| Abbreviation | Definition |
|---|---|
| LWOB | Lightwave Object Format |
| LWP | IBM Works for OS/2 Word Processor file |
| LWP | Lotus Word Pro Document |
| LYR | Song lyrics (ASCII) |
| LYT | Layout |
| LZD | Difference file for binaries (Ldiff 1.20) |
| LZH | Compressed file archive (LHA - LHARC) |
| LZS | Compressed file archive (LARC) |
| LZW | Compressed Amiga file archive (LHWarp) |
| M | Maple Common binary file |
| M | Mathematica Standard package |
| M | Matlab M-file Function and commands |
| M | Miranda programming language Script file |
| M11 | Sound (Farallon's MacRecorder format) (sampling rate 11k) |
| M11 | Text file (MASS11) |
| M1A | MPEG-1 audiostream |
| M1S | MPEG-1 systemstream |
| M1V | MPEG-1 IPB videostream |
| M2 | Modula 2 language source code file |
| M22 | Farallon's MacRecorder Sound format, sampling rate 22k |