dt><strong>Purpose:</strong>
    <dd>Sets the overflow handler to a specified function. 
<dt><strong>Description:</strong>
    <dd><code>H5Tset_overflow</code> sets the overflow handler 
        to be the function specified by <code>func</code>.
        <code>func</code> will be called for all datatype conversions that 
        result in an overflow.  
        <p>
        See the definition of <code>H5T_overflow_t</code> in 
        <code>H5Tpublic.h</code> for documentation  
        of arguments and return values.  
        The prototype for <code>H5T_overflow_t</code> is as follows:<br>
              <code>herr_t (*H5T_overflow_t)(hid_t src_id, hid_t dst_id,
                                 void *src_buf, void *dst_buf);
              </code>
        <p>
        The NULL pointer may be passed to remove the overflow handler.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>H5T_overflow_t</em> <code>func</code>
            <dd>Overflow function.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetOverflow">H5Tget_overflow</a>
<dt><strong>Signature:</strong>


H5Tget_overflow ()
    <dd><em>H5T_overflow_t</em> <code>H5Tget_overflow</code>(<code>void</code>)
<dt><strong>Purpose:</strong>
    <dd>Returns a pointer to the current global overflow function.
<dt><strong>Description:</strong>
    <dd><code>H5Tset_overflow</code> returns a pointer 
        to the current global overflow function.
        This is an application-defined function that is called whenever a 
        datatype conversion causes an overflow. 
<dt><strong>Parameters:</strong>
    <dl>
        <dt>None.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a pointer to an application-defined function if successful.
        Otherwise returns NULL; this can happen if no overflow handling
        function is registered.  
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Create">H5Tcreate</a>
<dt><strong>Signature:</strong>
    <dd><em>hid_t </em><code>H5Tcreate</code>(<em>H5T_class_t </em><code>class</code>,
        <em>size_t</em><code>size</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Creates a new dataype.
<dt><strong>Description:</strong>
    <dd><code>H5Tcreate</code> creates a new dataype of the specified 
        class with the specified number of bytes.  
        Currently, only the <code>H5T_COMPOUND</code> datatype class is 
        supported with this function.  Use <code>H5Tcopy</code>
        to create integer or floating-point datatypes.  
        The datatype identifier returned from this function should be 
        released with <code>H5Tclose</code> or resource leaks will result.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>H5T_class_t</em> <code>class</code>
            <dd>Class of datatype to create.
        <dt><em>size_t</em> <code>size</code>
            <dd>The number of bytes in the datatype to create.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns datatype identifier if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Copy">H5Tcopy</a>
<dt><strong>Signature:</strong>
    <dd><em>hid_t </em><code>H5Tcopy</code>(<em>hid_t </em><code>type_id</code>)
<dt><strong>Purpose:</strong>
    <dd>Copies an existing datatype.  
<dt><strong>Description:</strong>
    <dd><code>H5Tcopy</code> copies an existing datatype.  
        The returned type is always transient and unlocked.  
        <p>
        The <code>type_id</code> argument can be either a datatype
        identifier, a predefined datatype (defined in 
        <code>H5Tpublic.h</code>), or a dataset identifier.
        If <code>type_id</code> is a dataset identifier instead of a 
        datatype identifier, then this function returns a transient, 
        modifiable datatype which is a copy of the dataset's datatype.
        <p>
        The datatype identifier returned should be released with 
        <code>H5Tclose</code> or resource leaks will occur.  
