[1] Access Control Store/Set (unter ISO/OSI VT)

[2] Access Control System (->"Computer Security Basics", Russell/Gangemi, ORA 1991)

[3] Access Control Server (Cisco)

[4] Advanced Communication Service (Bell, AT&T)

[5] Advanced Communication Set

[6] Advanced Communications System

[7] Application Control Services/Set

[8] Automatic Crossconnect System

[9] Alaska Communications Systems (siehe ALASCOM)

[10] Arcus Cosinus (vergl. arccos)

[11] Australian Computer Science

[12] Assembly Contingency Subsystem (Space Shuttle) {Weltraumfahrt}.