| Abbreviation | Definition |
|---|---|
| B4 | Nuts and Bolts file (Helix) |
| B4A | Basic4Android |
| B64 | Base64 MIME Encoded file archive (ASCII) |
| B8 | Bitmap graphics (one byte per pixel) plane two (PicLab) |
| B8 | Red channel image data (24bit 3D animation) (Cubicomp PictureMaker) |
| BAC | Backup |
| BAD | Bad file (Oracle) |
| BAK | Backup |
| BAL | Ballade Music score file |
| BAR | dBASE Application Generator horizontal BAR menu object file |
| BAR | Horizontal bar menu object file (dBASE Application Generator) |
| BAR | Unix BAR archive Compressed file archive |
| BAS | BASIC language source code file ( QuickBASIC - GW-BASIC) |
| BAT | Batch file (DOS) |
| BB | Papyrus DataBase Backup |
| BBeB | Broad Band eBook |
| BBL | Bibliographic reference (TeX/BibTeX) |
| BBL | TeX/BibTeX BiBLiographic reference file |
| BBM | Brush (Deluxe Paint) |
| BBNNG | Bitmap graphics (BBN BitGraph terminal Display Pixel Data (DPD) sequence) |