public function saveXml()
    {
        // Return a complete document including XML prologue.
        $doc = new DOMDocument($this->_element->ownerDocument->version,
                               $this->_element->ownerDocument->actualEncoding);
        $doc->appendChild($doc->importNode($this->_element, true));
        $doc->formatOutput = true;

        return $doc->saveXML();
    }