Nearly all tangible releases (as opposed to digital media files) have a quasi-unique catalog number, assigned to them by the record label releasing them. Generally, this number will include alphanumeric characters, often letters followed by numbers, perhaps separated by a dash, space or other punctuation. The catalog number is most often printed on the spine of CDs and on the back of sleeves, often near the barcode if one exists, and can indicate both the format of a release (CD, LP etc) and often the label. The catalog number to be entered on Musicbrainz should match the one printed on the sleeve as closely as possible.
1. Catalog numbers supplied by Discogs should be treated with care, as Discogs advises its editors to alter catalog numbers to fit an arbitrary style for some labels. If an image of the sleeve is available, use the catalog number shown on that, rather than the text version listed by Discogs.
2. Many major label imprints use numbers that are similar or exactly the same as the BarCode. Often the only apparent difference is the lack of a check digit, but note that punctuation can be included in the catalog number field on MBz, whereas the BarCode must be made of numbers only.
3. Many releases feature two or more catalog numbers. This is especially true for international releases on imprints controlled by major companies. In cases like this, there are several options.
- a) Create two release events (same date, country, label and barcode) and provide the two cat #s separately. b) Choose the "friendly" cat # for a single release event and list the supplemental cat # in the annotation. c) Recognise that the different catalog numbers relate to releases in different countries, and submit release events accordingly. For example, a CD-single released by Warner Music might specify "W 999CD" for the UK, "W999-2CD" for Germany, and "999-2 CD" for Australia. EMI commonly uses a "friendly" cat number for UK releases, and an unfriendly number (based on the barcode) for other territories. Use the number that matches the release country.
4. Some box sets will have a separate cat number for each disc, and then an overall number that appears on the outer packaging. It is recommended that the catalog number to be entered on MBz matches each individual disc. The number for the overall package can be noted in the release annotation if desired.
5. Some labels include the name of the imprint (or a shortened version) as part of the catalogue number. In cases like these, the imprint name will be printed in the same typeface as the rest of the catalog number, and it should be included on MBz. (Without the name, a number like 01-01 lacks information that is useful for identifying the imprint.)