according to http://help.mp3tag.de/main_tags.html, LYRICIST is currently not mapped to any WMA attribute. However, there seems to be an official attribute WM/Writer for this.
Now, I tried to map WM/Writer to LYRICIST, but that doesn't change anything. Regardless if it's mapped or not, I get the same file if I tag LYRICIST. However, if I map it differently (e.g. XXXXX to LYRICIST), I get a differing file.
So it seems like this mapping is already built-in Mp3tag. Has this been forgotten in the documentation?
One more thing. I don't know how WMA tags are internally stored/encoded in the file, it doesn't look human-readable when looking at it with a hex editor.
If I map a WMA attribute not supported by Mp3tag to another field, will it still be written according to the specification? I'd like to map WM/OriginalReleaseTime to ORIGINAL RELEASE DATE (a custom tag field I use). Or does this end up like a custom attribute, similar to the ID3v2 TXXX-frame?