@ZungryWare has compiled an exhaustive list of hacks here:

https://scalar.vector.im/etherpad/p/r.6ad54765f5b9b714d4501dbb1b728c7f 

Thanks everyone for the help & support. 

also if you haven't seen it yet, there is a whole long-running thread about map hacks:

Teaching Old Progs.dat New Tricks 

I think I've found all necessary functions in the progs and definitions.
I will try to copy and paste after the weekend and tell if it works. 

I tried and failed.
Seems I've got to read more into detail. 

I will take a look this evening. (I said that before but forgot.)

I will report back here. Adding a reminder on my phone for after work. 

I was able to get a CD track to play using the built-in command SVC_CDTRACK

I have a killable Chthon and added this to the end of the function where he gibs.

WriteByte (MSG_ALL, SVC_CDTRACK);
WriteByte (MSG_ALL, 3);
WriteByte (MSG_ALL, 3);

Track 3 played perfectly from my music directory.

You need to repeat the 2nd command for it to work. In Quakespasm I got developer errors about not finding the CD track but that is only in dev mode and the music still plays. If you need further help I would need to see what you are coding.

As far as using the AD functions, that's a bit too much work for me and I am not sure I could get it to work properly. Try the built-in id function first. 

Thank a lot!

i was able to find the code for cdtrack in the targets.qc and built it in the progs.dat but finaly struggled, from my point of view, with the definition of the functions.

I*m looking forward to check the SVC_cdtrack this week and tell you if it works.

best wishes. 

WriteByte (MSG_ALL, SVC_CDTRACK);
WriteByte (MSG_ALL, 3);
WriteByte (MSG_ALL, 3);

Track 3 played perfectly from my music directory.

You need to repeat the 2nd command for it to work.

The second writebyte is setting a variable called cl.looptrack - which on first glance you would expect would control whether the track loops or not. Surprise! It's not actually implemented in the engine, so the track always loops. You are free to send any number in the second WriteByte, it doesn't need to be the same as the track number.

If you'd like to play a CD track without it looping, the alternative is to use stuffcmd with the console command "cd play 3". You can also replicate the looping cd track from the SVC_ command with "cd loop 3". 

Ok, I thought the whole thing over and came to the conclusion that whatever I will do, I have to make it a trigger_cdtrack. Otherwise it will not work with the mod.
That means getting into the whole qc-thing and read a lot.
So at this point I will finish mapping first before doing anything else.
Thanks to dumptruck_ds and preach for the assistance!
Hope I can ask you again when the job is done.

best wishes 

One last thought: If the mod you're using has the equivalent of
trigger_command then you can use the console command to achieve what you're after without modifying it. 

I looked at the code again and wondered why my attemp doesn't work.
I copied the trigger_cdtrack function (is equal to the code dumptruck_ds showed with a -change and -use procedure) from AD's target.qc to my progs_dump/triggers.qc next to the trigger_relay function and compiled the progs.dat.
Then I copied the trigger_cdtrack definition from AD's .fgd to my progs_dump.fgd with the windows editor.
When I entered Trenchbroom and changed to the new fgd (in new progs_dump folder with the changed progs.dat) I got this message: "progs_dump_112.fgd': At line 1, column 1: Unknown entity definition class '//'".
I think I'm not to far from a solution.
Have I missed to change or add something in the progs or done a failur in the fgd? 

looks like invalid characters in the fgd 

Yeah, if you encode the sequence "" in the default windows codeset and decode that as UTF8 you get character FEFF (a byte order mark). Working backwards I guess the program you used to edit the fgd saved the file as UTF-8 and added a byte order mark. Trenchbroom is then opening the file as 8-bit windows codeset text and seeing garbage at the top. Suggest you reopen the cfg file and save it in ascii format, which should get rid of the garbage. 

It should have been saved in ANSI.
I will try to save in Unicode and use notepad if it doesn't work. 

So. This challange is masterd.
For no reasons, the widows editor saves automaticly in UTF-8. So I changed that in ANSI and now theres a trigger_cdtrack in trenchbroom.:)
That's the good news.
The other is that I was wrong about the compiling.

Whatever progs.dat I decompile and recompile ,with fteqccgui64, I get messages like this:"defs.qc:328: error: "ev_field" is not a type in function SUB_CalcMove (line 61), subs.qc:66: error: Unknown value "tspeed"Errors have occured Error in defs.qc on line 328."
The funny thing is that fteqcc shows erros, but
the progs work.

I have absolutly no idea what happens here. 

Built from the source. Now it works. 

how check max entities limin in trenchbroom? 

Please can someone help me I tried to convert a .bsp2 map to .bsp1 for a game that uses the Quake 1 Engine, but it gives me error ModLoadBrushModel has wrong version number .... should be 29, how can I solve? 

Hi.
Yesterday I got a fascinating problem.
Got the message Alloc Block: full and started to solve the problem like usual.

replaced every bad texture. -nothing
deleted or repaired every unclean brush. - nothing
deleted over 60 lights. -nothing
deleted all trenchbroom autosaves. -nothing
deleted all the maps .bsp, .lit, config,... and recompiled the map. -nothing

Sollution:
Deleted Quakespasm and reinstalled. No Error anymore.

Has anyone an idea what happend?
I think this would be usefull to everyone.

best wishes