ISWC · Musical Work

T-309137306-3

OPTIMIST (UNDERSCORE)

Last verified: October 18, 2026

The ISWC for “OPTIMIST (UNDERSCORE)” is T-309137306-3. ISWCs are ISO 15707 identifiers managed by CISAC; they identify the underlying song — its melody, lyrics, and arrangement — rather than any single recording. One composition can have many recordings (ISRCs).

Format

TPrefix

309137306Work number

3Check digit

Prefix:: "T" = musical work; "W" = work in progress.
Work number:: 9-digit unique work number assigned by CISAC.
Check digit:: ISO 7064 Mod 11-2 check digit that validates the rest of the code.

SourcesCISACMLCMusicBrainz3 sources

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What is ISWC T-309137306-3?

T-309137306-3 is an International Standard Musical Work Code (ISWC) that uniquely identifies the musical composition “OPTIMIST (UNDERSCORE)”. ISWCs are defined by ISO 15707 and managed by CISAC. Unlike ISRCs which identify recordings, an ISWC identifies the underlying song — the melody, lyrics, and arrangement.

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T-309137306-3

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What is ISWC T-309137306-3?

T-309137306-3

Format

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What is ISWC T-309137306-3?