By Nick Landis on Tuesday Aug, 14th 2018

The International Standard Musical Work Code, or ISWC, is a unique identifier for musical works. Like the ISRC is for recordings and the ISNI is for people, the ISWC helps identify and disambiguate musical works. Along with being a unique identifier, the ISWC is also permanent and an internationally recognized ISO reference number for the identification of musical works. This code is part of the Common Information System (CIS) developed by the Confederation of Societies of Authors (CISAC) to help meet the needs and challenges of the digital information age.

In the United States, ASCAP is the official issuing entity. Even if you aren't a member of ASCAP, you can have a number issued so you can use it in your metadata. For each work, you would go to ASCAP and get them to assign a code to your piece if you have all the required information to allocate a code. ISWC must be allocated by an authorized national or regional ISWC agency. (At the time of writing this article, I did not find a place to do this on the ASCAP website)

How To Allocate an ISWC

When registering a composition, you will typically need everything you would need to submit it for publishing to your PRO (ASCAP, BMI, etc...) like the title of the work, all the composers that helped to write the song, and what kind of work the piece is. Additionally, an ISWC is only allocated by a qualified numbering agency when all the creators have been uniquely identified. This is directly from the ISWC site:

The descriptive metadata for an ISWC includes:

  • the title of the work
  • all composers, authors and arrangers of the work identified by their IPI numbers and role codes
  • the work classification code (from the CIS standards list)
  • in the case of 'versions', for example arrangements, identification of the work from which the version was made.

Without this minimum information, an ISWC cannot be allocated.

So, there are three new things for me. The CIS standard classification code, IPI numbers for authors and arrangers, and role codes. I guess that's an article for another time. Anyways, back to the ISWC.

The ISWC codes all start with the letter T, then followed by a 9-digit catalog number, and a final check digit. For example, T-345246800-1.