The tune data under /session/ contains information from The Session
(https://thesession.org), which is made available here under the Open
Database License (ODbL) — https://opendatacommons.org/licenses/odbl/1.0/.
Tune transcriptions are community contributions to The Session, shared
under the contents license in the source repository:
https://github.com/adactio/TheSession-data (LICENSE.md).

Snapshot: 211271533a254369c3f22510d8121dfee254d9f7
This derived database (index + shards) is itself available under the
ODbL at these public URLs; the transform that produced it is
scripts/build-session-library.mjs in the Windway source tree.