<!--
        <p>
        Native datatypes supported by the library are:
        <ul> <dl>
            <dt>H5T_NATIVE_CHAR
                <dd> Native character type, declare dataset array as 'char'
            <dt>H5T_NATIVE_UCHAR
                <dd> Native unsigned character type, declare dataset array as 'unsigned char'
            <dt>H5T_NATIVE_SHORT
                <dd> Native short type, declare dataset array as 'short'
            <dt>H5T_NATIVE_USHORT
                <dd> Native unsigned short type, declare dataset array as 'unsigned short'
            <dt>H5T_NATIVE_INT
                <dd> Native int type, declare dataset array as 'int'
            <dt>H5T_NATIVE_UINT
                <dd> Native unsigned int type, declare dataset array as 'unsigned int'
            <dt>H5T_NATIVE_LONG
                <dd> Native long type, declare dataset array as 'unsigned long'
            <dt>H5T_NATIVE_ULONG
                <dd> Native unsigned long type, declare dataset array as 'unsigned long'
            <dt>H5T_NATIVE_LLONG
                <dd> Native long long type, declare dataset array as 'unsigned long long'
            <dt>H5T_NATIVE_ULLONG
                <dd> Native unsigned long long type, declare dataset array as 'unsigned long long'
            <dt>H5T_NATIVE_INT8
                <dd> Native signed 8-bit type, declare dataset array as 'int8'
            <dt>H5T_NATIVE_UINT8
                <dd> Native unsigned 8-bit type, declare dataset array as 'uint8'
            <dt>H5T_NATIVE_INT16
                <dd> Native signed 16-bit type, declare dataset array as 'int16'
            <dt>H5T_NATIVE_UINT16
                <dd> Native unsigned 16-bit type, declare dataset array as 'uint16'
            <dt>H5T_NATIVE_INT32
                <dd> Native signed 32-bit type, declare dataset array as 'int32'
            <dt>H5T_NATIVE_UINT32
                <dd> Native unsigned 32-bit type, declare dataset array as 'uint32'
            <dt>H5T_NATIVE_INT64
                <dd> Native signed 64-bit type, declare dataset array as 'uint64'
            <dt>H5T_NATIVE_UINT64
                <dd> Native unsigned 64-bit type, declare dataset array as 'uint64'
            <dt>H5T_NATIVE_FLOAT
                <dd> Native single-precision float type, declare dataset array as 'float'
            <dt>H5T_NATIVE_DOUBLE
                <dd> Native double-precision float type, declare dataset array as 'double'
            <dt>H5T_NATIVE_HSIZE
                <dd> Native size_t type, declare dataset array as 'hsize_t'
            <dt>H5T_NATIVE_HSSIZE
                <dd> Native signed size_t type, declare dataset array as 'hssize_t'
            <dt>H5T_NATIVE_HERR
                <dd> Native error type, declare dataset array as 'herr_t'
            <dt>H5T_NATIVE_HBOOL
                <dd> Native boolean type, declare dataset array as 'hbool_t'
        </dl> </ul>
-->
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to copy.  Can be a datatype
                identifier, a predefined datatype (defined in 
                <code>H5Tpublic.h</code>), or a dataset identifier.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a datatype identifier if successful;
        otherwise FAIL (-1)
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Equal">H5Tequal</a>
<dt><strong>Signature:</strong>
    <dd><em>hbool_t </em><code>H5Tequal</code>(<em>hid_t </em><code>type_id1</code>,
        <em>hid_t</em><code>type_id2</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Determines whether two datatype identifiers refer to the same datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tequal</code> determines whether two datatype identifiers 
        refer to the same datatype.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id1</code>
            <dd>Identifier of datatype to compare.
        <dt><em>hid_t</em> <code>type_id2</code>
            <dd>Identifier of datatype to compare.
    </dl>
<dt><strong>Returns:</strong>
    <dd>When successful, returns TRUE if the datatype identifiers
        refer to the same datatype, else FALSE.
        Otherwise returns FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Lock">H5Tlock</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tlock</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Locks a datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tlock</code> locks the datatype specified by the 
        <code>type_id</code> identifier, making it read-only and 
        non-destrucible.  This is normally done by the library for 
        predefined datatypes so the application does not 
        inadvertently change or delete a predefined type.  
        Once a datatype is locked it can never be unlocked.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to lock.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetClass">H5Tget_class</a>
<dt><strong>Signature:</strong>
    <dd><em>H5T_class_t </em><code>H5Tget_class</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Returns the datatype class identifier.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_class</code> returns the datatype class identifier.
        <p>
        Valid class identifiers, as defined in <code>H5Tpublic.h</code>, are:
        <ul><li><code>H5T_INTEGER</code> (<code>0</code>)
            <li><code>H5T_FLOAT</code> (<code>1</code>)
            <li><code>H5T_TIME</code> (<code>2</code>)
            <li><code>H5T_STRING</code> (<code>3</code>)
            <li><code>H5T_BITFIELD</code> (<code>4</code>)
            <li><code>H5T_OPAQUE</code> (<code>5</code>)
            <li><code>H5T_COMPOUND</code> (<code>6</code>)
        </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns datatype class identifier if successful;
        otherwise H5T_NO_CLASS (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetSize">H5Tget_size</a>
<dt><strong>Signature:</strong>
    <dd><em>size_t </em><code>H5Tget_size</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Returns the size of a datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_size</code> returns the size of a datatype in bytes.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns the size of the datatype in bytes if successful;
        otherwise 0.
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetSize">H5Tset_size</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_size</code>(<em>hid_t </em><code>type_id</code>,
        <em>size_t</em><code>size</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets the total size for an atomic datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tset_size</code> sets the total size in bytes, 
        <code>size</code>, for an atomic datatype (this operation
        is not permitted on compound datatypes).  If the size is
         decreased so that the significant bits of the datatype extend beyond
         the edge of the new size, then the `offset' property is decreased
         toward zero.  If the `offset' becomes zero and the significant
         bits of the datatype still hang over the edge of the new size, then
         the number of significant bits is decreased.
         Adjusting the size of an H5T_STRING automatically sets the precision
         to 8*size.  All datatypes have a positive size.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to change size.
