Edit: we are on version 15.2.0.1
Currently testing v15-.2 before upgrade, and we find taht if we add a manual PO number on a sales order, Astea will try to look it up. Even if PO is not mandatory for the customer. Most of our sale require POs, but very seldom blanket POs
Entering PO:
Astea looks it up:
Hitting Close: