The hits just keep coming with Microsoft Dynamics GP 2013 R2 Feature of the Day: Purchase Order Prepayment Additions
Microsoft Dynamics GP 2013 R2 Feature of the Day: Purchase Order Prepayment Additions – Inside Microsoft Dynamics GP
Tips & Hidden FeaturesSales, Purchasing & InventoryGP 2013
Archived post from 2014. Dynamics GP and the links it points to have changed since; check current documentation before relying on version-specific steps.