Release groups usage guideline

The latest (2009-05-24) MusicBrainz server release features a concept called "release groups". Just as the name suggests, it groups several releases together under one entity. Since it is not obviously clear what a release group is, nor the kinds of releases that can be "grouped", this page explains and gives some guidelines on how to handle them.

Both release groups and releases are "albums" in colloquial sense, but with a slight difference: a release is something you can buy as media, e.g. a CD, a vinyl record etc. on its own, while a release group embraces the concept of an album -- it doesn't matter how many CDs or editions/versions it had. When an artist tells you "We've released our new album", he's talking about a release group. When his publisher says "This new album gets released next week in Japan and next month in Europe", he's talking about the different releases that belong in the release group that the artist told you about.

Therefore a release group could contain:

• A "regular" release consisting of one or multiple discs, e.g. Transplant's single "Diamonds and Guns", or a 3 disc self titled compilation by "Nirvana".
• Multi volume boxsets and various artist compilations, like Mozart's 9 volume, 170 disc "Wolfgang Amadeus Mozart: Complete Works" boxset, or the compilation "Bravo Hits 64".
• Different editions (special, limited, bonus etc.) with additional or alternative tracks and/or discs, e.g. There are 10 editions of Weezer's "Weezer (Red Album)" in the database, and Franz Ferdinand's "Tonight: Franz Ferdinand" was issued: on it's own, with a bonus disc, and on two vinyl records.
• Reissues (remasters, 10th year anniversary editions, etc.) e.g. Blind Guardian's "Nightfall in Middle-Earth" was first released in 1998 and then reissued in 2007, the musical "My Fair Lady" (Original London Cast) was originally released on vinyl in 1959 and then reissued on CD in 1998.

A release group should not consist of:

• Complete compilation series' that have different volumes that were released over time. Typical examples are "Café del Mar", "Hitzone", "Ministry of Sound" and "Now That's What I Call Music!". Each volume's discs belong in a release group though, e.g. "Volume 1" and "Volume 2" of the Trance Voices series.
• Different bootleg recordings of a live show, e.g. bootleg 1 and bootleg 2 of a 1970 Pink Floyd concert in San Francisco.

MusicBrainz automatically considers every release in the database to be part of a release group, even if this group only contains the one release. As an editor you don't have to worry about creating release groups, you will only need to merge existing ones.