| b2f | RISC OS Windows Metafile |
| b3 | VTrain Box Data |
| b3 | VTrain Data File |
| b3 | VTrain Vocabulary Trainer Data |
| b3d | Blitz3D Object |
| b3dm | Cesium Batched 3D Tiles Data |
| b4 | VTrain Box Data |
| b4 | VTrain Data File |
| b4 | VTrain Vocabulary Trainer Data |
| b4a | Native Instruments B4 II Data |
| b4p | Native Instruments B4 II Presets Data |
| b5 | VTrain Box Data |
| b5 | VTrain Data File |
| b5 | VTrain Vocabulary Trainer Data |
| b5l | BlindWrite 5 License Data |
| b64 | Base64 Encoded Data |
| b6l | BlindWrite License Data |
| b8 | Cubicomp PictureMaker Blue Channel Image Data |
| b84 | TI-84 Plus CE Bundle Image |
| ba1 | Windows Media Center Report Log |
| ba6 | TaxACT 2016 Tax Return Backup Data |
| ba7 | TaxACT 2017 Tax Return Backup Data |
| ba8 | TaxACT 2018 Tax Return Backup Data |
| ba9 | TaxACT 2019 Tax Return Backup Data |
| bab | Babble Data |
| babl | DeBabelizer Pro Data |
| bac | Avantrix Backup Plus Backup Data |
| back | RMCProfile Coefficient Data |
| backpack | Mammoet Backpack Word List |
| backupdb | Time Machine Backup Folder |
| bad | Brutus Application Definition |
| bad | Microsoft Exchange Non-Delivery Report Message |
| bada | Bada Data |
| badongo | Badongo File Info |
| bafl | BurnAware File List |