function _toXML(DOMNode $node, $hl7_datatypes, $encoding)
 {
     $doc = $node->ownerDocument;
     $field = $this->getField();
     $new_node = $doc->createElement($field->name);
     parent::_toXML($new_node, $hl7_datatypes, $encoding);
     $node->appendChild($new_node);
 }
 function getPath($separator = ".", $with_name = false)
 {
     $path = $this->parent->getPath($separator, $with_name);
     $label = $this->self_pos + 1;
     if ($with_name) {
         $label = "{$this->datatype}.{$label}";
     }
     $path[] = $label;
     return $path;
 }