function createCategories() {
    $cnt = count( $this->categories );
    if( 0 >= $cnt )
      return;
    $output = null;
    foreach( $this->categories as $category ) {
      $attributes = $this->_createParams( $category['params'], array( 'LANGUAGE' ));
      if( is_array( $category['value'] )) {
        foreach( $category['value'] as $cix => $categoryPart )
          $category['value'][$cix] = $this->_strrep( $categoryPart );
        $content  = implode( ',', $category['value'] );
      }
      else
        $content  = $this->_strrep( $category['value'] );
      $output    .= $this->_createElement( 'CATEGORIES', $attributes, $content );
    }
    return $output;
  }