/**
  * prepare the rule
  *
  * @access     public
  * @param      object patForms
  */
 function prepareRule(&$container)
 {
     patForms_Rule::prepareRule($container);
     $onChange = $container->getAttribute('onchange');
     $newHandler = sprintf('pfr_%s.validate();', $this->_id);
     $container->setAttribute('onchange', $newHandler . $onChange);
     return true;
 }