Front of Japanese Military Aircraft, ONI 232 Identification and Characteristics Section. ONI 232 was a US Office of Naval Intelligence publication that provided identification and characteristics information on Japanese military aircraft during World War II. It was a key resource for Allied forces in recognizing and understanding Japanese aircraft. The Japanese military aircraft designation systems for the Imperial period (pre-1945) had multiple designation systems for each armed service. This led to the Allies’ use of code names during World War II, and these code names are still better known in English-language texts than the real Japanese names for the aircraft. A number of different schemes were simultaneously in use. Imperial Japanese Navy Air Service The Imperial Japanese Navy Air Service (Dai-Nippon Teikoku Kaigun Koukuu-tai) (IJNAS) used several different aircraft designation systems simultaneously. Between 1931 and 1945, aircraft had Shi numbers designating the specifica...