See https://picard.musicbrainz.org/docs/mappings/

This tag is useful when the user would like all releases of the same
album to be sorted next to each other.

Drop support for misencoded tags.  People should not be using ID3v1
anyway.

The new tag is supported by all decoders that use the tag name table,
and the ID3v2 tag "TSOA" maps to it.

The Release Track Id uniquely identifies a recording on a release - that
is, even if a recording appears twice on a release (meaning that the
combination of recording and release id are not enough to figure out
which one it is), the release track id will allow differentiating the two.

The tag names are taken from
https://musicbrainz.org/doc/MusicBrainz_Picard/Tags/Mapping

Replaces g_strstrip().