function createRelatedTo() {
    $cnt = count( $this->relatedto );
    if( 0 >= $cnt )
      return;
    $output = null;
    foreach( $this->relatedto as $relation ) {
      $attributes = $this->_createParams( $relation['params'] );
      $content    = '<'.$this->_strrep( $relation['value'] ).'>';
      $output    .= $this->_createElement( 'RELATED-TO', $attributes, $content );
    }
    return $output;
  }