| 1. | M | Function and commands (Matlab M-file/Mathematica) Common binary file name extension (Maple) Macro module (Brief) Objective-C language source code file (gcc) Script file (Miranda programming language) Standard package (Mathematica) |
| 2. | M11 | Sound (Farallon's MacRecorder format) (sampling rate 11k) Text file (MASS11) |
| 3. | M1A | |
| 4. | M1S | |
| 5. | M1V | Moving Pictures Experts Group video (MPEG-1 IPB) |
| 6. | M2 | Modula 2 language source code file |
| 7. | M22 | Sound (Farallon's MacRecorder format) (sampling rate 22k) |
| 8. | M2A | |
| 9. | M2V | |
| 10. | M3 | Modula3 language source code file |
| 11. | M3A | |
| 12. | M3D | Corel MOTION 3D Scene movie |
| 13. | M3U | |
| 14. | M4 | M4 preprocessor file (unix) |
| 15. | M7 | Sound (Farallon's MacRecorder format) (sampling rate 7k) |
| 16. | MA | Ascii file (notebook) (Mathematica) hDC products for MicroApp executable files |
| 17. | MA3 | Harvard Graphics 3.0 macro |
| 18. | MAC | MacPaint bitmap image, black & white, PackBits compressed. Also .PNT and .PNTG are used for this format MACro file Assembly Language file |
| 19. | MACP | Apple Macintosh MacPaint bitmap image |
| 20. | MAD | Ms Access Module Shortcut |