Solution : https://service.sap.com/sap/support/notes/81017 (SAP Service marketplace login required)
Key words :
additional key words customer-function, internal buffer tables, batch number assignment, final order number, temporary order number, order number, process order, user exits, bncom-aufnr, xbncom-aufnrcor1
Related Notes :
372819 | Order item is not transferred to X_BNCOM |
44308 | Batch determ:error in search strategy in prod.order |