| Extension | File Description |
| .BOOT0 | Uncommon Files |
| .BOOTSCREEN | Uncommon Files |
| .BOOTSKIN | Misc Files |
| .BOP | Uncommon Files |
| .BOQ | Uncommon Files |
| .BOR | Uncommon Files |
| .BORDERS | Uncommon Files |
| .BORED | Uncommon Files |
| .BORLAND | Uncommon Files |
| .BOS | Uncommon Files |
| .BOSSFONT | Uncommon Files |
| .BOT | Uncommon Files |
| .BOU | Uncommon Files |
| .BOULDER | Uncommon Files |
| .BOULESHP | Uncommon Files |
| .BOUTON | Uncommon Files |
| .BOV | Uncommon Files |
| .BOW | Uncommon Files |
| .BOWL | Uncommon Files |
| .BOX | Video Files |
| .BOX3D | Uncommon Files |
| .BOXES | Uncommon Files |
| .BOXR | Uncommon Files |
| .BOY | Uncommon Files |
| .BOZ | Uncommon Files |
| .BP | Uncommon Files |
| .BP0 | Uncommon Files |
| .BP1 | Uncommon Files |
| .BP2 | Uncommon Files |
| .BP3 | Uncommon Files |
| .BP4 | Uncommon Files |
| .BP5 | Uncommon Files |
| .BP6 | Uncommon Files |
| .BP7 | Uncommon Files |
| .BP8 | Uncommon Files |
| .BP9 | Uncommon Files |
| .BPA | Backup Files |
| .BPB | Uncommon Files |
| .BPC | Uncommon Files |
| .BPD | Uncommon Files |
| .BPDX | Uncommon Files |
| .BPE | Uncommon Files |
| .BPEL | Uncommon Files |
| .BPF | Uncommon Files |
| .BPG | Developer Files |
| .BPH | Uncommon Files |
| .BPI | Uncommon Files |
| .BPJ | Uncommon Files |
| .BPK | Encoded Files |
| .BPKEY | Uncommon Files |
| .BPL | Developer Files |
| .BPLIB | Uncommon Files |
| .BPM | Backup Files |
| .BPMN | Uncommon Files |
| .BPN | Uncommon Files |
| .BPO | Uncommon Files |
| .BPP | Uncommon Files |
| .BPQ | Uncommon Files |
| .BPR | Uncommon Files |
| .BPS | Backup Files |
| .BPT | Uncommon Files |
| .BPU | Uncommon Files |
| .BPV | Uncommon Files |
| .BPW | Uncommon Files |
| .BPX | Uncommon Files |
| .BPY | Uncommon Files |
| .BPZ | Uncommon Files |
| .BQ0 | Uncommon Files |
| .BQ1 | Uncommon Files |
| .BQ2 | Uncommon Files |
| .BQ3 | Uncommon Files |
| .BQ4 | Uncommon Files |
| .BQ5 | Uncommon Files |
| .BQ6 | Uncommon Files |
| .BQ7 | Uncommon Files |
| Extension | File Description |
| .BQ8 | Uncommon Files |
| .BQ9 | Uncommon Files |
| .BQA | Uncommon Files |
| .BQB | Uncommon Files |
| .BQC | Uncommon Files |
| .BQD | Uncommon Files |
| .BQE | Uncommon Files |
| .BQF | Uncommon Files |
| .BQG | Uncommon Files |
| .BQH | Uncommon Files |
| .BQI | Uncommon Files |
| .BQJ | Uncommon Files |
| .BQK | Uncommon Files |
| .BQL | Uncommon Files |
| .BQM | Uncommon Files |
| .BQN | Uncommon Files |
| .BQO | Uncommon Files |
| .BQP | Uncommon Files |
| .BQQ | Uncommon Files |
| .BQR | Uncommon Files |
| .BQS | Uncommon Files |
| .BQT | Uncommon Files |
| .BQU | Uncommon Files |
| .BQV | Uncommon Files |
| .BQW | Uncommon Files |
| .BQX | Uncommon Files |
| .BQY | Uncommon Files |
| .BQZ | Uncommon Files |
| .BR | Uncommon Files |
| .BR0 | Uncommon Files |
| .BR1 | Uncommon Files |
| .BR2 | Uncommon Files |
| .BR3 | 3D Image Files |
| .BR4 | 3D Image Files |
| .BR5 | 3D Image Files |
| .BR6 | 3D Image Files |
| .BR7 | Uncommon Files |
| .BR8 | Uncommon Files |
| .BR9 | Uncommon Files |
| .BRA | Uncommon Files |
| .BRAIN | Data Files |
| .BRAINCHIME | Uncommon Files |
| .BRAS | Uncommon Files |
| .BRB | Uncommon Files |
| .BRC | Uncommon Files |
| .BRCC | Uncommon Files |
| .BRD | Data Files |
| .BRE | Uncommon Files |
| .BREAK | Uncommon Files |
| .BREAST | Uncommon Files |
| .BREATH | Uncommon Files |
| .BREP | Uncommon Files |
| .BRF | Uncommon Files |
| .BRG | Uncommon Files |
| .BRH | Uncommon Files |
| .BRI | Plugin Files |
| .BRIDGESORT | Uncommon Files |
| .BRITANNIA | Uncommon Files |
| .BRJ | Uncommon Files |
| .BRK | Raster Image Files |
| .BRL | Uncommon Files |
| .BRLCAD | Uncommon Files |
| .BRM | Plugin Files |
| .BRN | Game Files |
| .BRO | Page Layout Files |
| .BRP | Uncommon Files |
| .BRQ | Uncommon Files |
| .BRR | Uncommon Files |
| .BRS | Uncommon Files |
| .BRSH | Uncommon Files |
| .BRSTM | Audio Files |
| .BRT | Raster Image Files |
| .BRU | Uncommon Files |
| .BRUSH | Uncommon Files |
| .BRUSH2 | Uncommon Files |
