protected function getCouponCodeDiscountLine()
    {
        $result = array(
            Tag::ItemNumber => $this->order['details']['BT']->coupon_code,
            Tag::Product => $this->t('discount'),
            Tag::Quantity => 1,
            Meta::UnitPriceInc => (float) $this->order['details']['BT']->coupon_discount,
            Tag::VatRate => null,
            Meta::VatRateSource => static::VatRateSource_Strategy,
            Meta::StrategySplit => true,
        );

        return $result;
    }