| mt2 | MadTracker 2 Music Module |
| mt9 | ETRI MT9 Audio |
| mte | MadTracker Envelope |
| mti | MadTracker Instrument |
| mtk | MPU-401 Trakker Module |
| mtm | MultiTracker Music Module |
| mtp | MadTracker Pattern |
| mts | Music Time Pro Music |
| mts | MadTracker Sample |
| mtx | MadTracker 2 Extension |
| mu3 | Myriad Packed Musical Score |
| muk | Multak Mini 8162 Encoded Audio |
| mus | Finale Music File |
| mus | Myriad Melody Assistant Music Score |
| musa | Aleph One Music File |
| mux | Myriad Melody Assistant Stand-Alone Music Score |
| mv3 | AUPEC Encoded Audio |
| mws | IBM MWave DSP Synth Instrument Extract |
| mww | MusicWorks Data |
| mxb | Max Patcher Binary Data |
| mxl | Compressed MusicXML Notation |
| mxmf | Mobile XMF Audio |
| mxt | Max Patcher Text Data |
| mxtx | MaxTrax Music |
| myr | Myriad Melody Assistant Music Score |
| mzp | Mozart Percussion |
| n3a | Panasonic Security Camera Recorded Audio |
| nabs | Native Instruments Absynth 5 Patch |
| nap | Napster Secured Audio |
| nbs | Minecraft Note Block Studio Song |
