function createXprop() {
    if( 0 >= count( $this->xprop ))
      return;
    $xprop = null;
    foreach( $this->xprop as $label => $xpropPart ) {
      $attributes = $this->_createParams( $xpropPart['params'], array( 'LANGUAGE' ));
      if( is_array( $xpropPart['value'] )) {
        foreach( $xpropPart['value'] as $pix => $theXpart )
          $xpropPart['value'][$pix] = $this->_strrep( $theXpart );
        $xpropPart['value']  = implode( ',', $xpropPart['value'] );
      }
      else
        $xpropPart['value'] = $this->_strrep( $xpropPart['value'] );
      $xprop .= $this->_createElement( strtoupper( $label ), $attributes, $xpropPart['value'] );
    }
    return $xprop;
  }