| a5wcmp | Alpha Five Web Publishing Component |
| a65 | Adobe Authorware 6.5 Library |
| a66 | µVision Assembler Source Code |
| a6l | Adobe Authorware Library |
| a6m | Macromedia Authorware Macintosh File |
| a6p | Macromedia Authorware Source |
| a6w | Macromedia Authorware Windows File |
| a7e | Macromedia Authorware Packaged Library |
| a7l | Adobe Authorware Library |
| a7m | Macromedia Authorware Macintosh File |
| a7p | Macromedia Authorware Source |
| a7w | Macromedia Authorware Windows File |
| a86 | A86 Assembly Souce Code |
| aah | Amazingly Abstracted HTML Document |
| aapkg | ArchestrA IDE Package |
| ab | Applix Builder Data |
| ab2 | Blitz Basic Code |
| abap | ABAP Source Code |
| abm | Alpha Five Database Export |
| abn | Alpha Five Database Export |
| abo | Applix Builder Object |
| ac | GNU Autoconf Input File |
| accessor | Visual Studio Accessor Data |
| acme | ACME Assembler Source Code |
| acsup | Avaya CMS Script |
| actx | DS Game Maker Action Description |
| acu | ACUCOBOL-GT Compiled Program |
| acx | WebFOCUS Data Description |
| ad | DSM Application Diagram |
| ada | Ada Source Code |
| adb | Ada Implementation File |
| adb | Alpha Five Database |
| adblock | Alpha Five Database Lock |
| adcp | Adobe Device Central Project |
| addin | Visual Studio Add-in Definition |