        <dt><em>size_t</em> <code>size</code>
            <dd>Size in bytes to modify datatype.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetOrder">H5Tget_order</a>
<dt><strong>Signature:</strong>
    <dd><em>H5T_order_t </em><code>H5Tget_order</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Returns the byte order of an atomic datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_order</code> returns the byte order of an 
        atomic datatype.
        <p>
        Possible return values are:
        <ul><dl>
            <dt><code>H5T_ORDER_LE</code> (<code>0</code>)
                <dd>Little endian byte ordering (default).
            <dt><code>H5T_ORDER_BE</code> (<code>1</code>)
                <dd>Big endian byte ordering.
            <dt><code>H5T_ORDER_VAX</code> (<code>2</code>)
                <dd>VAX mixed byte ordering (not currently supported).
        </dl></ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a byte order constant if successful;
        otherwise <code>H5T_ORDER_ERROR</code> (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetOrder">H5Tset_order</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_order</code>(<em>hid_t </em><code>type_id</code>,
        <em>H5T_order_t</em><code>order</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets the byte ordering of an atomic datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tset_order</code> sets the byte ordering of an atomic datatype.
        Byte orderings currently supported are:
        <ul> <dl>
            <dt>H5T_ORDER_LE (<code>0</code>)
                <dd> Little-endian byte ordering (default).
            <dt>H5T_ORDER_BE (<code>1</code>)
                <dd> Big-endian byte ordering.
            <dt>H5T_ORDER_VAX (<code>2</code>)
                <dd>VAX mixed byte ordering (not currently supported).
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to set.
        <dt><em>H5T_order_t</em> <code>order</code>
            <dd>Byte ordering constant.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetPrecision">H5Tget_precision</a>
<dt><strong>Signature:</strong>
    <dd><em>size_t </em><code>H5Tget_precision</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Returns the precision of an atomic datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_precision</code> returns the precision of an atomic datatype.  The
        precision is the number of significant bits which, unless padding is
        present, is 8 times larger than the value returned by H5Tget_size().
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns the number of significant bits if successful;
        otherwise 0.
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetPrecision">H5Tset_precision</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_precision</code>(<em>hid_t </em><code>type_id</code>,
        <em>size_t</em><code>precision</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets the precision of an atomic datatype.  
<dt><strong>Description:</strong>
    <dd><code>H5Tset_precision</code> sets the precision of an atomic datatype.  
        The precision is the number of significant bits which, unless padding 
        is present, is 8 times larger than the value returned by H5Tget_size().
        <P>If the precision is increased then the offset is decreased and then
            the size is increased to insure that significant bits do not "hang
            over" the edge of the datatype.
        <P>Changing the precision of an H5T_STRING automatically changes the
            size as well.  The precision must be a multiple of 8.
        <P>When decreasing the precision of a floating point type, set the
            locations and sizes of the sign, mantissa, and exponent fields
            first.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to set.
        <dt><em>size_t</em> <code>precision</code>
            <dd>Number of bits of precision for datatype.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetOffset">H5Tget_offset</a>
<dt><strong>Signature:</strong>
    <dd><em>size_t </em><code>H5Tget_offset</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves the bit offset of the first significant bit.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_offset</code> retrieves the bit offset of the first significant bit.
        The signficant bits of an atomic datum can be offset from the beginning
        of the memory for that datum by an amount of padding. The `offset'
        property specifies the number of bits of padding that appear to the
        "right of" the value.  That is, if we have a 32-bit datum with 16-bits
        of precision having the value 0x1122 then it will be layed out in
        memory as (from small byte address toward larger byte addresses):
        <br>
        <br>

      <table border align=center cellpadding=4 width="80%">
        <tr align=center>
          <th width="20%">Byte Position</th>
          <th width="20%">Big-Endian Offset=0</th>
          <th width="20%">Big-Endian Offset=16</th>
          <th width="20%">Little-Endian Offset=0</th>
          <th width="20%">Little-Endian Offset=16</th>
        </tr>  
        <tr align=center>
          <td>0:</td>
          <td>[ pad]</td>
          <td>[0x11]</td>
          <td>[0x22]</td>
          <td>[ pad]</td>
        </tr>
        <tr align=center>
          <td>1:</td>
          <td>[ pad]</td>
          <td>[0x22]</td>
          <td>[0x11]</td>
          <td>[ pad]</td>
        </tr>
        <tr align=center>
          <td>2:</td>
          <td>[0x11]</td>
          <td>[ pad]</td>
          <td>[ pad]</td>
          <td>[0x22]</td>
        </tr>
        <tr align=center>
          <td>3:</td>
          <td>[0x22]</td>
          <td>[ pad]</td>
          <td>[ pad]</td>
          <td>[0x11]</td>
        </tr>
      </table>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a positive offset value if successful;
        otherwise 0.
