Aeronautics active control system
• Additional Curates Society
• Admiral Commanding Submarines
• Admiralty computing service
• advanced communications system
• airport catering services
• air-conditioning system
• Aeronautics altitude control system
• American Cancer Society
• American Ceramic Society
• American Chemical Society
• American College of Surgeons
• assembly control system
• Associate in Commercial Science
• Association of Caribbean States
• Australian Computer Society
• Finance automated confirmation service
• Computing automated control system