I want to know if the SAP document number would be available during the subsitution. I want to concatenate the document number field with a couple of other fields and subsititute the Payment reference field. But I am not able to get the document number at the time of subsitution. The field is still blank. It seems the document number has not yet been reserved by the time the subsitution gets triggered. Is there any other way I can access the document number before the posting so that I can subsitute the field? thanks.