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetOffset">H5Tset_offset</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_offset</code>(<em>hid_t </em><code>type_id</code>,
        <em>size_t</em> <code>offset</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets the bit offset of the first significant bit.
<dt><strong>Description:</strong>
    <dd><code>H5Tset_offset</code> sets the bit offset of the first significant bit.  The
        signficant bits of an atomic datum can be offset from the beginning of
        the memory for that datum by an amount of padding. The `offset'
        property specifies the number of bits of padding that appear to the
        "right of" the value.  That is, if we have a 32-bit datum with 16-bits
        of precision having the value 0x1122 then it will be layed out in
        memory as (from small byte address toward larger byte addresses):
        <br>
        <br>

      <table border align=center cellpadding=4 width="80%">
        <tr align=center>
          <th width="20%">Byte Position</th>
          <th width="20%">Big-Endian Offset=0</th>
          <th width="20%">Big-Endian Offset=16</th>
          <th width="20%">Little-Endian Offset=0</th>
          <th width="20%">Little-Endian Offset=16</th>
        </tr>  
        <tr align=center>
          <td>0:</td>
          <td>[ pad]</td>
          <td>[0x11]</td>
          <td>[0x22]</td>
          <td>[ pad]</td>
        </tr>
        <tr align=center>
          <td>1:</td>
          <td>[ pad]</td>
          <td>[0x22]</td>
          <td>[0x11]</td>
          <td>[ pad]</td>
        </tr>
        <tr align=center>
          <td>2:</td>
          <td>[0x11]</td>
          <td>[ pad]</td>
          <td>[ pad]</td>
          <td>[0x22]</td>
        </tr>
        <tr align=center>
          <td>3:</td>
          <td>[0x22]</td>
          <td>[ pad]</td>
          <td>[ pad]</td>
          <td>[0x11]</td>
        </tr>
      </table>

<P>If the offset is incremented then the total size is
incremented also if necessary to prevent significant bits of
the value from hanging over the edge of the datatype.

<P>The offset of an H5T_STRING cannot be set to anything but
zero.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to set.
        <dt><em>size_t</em> <code>offset</code>
            <dd>Offset of first significant bit.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetPad">H5Tget_pad</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tget_pad</code>(<em>hid_t </em><code>type_id</code>,
        <em>H5T_pad_t *</em> <code>lsb</code>,
        <em>H5T_pad_t *</em> <code>msb</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves the padding type of the least and most-significant bit padding.  
<dt><strong>Description:</strong>
    <dd><code>H5Tget_pad</code> retrieves the padding type of the least and most-significant
        bit padding.  Valid types are:
        <ul> <dl>
            <dt>H5T_PAD_ZERO (<code>0</code>)
               <dd>Set background to zeros.
            <dt>H5T_PAD_ONE (<code>1</code>)
               <dd>Set background to ones.
            <dt>H5T_PAD_BACKGROUND (<code>2</code>)
               <dd>Leave background alone.
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>IN: Identifier of datatype to query.
        <dt><em>H5T_pad_t *</em> <code>lsb</code>
            <dd>OUT: Pointer to location to return least-significant 
                bit padding type.
        <dt><em>H5T_pad_t *</em> <code>msb</code>
            <dd>OUT: Pointer to location to return most-significant 
                bit padding type.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetPad">H5Tset_pad</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_pad</code>(<em>hid_t </em><code>type_id</code>,
        <em>H5T_pad_t</em> <code>lsb</code>,
        <em>H5T_pad_t</em> <code>msb</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets the least and most-significant bits padding types.
<dt><strong>Description:</strong>
    <dd><code>H5Tset_pad</code> sets the least and most-significant bits padding types.
        <ul> <dl>
            <dt>H5T_PAD_ZERO (<code>0</code>)
               <dd>Set background to zeros.
            <dt>H5T_PAD_ONE (<code>1</code>)
               <dd>Set background to ones.
            <dt>H5T_PAD_BACKGROUND (<code>2</code>)
               <dd>Leave background alone.
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to set.
        <dt><em>H5T_pad_t</em> <code>lsb</code>
            <dd>Padding type for least-significant bits.
        <dt><em>H5T_pad_t</em> <code>msb</code>
            <dd>Padding type for most-significant bits.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetSign">H5Tget_sign</a>
<dt><strong>Signature:</strong>
    <dd><em>H5T_sign_t </em><code>H5Tget_sign</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves the sign type for an integer type.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_sign</code> retrieves the sign type for an integer type.
        Valid types are:
        <ul> <dl>
            <dt>H5T_SGN_NONE (<code>0</code>)
               <dd>Unsigned integer type.
            <dt>H5T_SGN_2 (<code>1</code>)
               <dd>Two's complement signed integer type.
