| mxrw | Mandelbrot Explorer RAW Data |
| mxs | ArcVIEW Geocode ODB Index |
| mxs | Carlson 2016 Multiple Cross Sections Data |
| mxs | Corel Painter Mixer Pad Data |
| mxsd | IBM WebSphere Message Definition Data |
| mxskin | Maxthon Browser Skin |
| mxt | ArcMAP Template |
| mxt | Fortran 5 Data File |
| mxz | Maximizer CRM Data |
| my3d | Hasbro My3D File |
| myb | MYOB AccountRight Company Data |
| mybible | MySword Bible Database |
| mycolors | Stardock MyColors Theme |
| myd | MySQL MyISAM Table Data |
| mye | MYOB AccountEdge Exported Data |
| myfourwalls | MyFourWalls Room Model |
| myi | MySQL MyISAM Table Index Data |
| mylic | MySpeed License Key |
| mym | Mymenuify Theme Data |
| mynotesbackup | Keep My Notes Backup Data |
| myo | MYOB AccountRight Company Data |
| myob | MYOB AccountRight Company Data |
| myox | MYOB AccountRight 2011 Company Data |
| mysql | SQL Script |
| mysqli | MySQL Native Driver for PHP Data |
| mz2 | Maze-Solver Data |
| mz5 | Poser 5 Binary Material Data |
| mzd | Mozy Restore Definition Data |
| mze | Maze Creator Maze Data |
| mzxml | SPC mzXML Data |
