/**
  * export structure objects to xml (see ilias_co.dtd)
  *
  * @param	object		$a_xml_writer	ilXmlWriter object that receives the
  *										xml data
  */
 function exportXMLStructureObjects(&$a_xml_writer, $a_inst, &$expLog)
 {
     include_once "Services/MetaData/classes/class.ilMD2XML.php";
     $tree = new ilTree($this->getId());
     $tree->setTableNames('sahs_sc13_tree', 'sahs_sc13_tree_node');
     $tree->setTreeTablePK("slm_id");
     $a_xml_writer->xmlStartTag("StructureObject");
     foreach ($tree->getFilteredSubTree($tree->getRootId(), array('page')) as $obj) {
         if ($obj['type'] == '') {
             continue;
         }
         //$md2xml = new ilMD2XML($obj['obj_id'], 0, $obj['type']);
         $md2xml = new ilMD2XML($this->getId(), $obj['obj_id'], $obj['type']);
         $md2xml->setExportMode(true);
         $md2xml->startExport();
         $a_xml_writer->appendXML($md2xml->getXML());
     }
     $a_xml_writer->xmlEndTag("StructureObject");
 }