;&nbsp;&nbsp;&nbsp;}<br>
 &nbsp;&nbsp;&nbsp;&nbsp;break;<br>
 &nbsp;&nbsp;&nbsp;default:<br>
 &nbsp;&nbsp;&nbsp;&nbsp;return null;<br>
 &nbsp;&nbsp;}<br>
 &nbsp;}</code><p>
The application can also use this interface to redirect system identifiers to local URIs or to look up replacements in a catalog (possibly by using the public identifier).<p>
The <a class="el" href="classHandlerBase.html" title="Default base class for handlers.">HandlerBase</a> class implements the default behaviour for this interface, w