| nwc | NoteWorthy Composer Music |
| nwctxt | NoteWorthy Composer Text |
| nxt | NeXTSTEP Sound File |
| o01 | Typhoon Voice Data |
| obw | Superior Drummer Sound File |
| ocdf | OneClickDigital Audio Book |
| odd | Coby Voice Recorder Data |
| ofg | OptimFROG Dualstream Audio |
| ofr | OptimFROG Lossless Audio |
| oga | Ogg Vorbis Compressed Audio |
| ogg | Ogg Vorbis Compressed Audio |
| ogx | Ogg Vorbis Compressed Audio |
| okt | Oktalyzer Music Module |
| olv | OnLive! Traveler Sound |
| oma | Sony ATRAC3 Compressed Audio |
| omg | Sony OpenMG Audio |
| omg | Sony ATRAC3 Compressed Audio |
| oml | OtsAV Media Library |
| omx | OtsAV Media Library Information |
| opm | FM Operator Type-M Voice Data |
| opu | Opus Audio File |
| opus | Opus Audio File |
| orc | Voyetra Digital Orchestrator Pro Song |
| ots | OtsAV Album |
| p4x | The Player 4.x Music |
| p50 | The Player 5.0a Module |
| paal | Cakewalk Pyro Audio Creator Audio Layout |
| pac | SBStudio II Song Package |
| pca | Sony Perfect Clarity Audio |
| pcg | Korg Trinity Instrument Bank |
