| biot | BiotSavart Magnetic Design Data |
| bip | KeyShot Scene |
| biz | Broderbund PrintMaster Business Card |
| bjo | TabRite Tablature |
| bjt | LTspice Bipolar Design |
| bk | Adobe FrameMaker Book Document |
| bk! | Corel WordPerfect Document Backup |
| bk1 | Corel WordPerfect Document Backup |
| bk2 | Corel WordPerfect Document Backup |
| bk3 | Corel WordPerfect Document Backup |
| bk4 | Corel WordPerfect Document Backup |
| bk5 | Corel WordPerfect Document Backup |
| 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 |
| bks | Microsoft Works Spreadsheet Backup |
| bll | Binary Lasergraphics Language Document |
| blogthis | Windows Live Writer Data |
| blurb | BookWright Document |
| bmf | BrainMine Mind Map Document |
| bml | Braille2000 Braille Data |
| bmm | FX AccuCharts Market Watch 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 |
| bpf | Baan ERP Document |
| 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 |
| EAGLE PCB Layout |
| KiCad Board Layout File |
| brep | Boundary Representation File |
| brf | Braille Formatted File |
| brh | Baraha Document |
| brl | BRL-CAD Document |
| MicroBraille Document |
| brlcad | BRL-CAD Document |
| bro | PrintShop Deluxe Brochure |
| brt | Photo Builder Template |
| bry2 | Bryce 2 Scene |
| bst | BibTeX Document Style |
| bstl | StereoLithography Data |
| bt5 | ERP5 Business template |
| btab | ASCII Guitar Tab |
| btd | Business-in-a-Box Document |
| btf | Basi Office TypeFace Document |
| btx | BibTeX Document |
| btxt | BTXTPad Document |
| buz | Buzz Tools BuzzEdit Document |
| bwb | Visual Baler Spreadsheet |
| bwd | BanglaWord Document |
| bwp | BuRg3r Web Page |
| bws | SmartWare Worksheet Backup |
| bxl | Accelerated Designs Binary PCB Library |
| bxu | PictureGear Studio file |
| byd | BYP Layout Document |
| bzabw | AbiWord Bzip2 Compressed Document |
| c1d | C1Report C1D Open XML Document |
| c1dx | C1Report C1D Open XML Document |
| c2w | Cybernet v2 Document |
| c3d | Chem3D Document |
| cad | Autodesk QuickCAD Document |
