| mrec | MADRIX Record File |
| mres | ANSYS DesignModeler Results Data |
| mrf | Mapped Read Format Data |
| mrf | MultiEx Commander Resource Data |
| mrg | DESQview MRG Data |
| mrg | Microsoft Windows Installer Merge Data |
| mrg | MySQL Merge File |
| mri | Pittsburgh MRI File Format Data |
| mrk | GP-Pro EX Mark Library |
| mrk | Kodak EasyShare Job Definition |
| mrk | Pro/ENGINEER Markup File |
| mrm | CloseToSoftware MacroRunner Macro |
| mrp | Xilinx MAP Report |
| mrpd | IBM TS3500 Machine Reported Product Data |
| mrq | NETFILE Tax Data |
| mrs | Corel WordPerfect Macro Resource |
| mrsl | THOR Metadata Rich Spectral Library Data |
| mrt | Stimulsoft Report |
| mrv | Marvin Document Format File |
| mrx | Malete Record Access File |
| mry | Mercury Binary Crystal Data |
| mryx | Mercury Compressed XML Crystal Data |
| ms | Autodesk 3D Studio Max Script |
| ms-tnef | MS Transport Neutral Encapsulation Format |
| ms1 | Crux MS/MS Data |
| ms2 | Crux MS/MS Data |
| ms2 | MADRIX Setup Data |
| ms2 | SEQUEST MS2 Format Data |
| ms4 | MAILERS+4 Index Data |
| msbcm | Microsoft Office Business Contact Manager Backup Data |
