| mrp | Xilinx MAP Report |
| mrpd | IBM TS3500 Machine Reported Product Data |
| mrt | Stimulsoft Report |
| mrv | Marvin Document Format File |
| mrx | Malete Record Access File |
| ms | Autodesk 3D Studio Max Script |
| ms-tnef | MS Transport Neutral Encapsulation Format |
| ms1 | Crux MS/MS Data |
| ms2 | Crux MS/MS Data |
| ms4 | MAILERS+4 Index Data |
| msbcm | Microsoft Office Business Contact Manager Backup Data |
| mscc | mSecure Data |
| mscml | Media Server Control Markup Language File |
| mscx | mSecure Backup |
| msd | Map Service Definition |
| mse-installer | Magic Set Editor Installer |
| msecure | mSecure Data |
| msf | Miranda IM Skin |
| msf | Altera Mask Settings File |
| msf | Mozilla Mail Folder Summary Data |
| msg5 | Microsoft Graph 5 Data |
| mshdb | Ministry Scheduler Pro Database |
| msif | MyLabel Designer Deluxe Data |
| msk | BrainVoyager QX Mask Data |
| msk | Affymetrix Mask File |
| mskin | Maxthon Browser Skin |
| mskn | MediaMonkey Skin |
| mso | Microsoft Office Rendering Data |
| msor | FiberTrace Data |
| mspdi | Microsoft Project XML Data Interchange File |
| mspm | Nanoeducator File |
| msq | LightShow Pro Media Sequence |
| msr | Mail.dat Manifest Summary File |
| mss | Microprocessor Software Specification |
| msstyle | Windows XP Unsigned Style |