| a1wish | Audials One Wishlist |
| a26 | Atari 2600 ROM Image |
| a2c | Alice v2 Object |
| a2desktop | Aston 2 Desktop Theme File |
| a2m | SAM Alignment Data |
| 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 |
| a3g | Photo! 3D Album Gallery |
| a3s | Autodesk Showcase 3D Scene |
| a52 | Atari 5200 ROM Image |
| a5d | Macromedia Authorware Model |
| a5e | Macromedia Authorware v5 Packaged Library |
| a64rpt | AIDA64 Report |
| a6d | Macromedia Authorware Model |
| a78 | Atari 7800 ROM Image |
| a7d | Macromedia Authorware Model |
| a8 | Cubicomp PictureMaker Animation Data |
| 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 |
| aapp | Adobe Acrobat AcroApp Script |
| aard | AARD Dictionary Data |
| aas | Adobe Authorware Segment File |
| aat | ArchiCAD Attributes Data |
| aatrend | ActiveFactory Trend Data |
| aaui | Adobe Acrobat User Interface Data |