Why are MusicBrainz Track (Recording) IDs saved as `UFID` in MP3s while all other MusicBrainz IDs are saved as `TXXX`?

[quantenzitrone]

It has been like that since the beginning of MusicBrainz ID support
beetbox/beets@ac98777

ping @sampsyo as the original commit author on that

I stumbled over this while trying another musicbrainz/beets related tool Serene-Arc/listenbrainz-playlist-uploader#5

[quantenzitrone]

Furthermore, I think it shouldn't be named mb_trackid, as this is very confusing since the field saves the Recording ID.
MusicBrainz docs call the mb_releasetrackids just tracks: https://musicbrainz.org/doc/MusicBrainz_Identifier

[jackwilsdon]

If I had to take a guess, it's UFID as that's what Picard uses:

https://github.com/metabrainz/picard/blob/e17ecfbad066a7019a675a8b201467ed8bbbbe6a/picard/formats/id3.py#L505-L506

https://github.com/metabrainz/picard/blob/e17ecfbad066a7019a675a8b201467ed8bbbbe6a/picard/formats/id3.py#L366-L367

And this reply seems to explain why it's named mb_trackid: beetbox/beets#2690 (comment) (it sounds like MB used to call it "track id")

[quantenzitrone]

ok that makes a lot of sense

[Serene-Arc]

Seems strange that the URL it produces is malformed though, I'll need to take a look.

[quantenzitrone]

its not meant to be an url i think