| axdt | ANSYS External Data |
| axe | Autoroute Export Data |
| axis | Microsoft SSAS AXIS Data |
| axm | AXMEDIS Object |
| axq | EditRocket Ada Editor Data |
| axs | AXIS Data File |
| axt | Adobe Photoshop Replace Color Setup |
| axtr | Microsoft Dynamics AX Task Recording Package |
| axw | Analyzer StateForms Data |
| ayt | Ayat Data |
| ayu | AY Paste Data |
| ayy | FSUTMS Binary Transit Plotting Model |
| azf | AirZip FileSECURE AZF File |
| azk | DMDX Output Document |
| azs | AirZip FileSECURE AZS File |
| azt | AutoZilla Template File |
| azz | AZZ Cardfile Database |
| b1 | VTrain Data File |
| b1j | BookJones Data |
| b2 | VTrain Data File |
| b2a | Btoa Encoded File |
| b3 | VTrain Data File |
| b3d | Blitz3D Object |
| b4 | VTrain Data File |
| b4a | Native Instruments B4 II Data |
| b5 | VTrain Data File |
| b64 | Base64 Encoded Data |
| b6l | BlindWrite License Data |
| b8 | Cubicomp PictureMaker Blue Channel Image Data |
| b84 | TI-84 Plus CE Bundle Image |
| bab | Babble Data |
| bac | Avantrix Backup Plus Backup Data |
| back | RMCProfile Coefficient Data |
| bad | Microsoft Exchange Non-Delivery Report Message |
| bad | Brutus Application Definition |
