=Office of Technical Cooperation技朮合作處(聯合國)

Office of Technical Cooperation技朮合作處(聯合國);

Office of Transport and Communications交通運輸處[美];

Officers'Training Corps 軍官訓練團;

Overseas Telecommunications Commission 海外電信委員會[澳];

Oxytetracycline【藥】氧四環素, 土霉素