Canceling a Billing Request
You may want to cancel the billing document if you do not want to process the items in a billing request or if you want to make them available for a new billing request.
For technical reasons, you can not use the cancel function. You can, however, provide it with a suitable reason for rejection. This means that it will not be taken into account in the current billing document but it will be available for billing in subsequent billing documents.
You can define reasons for rejection in the online Implementation Guide.