Which retail innovation was first widely adopted by Army & Air Force Exchange Service (AAFES) stores in the 1980s, years before becoming standard in civilian retail?

The military exchange system has a fascinating history of retail innovation. Post exchanges (PX) and base exchanges (BX) have evolved from simple trading posts to sophisticated retail operations that rival civilian counterparts. This trivia question explores a groundbreaking retail technology first widely implemented in military exchanges before becoming standard in civilian retail.

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Barcode scanners at checkout
Universal Product Code (UPC) implementation
Electronic point-of-sale systems with integrated inventory management
Self-checkout kiosks