Solution : https://service.sap.com/sap/support/notes/65988 (SAP Service marketplace login required)
Key words :
additional key words por, print report rsnast00, schedule transaction vf31, choose dispatch time '1', choose dispatch time '3', dispatch time '4', por invoice, fi document, automatically generated, billing document
Related Notes :
81687 | Billing document printout - collective note |
80415 | POR procedure - collective note |