| mdl | ASTi Model Builder Model Data |
| Bentley MicroStation MDL Program |
| Cognos Exported Model Data |
| DB-MAIN Method Definition Data |
| IBM Rational Rose Model Data |
| Leadwerks 3D Model |
| Lectra Clothing Design Model |
| MapShots Model Data |
| MDL Molfile Data |
| Mighty Draw DOS Library |
| Moray 3D Model |
| Rapidform Model Data |
| STAR-CD v4 Model Data |
| Symbian OS MIME Type Library |
| Vensim Model |
| mdl0 | Nintendo Wii Model Data |
| mdm | BrainVoyager QX MDM Data |
| HLM Multivariate Data Matrix |
| OvenWATCH Dataset |
| mdn | Microsoft Access Blank Database Template |
| mdo | Microsoft IIS Metabase Backup |
| mdp | GROMACS Molecular Dynamics Program |
| mdpd | Trajexia Saved Parameters Data |
| mdq | Database Interface Designer Database Query Data |
| Transformation Extender Database Definition Data |
| mdr | ZX Spectrum Emulator Microdrive Cartridge Data |
| mds | PLINK Multidimensional Scaling Report Data |
| mdsx | MEGA Saved Session |
| mdtext | Markdown Text Data |
| mdtxt | Markdown Text Data |
| mdu | D-Flow FM Model Definition Unstructured Data |
| mdus | MessengerDiscovery Internal Data |
| mdv | SmartWare Modem Definition Data |
| mdw | Microsoft Access Workgroup Data |
| mdx | dBASE IV Multiple Index |
| MDict Dictionary Data |
| mdy | Sprint RSS iDEN Contact List Data |
| me | Kodak EasyShare Thumbnail Cache |
| Multi-Edit Configuration |
| mea | Marvelous Designer Tape Measure Data |
| Mastersizer 2000 Data |
| Meazure Data |
| meb | Corel WordPerfect ME Bottom Overflow Data |
| PRO100 3D Interior Catalog Element |
| mechdat | ANSYS Mechanical Exported Data |
| mechdb | ANSYS Mechanical Database |
| mecontact | Live Messenger Contacts Data |
| med | A2B Player Purchase Data |
| Corel WordPerfect Macro Editor Data |
| MOBILedit Phone Image Data |
| mediaget2 | MediaGet Data |
| mef | Jaws PDF Server Exported Settings |
| mefp | ExerciseRT Sample Data Record |
| mefs | ExerciseRT Secondary Data Record |
| meg | MEGA Data |
| mega | Megacubo XML Metafile |
| megamanager | Mega Manager Data |
| meh | Adobe Acrobat Language Resource Data |
| mem | BPM Studio Sampler Functions Data |
| E-Sword v8 Memory Verses Data |
| GreekToMe Memories Data |
| Medical Expense Manager Data |
| Medlin Payroll Software Additional Vendor Data |
| Mnemosyne Card Collection |
| Parallels Desktop Memory Dump |
| Virtual Game Station Memory Card |
| memb | PTC Creo Assembly Member Information Data |
| meme | MEME Motif Format Data |
| memo | S Memo Data |
| memx | E-Sword v9 Memory Verses Data |
| men | Cabri II Plus Menu Data |
| menc | Windows Mobile Encrypted File |
| menu | macOS SystemUIServer MenuExtra Plugin |
| Steam Client GUI Menu Data |
| Zoom Player Menu Text Data |
| menuskin | ObjectBar Menu Skin |
| mep | Inor MePro Data |
| meps | MEPS Data |
| meq | Corel WordPerfect Macro Editor Print Queue |
| mer | Corel WordPerfect Macro Editor Resident Area |
