| wv | WavPack Audio |
| wvc | Wavecraft Audio |
| wve | Psion 8-bit A-law Audio |
| wvz | MUST Music |
| wwv | WildTangent WAV Audio |
| wyz | WYZTracker Song |
| x-ape | JRiver Media Center APE Audio |
| x0a | Yamaha Motif XS Song Data |
| x0e | Yamaha Motif XS Editor File |
| x0p | Yamaha Motif XS Pattern Data |
| x0s | Yamaha Motif XS Song Data |
| x0v | Yamaha Motif XS Voice Data |
| x3a | Yamaha Motif XF Song Data |
| x3v | Yamaha Motif XF Voice Data |
| x3w | Yamaha Motif XF Waveform Data |
| x4a | Yamaha MOX6 All Audio Data |
| x4e | Yamaha MOX6 Editor Audio |
| x4v | Yamaha MOX6 Voice Data |
| x5a | Yamaha MX49 Library Data |
| x6v | Yamaha MOXF Voice Data |
| xad | eXotic ADlib Audio |
| xan | XANN Packer Audio Data |
| xann | XANN Packer Audio Data |
| xfs | eRacer Sound |
| xgc | Binary eXtended Genesis Music |
| xgm | eXtended Genesis Music |
| xi | FastTracker 2 Instrument |
| xiz | ZynAddSubFX Instrument File |
| xkr | Sing-Magic Karaoke Song |
| xm | FastTracker 2 Music Module |
