protected function addAppointmentsToModel()
    {
        $model = new \MUtil_Model_TableModel('gems__track_appointments');
        \Gems_Model::setChangeFieldsByPrefix($model, 'gtap');

        $map = $model->getItemsOrdered();
        $map = array_combine($map, str_replace('gtap_', 'gtf_', $map));
        $map['gtap_id_app_field'] = 'gtf_id_field';

        $this->addUnionModel($model, $map, self::APPOINTMENTS_NAME);

        $model->addColumn(new \Zend_Db_Expr("'appointment'"), 'gtf_field_type');
        $model->addColumn(new \Zend_Db_Expr("NULL"), 'gtf_field_values');
        $model->addColumn(new \Zend_Db_Expr("NULL"), 'gtf_field_default');
        $model->addColumn(new \Zend_Db_Expr("NULL"), 'gtf_calculate_using');
    }