CTID
Globally unique Credential Transparency Identifier (CTID) by which the creator, owner or provider of a resource recognizes it in transactions with the external environment (e.g., in verifiable claims involving the resource).
The CTID is the equivalent of a version identifier for the resource. Different versions of a resource are considered distinct expressions and each must be assigned its own CTID. Each version of a resource can have only one CTID assigned. However, a single version of a resource may have distinct identifier values for both the ctid property and the credentialId property. In such a case both identifiers will be recognized by the resource creator/owner/provider in transactions with the external environment.