Solution : https://service.sap.com/sap/support/notes/174699 (SAP Service marketplace login required)
Key words :
enhance object component'interface import/export parameter', type optionaldoc_number vbrk-vbeln 2, user exit customer-function '008', additional key words vf01, transaction se37 'function builder', processed billing document number, import parameter ref, interface table cvbrp, function module exit_saplv60b_008, dummy number $00000000n
Related Notes :
| 186240 | CUSTOMER-FUNCTIONs without processed document number |
| 182041 | Note correct:CUST-FUNCTION '008' w/o proc. doc. no. |
| 78013 | Enhancing user exits w. VBRP, KOMV in SAPLV60B |