The Verifiable Credentials Working Group invites implementations of the following Candidate Recommendation Snapshot: Controlled Identifiers (CIDs) v1.0.
A controlled identifier document contains cryptographic material and lists service endpoints for the purposes of verifying cryptographic proofs from, and interacting with, the controller of an identifier.
https://www.w3.org/news/2025/w3c-invites-implementations-of-controlled-identifiers-cids-v1-0/