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a valid sign type if successful;
        otherwise <code>H5T_SGN_ERROR</code> (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetSign">H5Tset_sign</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_sign</code>(<em>hid_t </em><code>type_id</code>,
        <em>H5T_sign_t</em> <code>sign</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets the sign proprety for an integer type.
<dt><strong>Description:</strong>
    <dd><code>H5Tset_sign</code> sets the sign proprety for an integer type.
        <ul> <dl>
            <dt>H5T_SGN_NONE (<code>0</code>)
               <dd>Unsigned integer type.
            <dt>H5T_SGN_2 (<code>1</code>)
               <dd>Two's complement signed integer type.
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to set.
        <dt><em>H5T_sign_t</em> <code>sign</code>
            <dd>Sign type.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetFields">H5Tget_fields</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tget_fields</code>(<em>hid_t </em><code>type_id</code>,
        <em>size_t *</em> <code>epos</code>,
        <em>size_t *</em> <code>esize</code>,
        <em>size_t *</em> <code>mpos</code>,
        <em>size_t *</em> <code>msize</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves floating point datatype bit field information.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_fields</code> retrieves information about the locations of the various
        bit fields of a floating point datatype.  The field positions are bit
        positions in the significant region of the datatype.  Bits are
        numbered with the least significant bit number zero.
        Any (or even all) of the arguments can be null pointers.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>IN: Identifier of datatype to query.
        <dt><em>size_t *</em> <code>epos</code>
            <dd>OUT: Pointer to location to return exponent bit-position.
        <dt><em>size_t *</em> <code>esize</code>
            <dd>OUT: Pointer to location to return size of exponent in bits.
        <dt><em>size_t *</em> <code>mpos</code>
            <dd>OUT: Pointer to location to return mantissa bit-position.
        <dt><em>size_t *</em> <code>msize</code>
            <dd>OUT: Pointer to location to return size of mantissa in bits.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetFields">H5Tset_fields</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_fields</code>(<em>hid_t </em><code>type_id</code>,
        <em>size_t</em> <code>epos</code>,
        <em>size_t</em> <code>esize</code>,
        <em>size_t</em> <code>mpos</code>,
        <em>size_t</em> <code>msize</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets locations and sizes of floating point bit fields.  
<dt><strong>Description:</strong>
    <dd><code>H5Tset_fields</code> sets the locations and sizes of the various floating
        point bit fields.  The field positions are bit positions in the
        significant region of the datatype.  Bits are numbered with the least
        significant bit number zero.
    
        <P>Fields are not allowed to extend beyond the number of bits of
        precision, nor are they allowed to overlap with one another.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to set.
        <dt><em>size_t</em> <code>epos</code>
            <dd>Exponent bit position.
        <dt><em>size_t</em> <code>esize</code>
            <dd>Size of exponent in bits.
        <dt><em>size_t</em> <code>mpos</code>
            <dd>Mantissa bit position.
        <dt><em>size_t</em> <code>msize</code>
            <dd>Size of mantissa in bits.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetEbias">H5Tget_ebias</a>
<dt><strong>Signature:</strong>
    <dd><em>size_t </em><code>H5Tget_ebias</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves the exponent bias of a floating-point type.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_ebias</code> retrieves the exponent bias of a floating-point type.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns the bias if successful;
        otherwise 0.
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetEbias">H5Tset_ebias</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_ebias</code>(<em>hid_t </em><code>type_id</code>,
        <em>size_t</em> <code>ebias</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets the exponent bias of a floating-point type.
<dt><strong>Description:</strong>
    <dd><code>H5Tset_ebias</code> sets the exponent bias of a floating-point type.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to set.
        <dt><em>size_t</em> <code>ebias</code>
            <dd>Exponent bias value.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetNorm">H5Tget_norm</a>
<dt><strong>Signature:</strong>
    <dd><em>H5T_norm_t </em><code>H5Tget_norm</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves mantissa normalization of a floating-point datatype.  
<dt><strong>Description:</strong>
    <dd><code>H5Tget_norm</code> retrieves the mantissa normalization of 
        a floating-point datatype.  Valid normalization types are:
        <ul> <dl>
            <dt>H5T_NORM_IMPLIED (<code>0</code>)
                <dd>MSB of mantissa is not stored, always 1
            <dt>H5T_NORM_MSBSET (<code>1</code>)
                <dd>MSB of mantissa is always 1
            <dt>H5T_NORM_NONE (<code>2</code>)
                <dd>Mantissa is not normalized
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a valid normalization type if successful;
        otherwise <code>H5T_NORM_ERROR</code> (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetNorm">H5Tset_norm</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_norm</code>(<em>hid_t </em><code>type_id</code>,
        <em>H5T_norm_t</em> <code>norm</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets the mantissa normalization of a floating-point datatype.  
