CA-004The catalogs
What ISRC and ISWC Codes Actually Identify
An ISRC identifies one recorded version of a track. An ISWC identifies the composition behind every version of it. What each code tracks, and why a cue sheet needs both.
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An ISRC identifies one specific recording: a particular mix, edit or version of a track. An ISWC identifies the musical composition underneath it, the song as written, independent of how many times it has been recorded. A single composition can carry one ISWC and dozens of ISRCs, one for every mix, alt version or re-recording a library issues under that title.
What does an ISRC actually identify?
The International Standard Recording Code is a twelve-character code assigned to one sound recording. It is built from three elements: a five-character prefix allocated by an ISRC agency, a two-digit year of reference and a five-digit designation code, and it stays with that exact recording for its whole lifespan, even when ownership of the track changes. A full mix, an alt mix with the lead pulled out, and a thirty-second cut of the same cue are three different recordings, and each one gets its own ISRC, because the ISRC rules treat a remix or an edit as a new version of the recording even when the underlying song is identical. The International Federation of the Phonographic Industry acts as the International ISRC Registration Authority; national ISRC agencies allocate prefixes to labels, libraries and self-releasing artists in their territory, and the Registration Authority does so directly where no national agency exists.
What does an ISWC actually identify?
The International Standard Musical Work Code identifies the composition itself: the notes, the lyric, the structure a songwriter put on paper, independent of any specific recording. The standard is ISO 15707, its registration authority is the International Confederation of Societies of Authors and Composers, and the codes themselves are allocated by local agencies, usually collecting societies, once a work is registered. The work keeps a single code however many times it is recorded or rerecorded. Two labels that record the same standard in two different studios, with two different singers, are making two recordings with two ISRCs of one composition with one ISWC.
Why does one composition carry several ISRCs?
A library issues a cue as a full mix, then as a set of stems, then as two or three alt mixes built for picture. Each of those deliverables is a distinct recording: a different balance, a different edit, sometimes a different take entirely. None of that changes the composition, so the ISWC on the cue sheet stays the same line after line. What changes is the ISRC on each delivered file, because the system tracks the recording, not the song. A catalog that reissues an older cue with a plain remaster, by contrast, normally keeps the original ISRC: the ISRC guidance asks for a new code only when the remaster brings significant new creative input, or when an edit changes the playing time by more than ten seconds.
Who assigns each code, and how?
A registrant, usually the label or the library itself, applies for an ISRC prefix through its national ISRC agency and then assigns individual recording codes from that prefix as new masters are finished. The ISWC works the other way: a publisher, a composer or a collecting society registers the work once with a member society, which issues the code and shares it across the international ISWC database so that every society recognises the same work under the same number, no matter which territory first filed it.
Why does a cue sheet or a licence need both?
A cue sheet reports a usage back to a performing rights organisation so the composition side can be paid, and that report is matched against the work registration the ISWC identifies. A master licence, separately, clears the specific recording a production actually used, and that clearance is matched against the ISRC. A broadcaster who licenses a cue by ISRC alone has cleared the recording but has not, by itself, triggered the composition's performance royalty; the cue sheet and its ISWC do that part. The two codes travel together on a well-built delivery, because they answer two different questions: who wrote this, and which take is this.
What happens when a code is missing or wrong?
A recording without an ISRC can still be licensed, but a label or a library then has no stable way to tell two mixes apart once a title is reused across volumes, and a royalty statement has to be reconciled by ear instead of by number. A work without a registered ISWC, or one registered twice under two slightly different titles, splits its own royalty history: a PRO sees two works where there is one, and the writer's share is divided against itself rather than paid in full. Neither error is usually caught at the point of recording. It surfaces months later, in a statement that does not add up, when someone has to trace a title back through a catalog that never carried the code it needed.
The two systems exist for the same reason a catalog number exists on a printed octavo: so that a specific object, not just a title, can be found again by someone who was not in the room when it was made.
