M-codes location

Where are Lcnc M-codes are stored? 

I having hard time to run a custom macro in qtdragon_hd since the ini pah of subroutines not working. The macro itself is working. I also read and followed the docs on how to add multiple path to subroutines in the ini. 

Here is the part of the doc refering to custom M-codes:"The external program named M100 through M199 (no extension, a capital M, found in directory pointed by [DISPLAY] PROGRAM_PREFIX parameter of the INI file) is executed with the optional P and Q values as its two arguments."I followed this and the lcnc did not find the macro.

the txt must added to post to forum, but not used in lcnc. 

Have you set the files permission to 'Allow executing file as program'?

Now I set it. Working. Thanks.

But where are the other M codes in the system? 

The built in Mcodes (eg M2, M3, M4, M5) are hard coded in the software, if that is what you mean.

Yes, exactly what I'm looking for. Then if I need to change M6 let say, how can I do that?

M6 is one of the built-in Mcodes that can be 'remapped', Depending on the complexity of the customiziation it can be as easy as an ngc file or as complex as a python script:

linuxcnc.org/docs/2.9/html/remap/remap.h...lated_codes_t_m6_m61

[edit]

If you only require minimal changes to then start with section 5.6 in the document above.