If unpaid invoice, use GLS900 to reverse the invoice
If paid, reverse the payment and invoice not allowed
Check APS370 : If no movement in accounts => close the PO // difference in industrial accounting so OD on stock account (CAS950 ledger)
APS370 related / invoice closing line => PO line closed / FNP line status 9 / balance in APS370 / CAS950 accounting entry to correct / check in CAS300 (PP25 = correction)