| asmx | ASP.NET Web Service |
| aso | ActionScript Object |
| asp | Active Server Page |
| aspr | ASProtect Related Data |
| aspx | ASP.NET Page |
| asq | AcuSQL Precompiled File |
| asr | Flash Server-side ActionScript |
| asv | MATLAB AutoSave File |
| asx | Alpha Five Database Index |
| asz | AlphaControls Skin Package |
| atg | Coco/R Attributed Grammar File |
| atsln | Atmel Studio Solution File |
| au3 | AutoIt v3 Script |
| aub | Intel GPU Simulator Input |
| aut | AutoIt Script |
| autosave | GDevelop Autosave Data |
| avm | QAvimator Document |
| avrsln | Atmel Studio Legacy Solution File |
| awk | AWK Script |
| awl | Siemens AWL File |
| axb | Alpha Five Xbasic Script |
| axd | ASP.NET Trace Handler |
| axe | Annotated XML Example |
| axf | ARM RealView Compiler Object |
| aya | Ayauhteotl Parser Data |
| b2d | Brutus2D Source Code |
| b3d | Blitz3D Data |
| ba | BSC Intermediate Object |
| bal | B4A Layout |
| baml | Compiled XAML |
| bar | BREW MP Binary Application Resource |
| bash | Unix Shell Script |
| baz | Zebra Printer Basic Source Code |
| bb | GCOV BB Data FIle |
| bb | Blitz Basic Code |
