Sorry, either my search-capacities are not very good or there simply is not yet a definite answer to my question ...
My problem is with the tag for Album Artist: not for MP3 (the "Band" tag writes to TPE2 and that is read correct by most players), but with FLAC.
MP3tag creates a tag with the fieldname "Band" in the FLAC file and that is not read by Winamp. Winamp expects "Album Artist" (with space) or "albumartist". On the other hand, if I set MP3tag to write to Album Artist instead of Band, it is not read correctly in MP3. So that is not an option, apparently two different fields with the same content are needed for either MP3 or FLAC.
I know that I can manually copy the contents of "Band" into the fields "Album Artist" and "albumartist" via Format Value, but my problem is that that means that I always have to think of doing that, after tagging the FLACs.
So I have searched for an option to have MP3tag write automatically to 2 or 3 fields when tagging something in the "Band" column when the file at hand is a FLAC file, but could not find it.
Did I miss something and is this possible in MP3tag?
Or is there perhaps any other way of automating this, that I have overlooked?