work name, name and movement

iTunes version 12.5.1.21 is writing "work name, name and movement" in audio files.

sample captured in mediainfo
©wrk : Work
©mvn : Work Name
©mvi : 2
©mvc : 3

Apple says : "Tag for movement name is 'MVNM' and movement number is 'MVIN’".

I have seen this in m4a, I suspect it is the same for mp3.

Please check this and update in mp3tag.

Please support these new fields

Somebody please respond.

The field "work" appears as "contentgroup" in MP3tag.

I just found that out when I entered some arbitrary data in iTunes "Work", modified the tag version of the file and then checked which field appeared in MP3tag.
Perhaps you can do the same for the other fields you are missing.

Florian made some addions:
[2016-11-15] NEW: added support for iTunes tag fields for classical music MOVEMENT, MOVEMENTTOTAL, MOVEMENTNAME (ID3v2 and MP4) and for WORK (MP4 only).

Could someone explain the use of those new fields. I know what a MOVEMENT is, but, I'm not sure about the use of the new tag fields.