| Abbreviation | Definition |
|---|---|
| BSY | Busy flag (FTN soft) |
| BTL | Inmos bootable file |
| BTM | Batch To Memory Batch file |
| BTN | Button file (Makeover) |
| BUB | Photobubble (IPIX) |
| BUFR | Binary Universal Form for the Representation |
| BUFR | Meteorological Data |
| BUG | Bugs and Problems |
| BUN | Bundle file (CakeWalk Audio) |
| BUP | Backup |
| BUT | Button definitions (Buttons!) |
| BV1 | Overflow file below insert point in Doc 1 (WordPerfect for Win) |
| BV2 | Overflow file below insert point in Doc 2 (WordPerfect for Win) |
| BV3 | Overflow file below insert point in Doc 3 (WordPerfect for Win) |
| BV4 | Overflow file below insert point in Doc 4 (WordPerfect for Win) |
| BV5 | Overflow file below insert point in Doc 5 (WordPerfect for Win) |
| BV6 | Overflow file below insert point in Doc 6 (WordPerfect for Win) |
| BV7 | Overflow file below insert point in Doc 7 (WordPerfect for Win) |
| BV8 | Overflow file below insert point in Doc 8 (WordPerfect for Win) |
| BV9 | Overflow file below insert point in Doc 9 (WordPerfect for Win) |