<dt><strong>Description:</strong>
    <dd><code>H5Tset_norm</code> sets the mantissa normalization of 
        a floating-point datatype.  Valid normalization types are:
        <ul> <dl>
            <dt>H5T_NORM_IMPLIED (<code>0</code>)
                <dd>MSB of mantissa is not stored, always 1
            <dt>H5T_NORM_MSBSET (<code>1</code>)
                <dd>MSB of mantissa is always 1
            <dt>H5T_NORM_NONE (<code>2</code>)
                <dd>Mantissa is not normalized
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to set.
        <dt><em>H5T_norm_t</em> <code>norm</code>
            <dd>Mantissa normalization type.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetInpad">H5Tget_inpad</a>
<dt><strong>Signature:</strong>
    <dd><em>H5T_pad_t </em><code>H5Tget_inpad</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves the internal padding type for unused bits in floating-point datatypes.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_inpad</code> retrieves the internal padding type for 
        unused bits in floating-point datatypes.
        Valid padding types are:
        <ul> <dl>
            <dt>H5T_PAD_ZERO (<code>0</code>)
               <dd>Set background to zeros.
            <dt>H5T_PAD_ONE (<code>1</code>)
               <dd>Set background to ones.
            <dt>H5T_PAD_BACKGROUND (<code>2</code>)
               <dd>Leave background alone.
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a valid padding type if successful;
        otherwise <code>H5T_PAD_ERROR</code> (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetInpad">H5Tset_inpad</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_inpad</code>(<em>hid_t </em><code>type_id</code>,
        <em>H5T_pad_t</em> <code>inpad</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Fills unused internal floating point bits.
<dt><strong>Description:</strong>
    <dd>If any internal bits of a floating point type are unused
        (that is, those significant bits which are not part of the
        sign, exponent, or mantissa), then <code>H5Tset_inpad</code> will be filled
        according to the value of the padding value property <code>inpad</code>.
        Valid padding types are:
        <ul> <dl>
            <dt>H5T_PAD_ZERO (<code>0</code>)
               <dd>Set background to zeros.
            <dt>H5T_PAD_ONE (<code>1</code>)
               <dd>Set background to ones.
            <dt>H5T_PAD_BACKGROUND (<code>2</code>)
               <dd>Leave background alone.
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to modify.
        <dt><em>H5T_pad_t</em> <code>pad</code>
            <dd>Padding type.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetCset">H5Tget_cset</a>
<dt><strong>Signature:</strong>
    <dd><em>H5T_cset_t </em><code>H5Tget_cset</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves the character set type of a string datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_cset</code> retrieves the character set type 
        of a string datatype.  Valid character set types are:
        <ul> <dl>
            <dt>H5T_CSET_ASCII (<code>0</code>)
               <dd>Character set is US ASCII
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a valid character set type if successful;
        otherwise <code>H5T_CSET_ERROR</code> (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetCset">H5Tset_cset</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_cset</code>(<em>hid_t </em><code>type_id</code>,
        <em>H5T_cset_t</em> <code>cset</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Sets character set to be used.
<dt><strong>Description:</strong>
    <dd><code>H5Tset_cset</code> the character set to be used.
        <p>
        HDF5 is able to distinguish between character sets of different
        nationalities and to convert between them to the extent possible.
        Valid character set types are:
        <ul> <dl>
            <dt>H5T_CSET_ASCII (<code>0</code>)
               <dd>Character set is US ASCII.
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to modify.
        <dt><em>H5T_cset_t</em> <code>cset</code>
            <dd>Character set type.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetStrpad">H5Tget_strpad</a>
<dt><strong>Signature:</strong>
    <dd><em>H5T_str_t </em><code>H5Tget_strpad</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves the string padding method for a string datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_strpad</code> retrieves the string padding method 
        for a string datatype.  Valid string padding types are:
        <ul> <dl>
            <dt>H5T_STR_NULL (<code>0</code>)
               <dd>Pad with zeros (as C does)
            <dt>H5T_STR_SPACE (<code>1</code>)
               <dd>Pad with spaces (as FORTRAN does)
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a valid string padding type if successful;
        otherwise <code>H5T_STR_ERROR</code> (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-SetStrpad">H5Tset_strpad</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tset_strpad</code>(<em>hid_t </em><code>type_id</code>,
        <em>H5T_str_t</em> <code>strpad</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Defines the storage mechanism for character strings.
<dt><strong>Description:</strong>
    <dd>The method used to store character strings differs with the 
        programming language: C usually null terminates strings while 
        Fortran left-justifies and space-pads strings.  
        <code>H5Tset_strpad</code> defines the storage mechanism for the string.
        Valid string padding values are:
        <ul> <dl>
            <dt>H5T_STR_NULL (<code>0</code>)
               <dd>Pad with zeros (as C does)
            <dt>H5T_STR_SPACE (<code>1</code>)
               <dd>Pad with spaces (as FORTRAN does)
        </dl> </ul>
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to modify.
