G-1 means Army or Marine Corps Component Manpower or Personnel Staff Officer Army Division or Higher Staff, Marine Corps Brigade or Higher Staff in Military
Similar to G-1
407 RRD - 407th Radio Research Detachment 442 RCT - 442nd Regimental Combat Team 48 FW - 48th Fighter Wing 4ID - 4th Infantry Division 4WW - The Fourth World War 503 RCT - 503rd Regimental Combat Team 517 PRCT - 517th Parachute Regimental Combat Team