You may use this optional parameter so that
simplexml_import_dom() will return an object of
the specified class. That class should extend the
SimpleXMLElement class.
Return Values
Returns a SimpleXMLElement or FALSE on failure.
Examples
Example #1 Importing DOM
<?php $dom = new DOMDocument; $dom->loadXML('<books><book><title>blah</title></book></books>'); if (!$dom) { echo 'Error while parsing the document'; exit; }