APO (Army Post Office) / FPO (Fleet Post Office) represents the Military Postal Center code for military postal locations outside the continental United States (OCONUS) corresponding to the shipment's destination. Army and Air Force locations use APO, and Navy, USMC, and Coast Guard use FPO designations (DoD 4525.6-M). This field will also contain the MPSA pseudo-state code of AA, AE, or AP.