List of USAAF squadron codes
This is an incomplete list of squadron codes used by United States Army Air Forces (USAAF) heavy bomber aircraft operating in Europe during World War II. == Squadron codes == For each squadron code—painted on the plane's fuselage—the associated bombardment squadron (BS) is listed, along with the squadron's bombardment group (BG). Most commonly, a group would have four squadrons.
Source: Wikipedia — List of USAAF squadron codes (CC BY-SA 4.0)