Where oh Where is the PONum Field for AR Invoice Line

Vantage 8 allows multiple PONum's per Sales Order, and per AR Invoice.
When using this "feature" with AR Invoice, the header PONum is '****'.

Anybody know where in the db Epicor is hiding the line related PONum?

Seems like it should be in the InvcDtl table...

In the ARForm Report Data Def they pass it as a calculated field -
ponum.

Thanks in advance for any help!