public function getXIncludeNamespace(){
        $ns = '';
        $relatedItem = $this->getRelatedItem();
        if(!is_null($relatedItem)){
            foreach($relatedItem->getNamespaces() as $name => $uri){
                if(strpos($uri, 'XInclude') > 0){
                    $ns = $name;
                    break;
                }
            }
        }
        return $ns;
    }