I am using MusicBee, and that by default uses vorbis tags such as ORIGALBUM, ORIGARTIST, ORIGYEAR etc. for this.
That probably originated from it being compatible with MP3tag, that does the same.
But of course there is no agreed standard on this, so it’s probably impossible to make everybody happy.
And it’s not very difficult to make some changes in a MusicBee configuration file for that, but it’s just that I am hoping to get everything working ‘out-of-the-box’ as much as possible with as less as possible scripts, formulas, changing of .ini and config files etc.
And I also asked because this is all some learning process for me.
Since documentation about these functions is quite sparse, I was curious after I found out about “$set(_id3:” if there was perhaps the same functionality for vorbis/flac.
Probably not 
.
That would be a good solution and I had tried something like that, but couldn’t get it working.
I tried these three syntaxes:
$set(_id3:TXXX/ORIGALBUM,)
$set(_id3:TXXX:ORIGALBUM,)
$set(_id3:ORIGALBUM,)
Am I doing something wrong here?