Right now we're stuck with only F.O.B incoterm with an editable field. In practice F.O.B should be called 'Shipment Term', then with the editable field to input the appropriate Incoterm (ie: FOB, CIF, EXW, etc). Also allow to set default value of this new 'Shipment Term' at the Customer module, and not as a general setting under System Setup as it does now (with the F.O.B default value).
The best way is to treat it like the Edit settings for 'Ship Via' and 'Terms', where user can set up any number and types of Incoterms as they see fit, then be able to apply it in Customer module and/or Order Entry module.