| bmu | Bioware Aurora Music Unit |
| bmz | Portal Bonus Map Zip |
| bni | Battle.net Icon File |
| bnry | The Sims 4 Game Data |
| bnt | Entropia Universe Game Archive |
| bo2 | TerrainControl Custom Biome Objects v2 |
| bo3 | TerrainControl Custom Biome Objects v3 |
| bod | X3: Reunion Ship Data |
| bol | Mario Kart Wii Course Setup |
| bos | Fallout Tactics: Brotherhood of Steel Data |
| bot | Quake FrogBot Data |
| bpe | WWE Texture Archive |
| brasd | Mario Kart Binary Revolution Animation Sound Data |
| brmdl | Mario Kart Wii 3D Model Data |
| brseq | Binary Revolution Sequence Data |
| brtex | Mario Kart Wii Texture Data |
| brz | Combat Mission: Shock Force Archive |
| bs1 | VirtualBus Vehicle Configuration |
| bsa | Fallout 3 Bethesda Softworks Archive |
| bsg | Besiege Machine |
| bsm | Bioshock Map Data |
| bsp | Quake Map Data |
| bspec | SimCity 4 Bridge Specs Data |
| bspr | Need for Speed: Shift Track Map |
| bss | Resident Evil Background Image |
| btb | Warhammer: Dark Omen Map |
| btg | Binary TerraGear Data |
| btl | American Civil War Battle Data |
| bts | Combat Mission Shock Force Saved Scenario |
| btt | Combat Mission Shock Force Scenario |
| bty | Railroad Tycoon 3 Game Data |
| bun | The Dig Game Data |
| bus | VirtualBus Board Parameters File |
| bwd | Colin McRae Rally 2 Car Description File |
| bwe | Black and White 2 Environment Data |