Ledger type in F0902

Hello ,

While creating a purchase order via P4310/ R4311Z1, it is noticed that it creates an entry in F0902 but with blank ledger type. I am assuming I is booking the liability in form of commitments.

I understand that this checks UDC 40/CT. But why does it create a "Blank" ledger type entry?

Should it not be a PA/PU or AA/AU?

Can anyone advise me on this topic.?

Thanks.