| msk | CARA Script Engine Mask |
| mskin | Maxthon Browser Skin |
| mskn | MediaMonkey Skin |
| msl | ImageMagick Script Language Data |
| msl | Miranda IM Smiley Definitions Data |
| msmpl_all | Korg microSAMPLER Backup Data |
| msmt | WNCS Measurement Data |
| msnbak | MSN Mail Backup Data |
| mso | Microsoft Office Rendering Data |
| msof | Microsoft Office for Mac Data |
| msor | FiberTrace Data |
| mspdi | Microsoft Project XML Data Interchange File |
| mspj | Microsoft Project for Mac Data |
| mspm | Nanoeducator File |
| msq | LightShow Pro Media Sequence |
| msr | Mail.dat Manifest Summary File |
| mss | Microprocessor Software Specification |
| mss | WRAP Message Data |
| mssp | mIRC Script Setup Creator Data |
| msstyle | Windows XP Unsigned Style |
| msstyles | Windows XP Style Data |
| mst | Gurobi Optimizer MIP Start Data |
| mst | Microsoft Windows Installer Transform |
| mstat | SAM Domain Output Data |
| mstr | MicroStrategy Dashboard Data |
| mstt | Prosa Minispecification Data |
| mstxt | Message Studio Text Data |
| msty | Muvee Automatic Video Editing Style |
| msvp | eXtendable Wad Editor MSVP Data |
| msw | Modbus Slave Workspace |
| mswallet | Microsoft Wallet Item Package |
| msxml | Mercury Motif Searches Data |
| msy | MicroSyn Data |
| msz | MediaMonkey v3 Compressed Skin |
| mt5 | Poser Material Data |
