| mjk | Adobe Illustrator Mojikumi Set |
| mjm | JMF Mime Package |
| mjs | Mijas 7400 Costing Database |
| mjx | Objectif Lune Sugopita Data |
| mk4 | Schiller Medilog ECG Raw Data File |
| mkb | DVD Audio Media Key Block |
| mkd | Pervasive SQL Database |
| mkelem | IBM Rational ClearCase MKELEM Data |
| mkg | MokkAnnotator Mokkan Glass Data |
| mkh | WinMark Pro Mark Data |
| mkl | CAD6 Library |
| mkn | PEARLNEQ MKN Input Data |
| mkr | my Knowledge Representation Data |
| mks | TACT Data File |
| mku | MagicKey Units Definition |
| mkx | Diamino Fashion Suite File |
| mla | Maple Repository File |
| mlb | HP OpenVMS Macro Library |
| mlc | Microsoft Office Language Interface Pack |
| mlc | mAirList Cart Set |
| mld | Xilinx Microprocessor Library Definition |
| mld | mAirList Desktop File |
| mle | mAirList Event List |
| mlf | Package Download Profile |
| mlg | MathsPIC Log File |
| mlg | KilnView Log Data |
| mllr | CMU Sphinx MLLR Data |
| mlml | Multi-line Markup Language Document |
| mln | Alchemy Markov Logic Network Data |
| mln | Mauve Alignment Data |
| mlog | Microsoft Outlook Message Log |
| mlp | Martus Language Pack |
| mlp | mAirList Desktop Playlist |
| mls | mAirList Script |
| mlt | mAirList Desktop Template |
