public function rules()
{
// NOTE: you should only define rules for those attributes that
// will receive user inputs.
return array(array('parent_id', 'required'), array('disorder_id, finding_id, parent_id', 'length', 'max' => 10), array('disorder_id, finding_id, parent_id, letter_macro_text', 'safe'), array('id, disorder_id, finding_id', 'safe', 'on' => 'search'));
}