Why many registered works have no ISWC
The ISWC is the standard identifier for a musical work. It is also missing from a large share of registered works, and a songwriter’s catalogue built from ISWCs alone leaves those works out.
Figures measured 2026-09-15 on the registration data Songlinks reads.
What an ISWC is, and when a work gets one
An International Standard Musical Work Code identifies a composition, as distinct from any recording
of it. In the data it looks like T0702425135. ISWCs are allocated by registration
agencies, usually the collecting societies, once a work’s complete metadata is known. That
includes the original title and the IPI name number and role of every creator
(ISWC International Agency).
How many works have none
We took a random sample of songwriter records that carry an IPI name number, 1,018 of them, and looked at every work registered to each:
- 66% of those works carried an ISWC, so about a third did not.
- For 15% of the writers (155 of 1,018), none of their registered works had an ISWC.
- For about half (518 of 1,018), every work did.
That sample is the favourable case: records with an IPI name number. About six in ten songwriter records have none (why that matters).
Why a work can lack one
The allocation rule explains a good part of it. An ISWC needs the complete metadata, including an IPI name number for every creator, and registration data is often incomplete: a co-writer with no number, a creator registered only by name, a work registered before its details were settled. Registration data records the work either way. The code may simply never have been assigned, or never have reached the registration you are looking at.
What a list built from ISWCs misses
- Whole catalogues. A writer whose 13 registered works carry no ISWC looks, to any list keyed on ISWCs, as though they have registered nothing.
- Part of every catalogue. With a third of works uncoded, a count of ISWCs understates what most writers have registered.
- Duplicates that look like separate works. The same title is often registered as two works, one with an ISWC and one without. In the first 100 titles of Mick Jagger’s list, 10 appear twice.
Finding a writer’s uncoded works
- Start from the writer’s registrations, every spelling and number, not from ISWCs.
- Keep works with no ISWC in the count, and match them on title and co-writers.
- Expect the same title twice, and check before counting it as two songs.
Songlinks lists every work registered under the records it groups into one writer, with or without an ISWC. It is in beta, and no person has checked its answers: try a lookup.