protected function _buildXMLAdditional( MShop_Common_Manager_Interface $orderBaseManager,
		MShop_Order_Item_Base_Interface $base, DOMDocument $dom, DOMElement $orderitem )
	{
		$orderCouponManager = $orderBaseManager->getSubManager( 'coupon' );
		$criteria = $orderCouponManager->createSearch();
		$criteria->setConditions( $criteria->compare( '==', 'order.base.coupon.baseid', $base->getId() ) );
		$criteria->setSortations( array( $criteria->sort( '+', 'order.base.coupon.code' ) ) );
		$coupons = $orderCouponManager->searchItems( $criteria );

		$additional = $dom->createElement( 'additional' );
		$this->_appendChildCDATA( 'comment', '', $dom, $additional );

		$couponItem = $dom->createElement( 'discount' );

		foreach( $coupons as $coupon ) {
			$this->_appendChildCDATA( 'code', $coupon->getCode(), $dom, $couponItem );
		}

		$additional->appendChild( $couponItem );
		$orderitem->appendChild( $additional );
	}