| mcz | Poser Compressed Material Collection |
| md | Chaos Desktop Metadata |
| md | Sega Genesis ROM MD |
| md | Sharkport Saved Game |
| md | Technics SX-KN6000 User MIDI Settings Data |
| md0 | Adobe Photoshop Metadata Cache |
| md03 | Macromedia Director Data |
| md2p | MessengerDiscovery M2DP Data |
| md2s | MessengerDiscovery Data |
| md5 | MD5 Checksum |
| md5sum | MD5 Checksum |
| md5sums | MD5 Checksum |
| md93 | Macromedia Director 4 Data |
| md95 | Adobe Director for Mac Data |
| mdat | REW Measurement Data |
| mdb | Nastran Modal Database |
| mdb | RockWorks Borehole Database |
| mdbx | Microsoft Access JET Database |
| mdc | Cognos Cube File |
| mdccache | Microsoft Document Connection Cache Data |
| mdcs | MATLAB Distributed Computing Server Saved Session |
| mdd | BSL MDD Data |
| mdd | MDict Resource Data |
| mdd | Notation Composer Midi Device Description |
| mdd | Point Oven Deformation Data |
| mdd | Quanquest SPSS Questionnaire Definition Data |
| mdd | Xilinx Microprocessor Driver Description |
| mde | ArchiCAD Education Module File |
| mdef | ANSYS Workbench Managed Data |
| mdex | Mifos Data Exchange XML Data |
