If customer would like to track data that does not have a location natively in GP can use Extender for this purpose avoiding customization.
Two GP customer examples:
Nachurs uses a window tied to the Sales Transaction Entry to track what SO's in US company are associated with PO's in Nachurs' Canadian company in GP)
Bass Security uses an Extender window tied to work order entry (Service Call Entry/Update) to track shipping information for shipments that originated from a work order.