| Abbreviation | Definition |
|---|---|
| ACM | Audio Compression Module add-on (Windows) |
| ACM | Graphics file (ACMB format) |
| ACMB | Graphics file (ACMB format) |
| ACO | Adobe Color Palette |
| ACP | ACB Compressed file archive |
| ACP | Microsoft Office Assistant Preview file |
| ACR | ACR-NEMA medical image file Bitmap graphics |
| ACT | Action! Presentation file |
| ACT | Adobe Photoshop Color Table |
| ACT | Animation Works Actor source code file (Graphics cell) |
| ACT | FoxPro Foxdoc Action Diagram |
| ACT | Microsoft Office Assistant ACTor file |
| ACV | OS/2 Audio Compress and decompress audio data driVer |
| AD | AfterDark Screensaver |
| AD2 | ZFAX ADPCM 2-bit compressed voice file |
| AD3 | ZFAX ADPCM 3-bit compressed voice file |
| ADA | Ada language source code file |
| ADB | Ada Package Body |
| ADB | Appointment database (HP 100LX organizer) |
| ADC | After Dark Charlie |