public function getAnnotationType($pn_representation_id = null)
 {
     if (!$pn_representation_id) {
         if (!($vn_representation_id = $this->get('representation_id'))) {
             return false;
         }
     } else {
         $vn_representation_id = $pn_representation_id;
     }
     $t_rep = new ca_object_representations();
     return $t_rep->getAnnotationType($vn_representation_id);
 }