| bkl | KeyCarbon Binary Keystroke Log |
| bkmk | Yummy FTP Pro Bookmark |
| bkp | Steinberg WaveLab Backup Plan |
| bkr | BK ReplaceEm Fileset |
| bksln | Freescale BeeKit Solution File |
| bkt | Zortech 3 Tools Samples Data |
| bku | Sage Timeslips Backup |
| bkup | Groundspeak Wherigo Backup File |
| bky | SmartWare Backup Keyboard Data |
| bkz | FileFort Backup |
| bla | Blaise Datamodel |
| blb | Treepad Database Blob Data |
| blb | Act! Blob Data |
| blend1 | Blender Document Backup |
| blend2 | Blender Document Backup 2 |
| blf | MasterWorks Data |
| blf | CLFS BaseLog |
| blif | Berkeley Logic Interchange Format Data |
| blk | Lightscape Block File |
| blm | Rightmove Bulk Load Mass Data |
| bln | Golden Software Blanking |
| blo | IBM DB2 Binary Large Object Data |
| blob | IBM DB2 Binary Large Object Data |
| blob | Valve Steam Client Registry Data |
| blockplt | Lego Mindstorms NXT Block Palette Data |
| blogthis | Windows Live Writer Data |
| blr | Biacore BIAlite Project Data |
| blrb | Apple Extensions Manager Info Data |
| blt | AOL Instant Messenger Buddy List File |
| blwd | Claris Home Page Data |
