Version 0.5.0 of the open exchange and preservation standard for digital representations of musical instruments and other acoustic objects. This release adds identified cross-carrier distributions, carrier and descriptor fixity, release-inventory validation, and a two-carrier repository profile for bootstrap and preservation delivery. Specification text, schemas, semantic artifacts, fixtures, and knowledge documentation are CC BY 4.0; reference software, tests, and automation are Apache-2.0. The authoritative per-file mapping is in REUSE.toml.