        <dt><em>H5T_str_t</em> <code>strpad</code>
            <dd>String padding type.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetNmembers">H5Tget_nmembers</a>
<dt><strong>Signature:</strong>
    <dd><em>intn </em><code>H5Tget_nmembers</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves the number of fields in a compound datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_nmembers</code> retrieves the number of fields a compound datatype has.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns number of members datatype has if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetMemberName">H5Tget_member_name</a>
<dt><strong>Signature:</strong>
    <dd><em>char *</em> <code>H5Tget_member_name</code>(<em>hid_t </em><code>type_id</code>,
        <em>int</em> <code>field_idx</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Retrieves the name of a field of a compound datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_member_name</code> retrieves the name of a field 
        of a compound datatype.  Fields are stored in no particular 
        order, with indexes 0 through N-1, where N is the value returned 
        by <code>H5Tget_nmembers()</code>.  The name of the field is 
        allocated with <code>malloc()</code> and the caller is responsible 
        for freeing the memory used by the name.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
        <dt><em>int</em> <code>field_idx</code>
            <dd>Field index (0-based) of the field name to retrieve.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns a valid pointer if successful;
        otherwise NULL.
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetMemberDims">H5Tget_member_dims</a>
<dt><strong>Signature:</strong>
    <dd><em>int</em> <code>H5Tget_member_dims</code>(<em>hid_t </em><code>type_id</code>,
        <em>int</em> <code>field_idx</code>,
        <em>size_t *</em><code>dims</code>,
        <em>int *</em><code>perm</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Returns the dimensionality of the field.  
<dt><strong>Description:</strong>
    <dd><code>H5Tget_member_dims</code> returns the dimensionality of 
        the field.  The dimensions and permuation vector are returned 
        through arguments <code>dims</code> and <code>perm</code>, 
        both arrays of at least four elements.  
        Either (or even both) may be null pointers.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
        <dt><em>int</em> <code>field_idx</code>
            <dd>Field index (0-based) of the field <code>dims</code> 
                to retrieve.
        <dt><em>size_t *</em> <code>dims</code>
            <dd>Pointer to buffer to store the dimensions of the field.
        <dt><em>int *</em> <code>perm</code>
            <dd>Pointer to buffer to store the permutation vector of 
                the field.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns the number of dimensions, a number from 0 to 4, 
        if successful.
        Otherwise returns FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-GetMemberType">H5Tget_member_type</a>
<dt><strong>Signature:</strong>
    <dd><em>hid_t</em> <code>H5Tget_member_type</code>(<em>hid_t </em><code>type_id</code>,
        <em>int</em> <code>field_idx</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Returns the datatype of the specified member.
<dt><strong>Description:</strong>
    <dd><code>H5Tget_member_type</code> returns the datatype of the specified member.  The caller
        should invoke H5Tclose() to release resources associated with the type.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to query.
        <dt><em>int</em> <code>field_idx</code>
            <dd>Field index (0-based) of the field type to retrieve.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns the identifier of a copy of the datatype of the field
        if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Insert">H5Tinsert</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Tinsert</code>(<em>hid_t </em><code>type_id</code>,
        <em>const char *</em> <code>name</code>,
        <em>off_t</em> <code>offset</code>,
        <em>hid_t</em> <code>field_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Adds a new member to a compound datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tinsert</code> adds another member to the compound datatype
        <code>type_id</code>.  The new member has a <code>name</code> which
        must be unique within the compound datatype. 
        The <code>offset</code> argument defines the start of the member 
        in an instance of the compound datatype, and <code>field_id</code> 
        is the datatype identifier of the new member.
        <P>
        Note: All members of a compound datatype must be atomic; a
        compound datatype cannot have a member which is a compound 
        datatype.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of compound datatype to modify.
        <dt><em>const char *</em> <code>name</code>
            <dd>Name of the field to insert.
        <dt><em>off_t</em> <code>offset</code>
            <dd>Offset in memory structure of the field to insert.
        <dt><em>hid_t</em> <code>field_id</code>
            <dd>Datatype identifier of the field to insert.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Pack">H5Tpack</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Tpack</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Recursively removes padding from within a compound datatype.
<dt><strong>Description:</strong>
    <dd><code>H5Tpack</code> recursively removes padding from within a compound
        datatype to make it more efficient (space-wise) to store that data.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to modify.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-RegisterHard">H5Tregister_hard</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Tregister_hard</code>(<em>const char
        *</em> <code>name</code>, <em>hid_t </em><code>src_id</code>,
        <em>hid_t</em> <code>dst_id</code>,
        <em>H5T_conv_t</em> <code>func</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Registers a hard conversion function.  
