| bk6 | Corel WordPerfect Document Backup |
| bk7 | Corel WordPerfect Document Backup |
| bk8 | Corel WordPerfect Document Backup |
| bk9 | Corel WordPerfect Document Backup |
| bkn | Corel WordPerfect Document Backup |
| bll | Binary Lasergraphics Language Document |
| blogthis | Windows Live Writer Data |
| blurb | BookWright Document |
| bmml | Braille Music Markup Language File |
| bn | NewsRoom Document |
| bna | Barna Word Processor Document |
| bnk | ExamView Question Bank |
| bnr | Banner Mania Banner |
| bns | BinNews BNS Message-Id Data |
| bobo | ClarisWorks Data |
| boc | EasyWord Big Document |
| book | Adobe FrameMaker Book |
| bop | Business Office Pro Document |
| bpdx | Adobe Acrobat Batch PDX Data |
| bpmn | Business Process Model and Notation Document |
| bps | Microsoft Works Document Backup |
| bpt | IBM InfoSphere Blueprint Director Document |
| br2 | Bryce 2 Scene |
| br3 | Bryce 3 Scene |
| br4 | Bryce 4 Scene |
| br5 | Bryce 5 Scene |
| br6 | Bryce 6 Scene |
| br7 | Bryce 7 Scene |
| brc | Bryce 2 Scene |
| brd | Cadence Allegro PCB Layout |
| brd | EAGLE PCB Layout |
| brd | KiCad Board Layout File |
| brep | Boundary Representation File |
| brf | Braille Formatted File |
| brl | BRL-CAD Document |
