| 1. | A | Ada source code Assembly source code (Macintosh) Object library (Unix) |
| 2. | A01 | ARJ multiple disk archive, disk 2 |
| 3. | A02 | ARJ multiple disk archive, disk 3 |
| 4. | A03 | ARJ multiple disk archive, disk 4 |
| 5. | A04 | ARJ multiple disk archive, disk 5, etc. |
| 6. | A11 | |
| 7. | A31 | |
| 8. | A3M | Unpackaged file (Authorware for Macintosh) |
| 9. | A3W | Unpackaged file (Authorware for Windows) |
| 10. | A41 | |
| 11. | A4M | Unpackaged file (Authorware for Macintosh) |
| 12. | A4P | Package without runtime (Authorware) |
| 13. | A4W | Unpackaged file (Authorware for Windows) |
| 14. | A51 | |
| 15. | A5W | Unpackaged file (Authorware for Windows) |
| 16. | A8 | Cubicomp PictureMaker alpha channel image data (24bit 3D animation) |
| 17. | A86 | A86 assembly language source code file |
| 18. | AAC | Homeboy reference (music) |
| 19. | AAM | |
| 20. | AAS | Authorware Shocked packet |