protected function getDefault($name)
  {
    if (is_null($this->_defaultData)) {
      $subject = $this->getSubject();
      if (!is_null($subject) && $subject instanceof Options_Subject) {
        $this->_defaultData = $subject->getDefaultOptions();
      } else {
        $this->_defaultData = array();
      }
    }
    
    if (isset($this->_defaultData[$name])) {
      $value = $this->_defaultData[$name];
    } else {
      $value = null;
    }
    
    return $value;
  }