| a26 | Atari 2600 ROM Image |
| a2c | Alice v2 Object |
| a2desktop | Aston 2 Desktop Theme File |
| a2menu | Aston 2 Menu Theme File |
| a2panel | Aston 2 Panel Theme File |
| a2theme | Aston 2 Theme File |
| a3c | Alice v3 Class |
| a3e | Autodesk Showcase Environments |
| a3s | Autodesk Showcase 3D Scene |
| a52 | Atari 5200 ROM Image |
| a5d | Macromedia Authorware Model |
| a65 | Authorware 6.5 |
| a6d | Macromedia Authorware Model |
| a78 | Atari 7800 ROM Image |
| a7d | Macromedia Authorware Model |
| aaa | SQL Anywhere Temporary File |
| aab | Adobe Authorware Binary Map |
| aae | Apple iOS8 Sidecar File |
| aag | GlobDEM50 Data |
| aal | Agent Animation List |
| aam | Adobe Authorware Map |
| aama | Optitex 3D Suite Grading File |
| aan | Avid Pro Tools Analysis Data |
| aao | Agenda At Once Database |
| aas | Adobe Authorware Segment File |
| aat | ArchiCAD Attributes Data |
| aatrend | ActiveFactory Trend Data |
| aawdef | Ad-Aware Definitions Data |
| ab1 | DNA Electropherogram File |
| ab3 | PhotoImpact 3 Album |
