function deleteProperty( $propName, $propix=FALSE ) {
    $propName = ( $propName ) ? strtoupper( $propName ) : 'X-PROP';
    if( !$propix )
      $propix = ( isset( $this->propdelix[$propName] )) ? $this->propdelix[$propName] + 2 : 1;
    $this->propdelix[$propName] = --$propix;
    $return = FALSE;
    switch( $propName ) {
      case 'CALSCALE':
        $this->calscale = null;
        $return = TRUE;
        break;
      case 'METHOD':
        $this->method   = null;
        $return = TRUE;
        break;
      default:
        if( $propName != 'X-PROP' ) {
          if( !isset( $this->xprop[$propName] )) return FALSE;
          unset( $this->xprop[$propName] );
          $return = TRUE;
        }
        else {
          if( count( $this->xprop ) <= $propix )  return FALSE;
          $xpropno = 0;
          foreach( $this->xprop as $xpropkey => $xpropvalue ) {
            if( $propix == $xpropno ) {
              unset( $this->xprop[$xpropkey] );
              $return = TRUE;
              break 2;
            }
            else
              $xpropno++;
          }
        }
    }
    return $return;
  }