Credential Transparency Description Language (CTDL)
- Stuart Sutton
- Jeanne Kitchens
All terms (properties & classes) used in metadata descriptions that conform to the Credential Transparency Description Language (CTDL) must be assigned a unique URI. The term URIs that are assigned and managed by Credential Engine (CE) are grouped into collections known as CTDL namespaces. This document describes how term URIs are allocated by CE and the policies associated with CTDL namespaces.
This document uses of the following terminology:
Term URIs are grouped into CTDL namespaces in order to ease the assignment of URIs to terms and to streamline their use in particular serializations. Note that the grouping of term URIs into CTDL namespaces is orthogonal to the grouping of terms into sets designed to meet other functional needs, e.g., as various types of vocabularies, particular profiles, or as specific graph shapes or record structures.
The CTDL namespace URI (base URI) for the collection of all CTDL properties, classes and concept schemes is:
The CTDL namespace URI (base URI) for the concept classes in the CTDL concept schemes (controlled vocabularies) are:
https://purl.org/ctdl/vocabs/actionStat/ https://purl.org/ctdl/vocabs/agentSector/ https://purl.org/ctdl/vocabs/assessMethod/ https://purl.org/ctdl/vocabs/assessUse/ https://purl.org/ctdl/vocabs/audience/ https://purl.org/ctdl/vocabs/audLevel/ https://purl.org/ctdl/vocabs/claimType/ https://purl.org/ctdl/vocabs/costType/ https://purl.org/ctdl/vocabs/credentialStat/ https://purl.org/ctdl/vocabs/creditUnit/ https://purl.org/ctdl/vocabs/deliveryType/ https://purl.org/ctdl/vocabs/inputType/ https://purl.org/ctdl/vocabs/learnMethod/ https://purl.org/ctdl/vocabs/orgType/ https://purl.org/ctld/vocabs/purpose/ https://purl.org/ctdl/vocabs/residency/ https://purl.org/ctdl/vocabs/score/ https://purl.org/ctdl/vocabs/serviceType/
Some example CTDL term URIs
...is the CTDL term URI for the Industry Type property.
...is the CTDL term URI for the Digital Badge class.
...is the CTDL term URI for the Claim Type concept scheme (vocabulary) class.
...is the CTDL term URI for the Badge Claim concept (vocabulary term) class.
CTDL terms Change Policy
Changes to CTDL terms or term declarations will occur from time to time for a variety of reasons. Such changes have varying implications for CTDL term URIs and CTDL namespaces. The following kinds of changes are identified along with examples and associated implications.
In all cases, any changes to CTDL terms or term declarations will result in an update to the versioning information carried in the CTDL term declaration associated with that term.
Minor Editorial Errata
Errors of spelling, punctuation, or other clerical mistakes discovered in CTDL term declarations will be corrected without a comment period, following notification to the CTDL Technical Advisory Committee (TAC), as long as, in the judgment of the CE Technical Team, there are no implications for negative impact on users or applications that rely on those CTDL term declarations. If the CE Technical Team is uncertain as to potential negative impact of such a change, a comment period will be declared on notification of the TAC.
Correction of minor editorial errata will result in no changes to CTDL term URIs.
Semantic changes in CTDL terms
Changes of definitions within a CTDL term declaration will be reflected in the affected CTDL term declaration. If, in the judgment of the CE Technical Team, such changes of meaning are likely to have substantial impact on either machine processing of CTDL terms or the functional semantics of the terms, then these changes will be reflected in a change of URI for the CTDL term or terms in question. The URIs for any new CTDL namespaces resulting from such changes will conform to the CTDL namespace URI patterns defined above.
Addition of CTDL term declarations to existing CTDL namespaces
New CTDL term URIs will occasionally be added to existing CTDL namespaces. Addition of CTDL term URIs to existing CTDL namespaces will not trigger changes in CTDL namespace URIs.
Credential Engine (CE) recognizes that people and applications depend on the persistence of formal documents and machine processable schemas that have been made publicly available. In particular, the stability of CTDL term URIs and CTDL namespace URIs is critical to interoperability over time. Thus, the wide promulgation of this set of URIs dictates that they be maintained to support legacy applications that have adopted them.
The Credential Transparency Description Language (CTDL) Namespace Policy is adapted from the Namespace Policy for the Dublin Core Metadata Initiative (DCMI).