Which var is needed to have all files I want to burn added to command line? I need full path in quotes and each file seperated by a space.
Example: CDBurnerXPcmd.exe --burn-data device:1 files:"MP3\Test1.mp3" "MP3\Test2.mp3" "MP3\Test3.mp3" ...
{allfilepath$} is what you want. It will automatically quote any paths with spaces (but doesn't quote ones without spaces).
From a quick test it looks like Opus always ensures there is a space before the first filename generated by {allfilepath$} so if the program requires that there is no space between the files: and the first name then you may run into problems.
Ok, I was right. When trying this the program crashes. Other options don't work.
Does CDBurnerXPcmd.exe still crash if you run it manually with the command you're expecting Opus to generate?
No, when adding files manually or manually with "-folder:" option it works. Other vars are ignored (just burns an empty cd then; using a CD-RW of course 
).
Surely I could use Nero, but CDBurnerXP is free and small.
Does it crash if you add the space after the -folder: ? That should be the only difference.
You could use doptest.exe from the Tools area to see the exact command line that Opus is running.
It crashes if more than one file or folder is selected (option "-file" or "-folder"). Space between option and path doesn't have any effect.
But also when selecting one file or folder it will burn an empty disc without files.
Using -folder:"%1" will burn each folder incl. all files seperately, using -file:"%1" same each file.
Burning all selected files is the method I would prefer.
Sounds like something to ask the CDBurnerXP authors as there's not much Opus can do to workaround CDBurnerXP's crash/bug, unless I've misunderstood the problem.
I tried burning selected files with Nero (NerOpus). Also I get lots of error messages because of invalid filenames. When burning complete folder (where incorrect named files are included) no errors occurs. So may {allfilepath$} is not working correct?
I doubt it's {allfilepath$} as I looked at what it generated while testing my first reply and it's used by lots of people in lots of buttons.
Have you looked at the command-line that Opus is generating (e.g. using the doptest program in the Tools forum) to check that it's what you expect? If it looks right, try running Nero manually with the same command-line and see what happens.
Tested a lot now...
NerOpus does have problems on some vars in Nero 8. The disc-name-parameter doesn't work after more than one file has been selected.
Maybe I will post an updated NerOpus.dop after removing all errors.
I remember some changes were needed with the upgrade from Nero 6 to 7. I guess they've changed their command line yet again. 