ISWC stands for “International Standard Musical Work Code.” It is a unique, internationally recognized 11-character identifier for individual musical works. ISWC numbers identify works/songs, not recordings. The same ISWC may be applied to multiple recordings – for example, a cover and a remix of a song will all have the same ISWC as each recording is using the same work.
It is divided into three elements, consisting of the letter T (the “prefix element”), followed by nine digits (the “work identifier”) and a numeric check digit.
Example ISWC: T-000.000.001-0