| mdcs | MATLAB Distributed Computing Server Saved Session |
| mdd | MDict Resource Data |
| mdd | Notation Composer Midi Device Description |
| mdd | Quanquest SPSS Questionnaire Definition Data |
| mdd | Xilinx Microprocessor Driver Description |
| mdef | ANSYS Workbench Managed Data |
| mdex | Mifos Data Exchange XML Data |
| mdf | Microsoft SQL Server Database |
| mdg | myPM Merge Data |
| mdif | EEsof Model MDIF File |
| mdinfo | iPhone Backup Information Data |
| mdist | PLINK Genomic Distance Proportion Matrix Data |
| mdl | Animation Master Model Data |
| mdl | Bentley MicroStation MDL Program |
| mdl | Cognos Exported Model Data |
| mdl | IBM Rational Rose Model Data |
| mdl | MDL Molfile Data |
| mdl | Rapidform Model Data |
| mdl | STAR-CD v4 Model Data |
| mdl0 | Nintendo Wii Model Data |
| mdm | BrainVoyager QX MDM Data |
| mdm | HLM Multivariate Data Matrix |
| mdm | 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 |
| 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 |