<dt><strong>Description:</strong>
    <dd><code>H5Tregister_hard</code> registers a hard conversion function for a datatype
        conversion path.  The path is specified by the source and destination
        datatypes <code>src_id</code> and <code>dst_id</code>.  A conversion
        path can only have one hard function, so <code>func</code> replaces any
        previous hard function.
        <p>
        If <code>func</code> is the null pointer then any hard function
        registered for this path is removed from this path.  The soft functions
        are then used when determining which conversion function is appropriate
        for this path.  The <code>name</code> argument is used only
        for debugging and should be a short identifier for the function.
        <p>
        The type of the conversion function pointer is declared as:
        <br>
        <code>typedef</code> <em>herr_t </em>(<code>*H5T_conv_t</code>) (<em>hid_t </em><code>src_id</code>, 
                    <em>hid_t </em><code>dst_id</code>, 
                    <em>H5T_cdata_t *</em><code>cdata</code>,
                    <em>size_t </em><code>nelmts</code>, 
                    <em>void *</em><code>buf</code>, 
                    <em>void *</em><code>bkg)</code>;
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>const char *</em> <code>name</code>
            <dd>Name displayed in diagnostic output.
        <dt><em>hid_t</em> <code>src_id</code>
            <dd>Identifier of source datatype.
        <dt><em>hid_t</em> <code>dst_id</code>
            <dd>Identifier of destination datatype.
        <dt><em>H5T_conv_t</em> <code>func</code>
            <dd>Function to convert between source and destination datatypes.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-RegisterSoft">H5Tregister_soft</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Tregister_soft</code>(<em>const char
    *</em> <code>name</code>, <em>H5T_class_t </em><code>src_cls</code>,
        <em>H5T_class_t</em> <code>dst_cls</code>,
        <em>H5T_conv_t</em> <code>func</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Registers a soft conversion function.
<dt><strong>Description:</strong>
    <dd><code>H5Tregister_soft</code> registers a soft conversion function by adding it to the
        end of the master soft list and replacing the soft function in all
        applicable existing conversion paths.  The <code>name</code>
        is used only for debugging and should be a short identifier
        for the function.
        <P>
        The type of the conversion function pointer is declared as:
        <br>
        <code>typedef</code> <em>herr_t </em>(<code>*H5T_conv_t</code>) (<em>hid_t </em><code>src_id</code>, 
                    <em>hid_t </em><code>dst_id</code>, 
                    <em>H5T_cdata_t *</em><code>cdata</code>,
                    <em>size_t </em><code>nelmts</code>, 
                    <em>void *</em><code>buf</code>, 
                    <em>void *</em><code>bkg)</code>;
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>const char *</em> <code>name</code>
            <dd>Name displayed in diagnostic output.
        <dt><em>H5T_class_t</em> <code>src_cls</code>
            <dd>Identifier of source datatype class.
        <dt><em>H5T_class_t</em> <code>dst_cls</code>
            <dd>Identifier of destination datatype class.
        <dt><em>H5T_conv_t</em> <code>func</code>
            <dd>Function to convert between source and destination datatypes.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Unregister">H5Tunregister</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t</em> <code>H5Tunregister</code>(<em>H5T_conv_t</em> <code>func</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Removes a conversion function from all conversion paths.
<dt><strong>Description:</strong>
    <dd><code>H5Tunregister</code> removes a conversion function from all conversion paths.
        <P>
        The type of the conversion function pointer is declared as:
        <br>
        <code>typedef</code> <em>herr_t </em>(<code>*H5T_conv_t</code>) (<em>hid_t </em><code>src_id</code>, 
                    <em>hid_t </em><code>dst_id</code>, 
                    <em>H5T_cdata_t *</em><code>cdata</code>,
                    <em>size_t </em><code>nelmts</code>, 
                    <em>void *</em><code>buf</code>, 
                    <em>void *</em><code>bkg)</code>;
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>H5T_conv_t</em> <code>func</code>
            <dd>Function to remove from conversion paths.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


<hr>
<dl>
<dt><strong>Name:</strong> <a name="Datatype-Close">H5Tclose</a>
<dt><strong>Signature:</strong>
    <dd><em>herr_t </em><code>H5Tclose</code>(<em>hid_t </em><code>type_id</code>
    )
<dt><strong>Purpose:</strong>
    <dd>Releases a datatype.  
<dt><strong>Description:</strong>
    <dd><code>H5Tclose</code> releases a datatype.  Further access 
        through the datatype identifier is illegal.  Failure to release 
        a datatype with this call will result in resource leaks.
<dt><strong>Parameters:</strong>
    <dl>
        <dt><em>hid_t</em> <code>type_id</code>
            <dd>Identifier of datatype to release.
    </dl>
<dt><strong>Returns:</strong>
    <dd>Returns SUCCEED (0) if successful;
        otherwise FAIL (-1).
</dl>


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