public function set_from_input($_INPUT = array(), $pre = '')
 {
     try {
         if (parent::set_from_input($_INPUT, $pre)) {
             if (isset($_INPUT[$pre . 'delta'])) {
                 $this->set_delta($_INPUT[$pre . 'delta']);
             }
             if (isset($_INPUT[$pre . 'i_effective'])) {
                 $this->set_i_effective($_INPUT[$pre . 'i_effective']);
             }
             return true;
         } else {
             return false;
         }
     } catch (Exception $e) {
         throw new Exception(wfMessage('fm-exception-in') . " " . __FILE__ . ": " . $e->getMessage());
     }
 }