| mmr | Sybase PowerDesigner Multimodel Report |
| mmt | Nimbus 7 SAMS MMRVT Data |
| mmu | myPM Merge Data |
| mmw | Microsoft Office Clip Organizer Catalog |
| mmysyscache | Milennial Media Ad Cache |
| mn1 | Microsoft Money v1 Data |
| mn4 | Microsoft Money 95 Data |
| mn6 | Microsoft Money 98 Data |
| mn7 | Microsoft Money 99 Data |
| mn8 | Microsoft Money 8 Data |
| mnc | Autodesk AutoCAD Compiled Menu |
| mnd | Fractal Forge v2 Fractal Parameters |
| mnf | MSC Adams Model Neutral Data |
| mni | Cerious Mandelbrot Image |
| mnit | SlimBrowser MNIT Data |
| mnk | My Notes Keeper Notebook |
| mnm | Autodesk Character Studio Marker Name |
| mnn | Microsoft Money Cache Data |
| mnr | Autodesk AutoCAD Menu Resource |
| mns | Autodesk AutoCAD Menu Source |
| mnu | Autodesk AutoCAD Menu Definition |
| mnu | General CADD Menu |
| mnu | SmartWare Menu Keywords Data |
| mo1 | Magnavox Odyssey 1 Emulator ROM Image |
| moa | MOA Data File |
| mob | MobTV P2P File |
| moba | MobaXterm Data |
| moc3 | Live2D Cubism 3 Model Data |
| mod | ArchiCAD Module File |
| mode | Coda Syntax Mode |
| model | Ribbons Model Definition |
| modfem | Femap Model File |
| moe | Molecular Operating Environment File |
| moef | Motion Effect Template |
| mogrt | Adobe Premiere Motion Graphics Template |