| Abbreviation | Definition |
|---|---|
| ASV | Advance Server for VMS |
| ATA | Advanced Technololgy Attachment |
| ATB | Associative Topology Bus |
| ATCP | AppleTalk Control Protocol |
| ATDN | AOL Transit Data Network |
| ATH | Asynchronous Task Handling |
| ATL | Automated Tape Library |
| ATP | Appletalk Transaction Protocol |
| ATP | Asymmetric Transport Protocol |
| ATS | Asynchronous Time Sharing |
| ATSU | Access Technology Support Unit |
| ATU | Average Total Usage |
| AU | Amiga Usenet |
| AUA | Authorized User Address |
| AUC | Authenticated User Community |
| AUN | Acorn Universal Networking |
| AUP | Acceptable Use Policy |
| AUP | All Users Policy |
| AUPU | Average Usage Per User |
| AURP | Appletalk Update-based Routing Protocol |