| msd | Map Service Definition |
| mse-installer | Magic Set Editor Installer |
| msecure | mSecure Data |
| msf | Altera Mask Settings File |
| msf | Miranda IM Skin |
| msf | Mozilla Mail Folder Summary Data |
| msg5 | Microsoft Graph 5 Data |
| mshdb | Ministry Scheduler Pro Database |
| msif | MyLabel Designer Deluxe Data |
| msj | MicroSurvey CAD Temporary Data |
| msk | Affymetrix Mask File |
| msk | BrainVoyager QX Mask Data |
| 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 |
| msstyles | Windows XP Style Data |
| mst | Microsoft Windows Installer Transform |
| mst | Gurobi Optimizer MIP Start Data |
| mstat | SAM Domain Output Data |
| mstr | MicroStrategy Dashboard Data |
| msw | Modbus Slave Workspace |
| msy | MicroSyn Data |
| msz | MediaMonkey v3 Compressed Skin |
