What is an ISWC code?

International Standard Musical Work Code (ISWC) is a unique identifier for musical works, similar to ISBN for books. It is adopted as international standard ISO 15707. The ISO subcommittee with responsibility for the standard is TC 46/SC 9.
To register an ISWC, the following minimal information must be supplied:
-       Title
-       Names of all composers, arrangers and authors, with their role in the piece (identified by role code) and their CAE/IPI number
-       Work classification code (CIS)
-       Identification of other works it is a derivative of 

An ISWC identifies works, not recordings. ISRC can be used to identify recordings. Nor does it identify individual publications (e.g. issues of a recording on physical media, sheet music, broadcast at a particular frequency/modulation/time/location...)
Its primary purpose is in collecting society administration, and to clearly identify works in legal contracts. It would also be useful in library cataloguing.
Releese can provide you with an ISWC code when publishing your content on Rights Cloud for free.