address is
        checked against 0 and -1 only.</dd>
    </dl>
    <p>All other class methods are <a href="#datastream_methods">described
        above</a>.<br>
      This class does not implement fname() and subfile_open() calls, so
      external JPEG metadata parsing is not possible.</p>
    <p><a name="own_datastreams"></a></p>
    <h3>Own datastream derived classes</h3>
    <p>To create own read interface LibRaw user should implement C++ class
      derived from <strong>LibRaw_abstract_datastream</st