| LabVIEW Library Backup Format | |
| National Instruments | |
| Ads |
| .ab | Google Android Debug Bridge Backup Format |
| .aba | Palm Address Book Archive Format |
| .abbu | Apple Address Book Archive Format |
| .abf | Adobe Binary Screen Font Format |
| .abk | Ability Write Backup Format |
| .acp | Alfresco Exported Repository Format |
| .adi | Active@ Disk Image Format |
| .aea | Ae Timer Alarm Document Format |