Short for International Standard Works Code, an internationally recognized reference number for the identification of musical works. The code that is applied to a musical work is permanent and stays with the work even when it is transferred across national borders. An ISWC begins with the letter "T", followed by a nine-digit unique number (from 00000001 to 999999999), and an additional check digit at the end.
The ISWC is an ISO-approved standard. The International ISWC Agency, which is appointed by ISO, is responsible for the overall ISWC system maintenance and administration.