[BatterPudding]

But of course that does not mean contributors have not put "Disc 1" in there sometimes.

Big loud TICK here. Users at MB shouldn't put "disc 1" or "CD 1", but some do. As a MB editor myself, when I have seen that kind of daftness, I'll delete it everytime. But there are always some who ignore guidelines.

Split album when DISCSUBTITLE is not null

One advantage of this is it means someone can stop a Release being split by blanking their DISCSUBTITLE. I do like the look of the rest of those options.



I have a few examples I can pull out of my own collection that are variations on a theme. Including some of the "don't be bloody awkward" ones. 
(ARGH!  This FSCKING STUPID Forum just lost a complex reply.   These stupid lookup things that the browser keeps trying to do killed the reply.  Attempting to retype it but have lost the details now )

The Sisters of Mercy - Original Album Series
https://musicbrainz.org/release/85c8f5ad...63a7b2a09b
5xCD
This is a "simple" one.  Just five separate back catalogue releases in one card sleeve.  Each are identical to the original CD release.  These discs could just be catalogued on their own as the boxset sleeve doesn't bring anything new.  I currently have these in my KODI as the five separate albums tagged with separate MBIDs to avoid the "play all" issue.

Peter Gabriel - So (25th Anniversary Deluxe Boxset)
https://musicbrainz.org/release/17cbddd3...151a905017
4×CD + 2×DVD-Video + 2×12" Vinyl
These are getting more and more common.  Anniversary cash-in releases with heaps of added extras.  Most of the time I only want to listen to the first disk.  Currently when I hit "Play" in KODI it chunders through all of this.  Most of the content of the extra discs are "interesting curios".

This is sitting in my KODI collection alongside the original CD release of the album.

Pink Floyd - Discovery Boxset
https://musicbrainz.org/release/e2d8bb4d...8f1495d6ae
16×CD
Fourteen separate albums with no connection to the next.  This is just a whole back catalogue discography.  Though watch out as there are two double albums in there. The Wall will cause trouble here as some awkward user will want that treated as a pair (I'd tell them to "Get Stuffed" as this is complex enough as it is ) 

This is another one of those cases where I own many of these albums individually, sometimes multiple editions.

Pink Floyd - The Early Years
https://musicbrainz.org/release/220fbaf4...d75a7391e3
11×CD + 9×DVD-Video + 8×Blu-ray + 5×7" Vinyl
Yeah - a boxset of boxsets.  Or how to give the Devs an even bigger headache as we disappear further down the rabbit hole.


Some random thoughts:

* Maybe an initial hack would be to treat the MBID+DISCSUBTITLE as some kind of unique combo.  Would be nice to see these titled as "Boxset Title : DiscSubtitle" in the GUI listed with the albums.  A five part boxset becomes five albums in that list.  (Or TITLE : DISC NO : DISCSUBTITLE to make sure discs are listed in order)

* Most boxsets have separate art for the separate disks.  Sometimes separate covers too.  The newer the release, the more likely you'll see a ton of artwork at MB.  (Just look at the huge heap of Art for the Floyd Boxsets!)