Documentation and publication: crosswalk to external standards
The external standards in the crosswalk domains of documentation and publication, from the register, with the relation of each to the Nexus Standards. Each row links to the issuing body, and each relation is evidenced by attestations identified by UNIs (Unique Nexus Identifier).
- Nexus Standards: NS-2, NS-4, NS-7, NS-8.
- Open standards: DataCite Metadata Schema 4.5; Citation File Format (CITATION.cff); CodeMeta; Schema.org CreativeWork; FAIR Signposting profile.
- Data and feeds: Zenodo REST API; Crossref REST API (works); DataCite REST API (DOIs).
- Couples with: Identification (the UNI); Naming, marks and intellectual property; Indexing and discovery.
The process.
The crosswalk as a table: 25 external standards by domain
| Domain | External standard | Issuing body | Relation |
|---|---|---|---|
| Identifiers and cataloguing | DataCite Metadata Schema 4.5 | DataCite Metadata Working Group | adopt |
| Identifiers and cataloguing | Digital Object Identifier system – ISO 26324 | ISO/TC 46/SC 9; International DOI Foundation | crosswalk |
| Identifiers and cataloguing | International Standard Name Identifier (ISNI) – ISO 27729 | ISO/TC 46/SC 9; ISNI International Agency | cite |
| Identifiers and cataloguing | ISO 3166-1 Codes for the representation of names of… | ISO/TC 46; ISO 3166 Maintenance Agency | adopt |
| Identifiers and cataloguing | Open Badges 3.0 | 1EdTech Consortium | adopt |
| Identifiers and cataloguing | ORCID iD (subset of ISNI, ISO 27729) | ORCID Inc. | adopt |
| Identifiers and cataloguing | Research Organization Registry (ROR) | ROR (California Digital Library, Crossref, DataCite) | adopt |
| Identifiers and cataloguing | SoftWare Hash IDentifier (SWHID) Specification V1.2… | Software Heritage; ISO/IEC JTC 1 | adopt |
| Identifiers and cataloguing | UN M49 Standard country or area codes for statistical use | United Nations Statistics Division | adopt |
| Identifiers and cataloguing | W3C Decentralized Identifiers (DIDs) v1.0 | W3C DID Working Group | profile |
| Licensing and intellectual property | Creative Commons Attribution 4.0 International (CC BY 4.0)… | Creative Commons | adopt |
| Licensing and intellectual property | ODRL Information Model 2.2 | W3C | adopt |
| Licensing and intellectual property | Open Definition 2.1 | Open Knowledge Foundation | adopt |
| Licensing and intellectual property | REUSE Specification | Free Software Foundation Europe | adopt |
| Licensing and intellectual property | RFC 5378 Rights Contributors Provide to the IETF Trust… | IETF Trust | cite |
| Licensing and intellectual property | SPDX License List | SPDX Legal Team (Linux Foundation) | adopt |
| Licensing and intellectual property | The Open Source AI Definition | Open Source Initiative | cite |
| Licensing and intellectual property | The Open Source Definition | Open Source Initiative | adopt |
| Licensing and intellectual property | W3C Software and Document License (2023 version) | World Wide Web Consortium | adopt |
| Provenance and evidence | C2PA Content Credentials specification | Coalition for Content Provenance and Authenticity (Joint Development Foundation) | adopt |
| Provenance and evidence | IETF SCITT architecture (Supply Chain Integrity… | IETF SCITT working group | profile |
| Provenance and evidence | in-toto Attestation Framework | in-toto project (CNCF) | adopt |
| Provenance and evidence | Sigstore (Cosign, Fulcio, Rekor) | OpenSSF (Linux Foundation); graduated project March 2024 | adopt |
| Provenance and evidence | W3C PROV-O: The PROV Ontology | W3C Provenance Working Group | adopt |
| Provenance and evidence | W3C Verifiable Credentials Data Model v2.0 | W3C Verifiable Credentials Working Group | crosswalk |
Nexus Standards in the graph: NS-2, NS-4, NS-7, NS-8. A relation is a register entry, never a compliance claim.
4 Nexus Standards · 3 domains · 25 external standards · 24 issuing bodies · 0 implementing repositories. Relations (adopt, profile, crosswalk, cite) are as recorded in the register; names and standards remain with their stewards.
Crosswalk graph56 nodes and 62 links from the registry of external standards, programme areas and implementations (the external standards register, the consumers register. Relations (adopt, profile, crosswalk, cite) are shown as recorded in the register.
- Nexus Standards
- 4
- NS-2, NS-4, NS-7
- Open standards
- 5
- named, never copied
- Data and feeds
- 3
- listed for reference
- Couplings
- 3
- with other areas
Identifiers and cataloguing
10 register entries.
| Standard | Body | Version | Relation | Access | Verified |
|---|---|---|---|---|---|
| SoftWare Hash IDentifier (SWHID) Specification V1.2; ISO/IEC 18670:2025 | Software Heritage; ISO/IEC JTC 1 | 1.2 (ISO/IEC 18670:2025, April 2025) | adopt | open | verified |
| W3C Decentralized Identifiers (DIDs) v1.0 | W3C DID Working Group | W3C Recommendation 19 July 2022 | profile | open | verified |
| DataCite Metadata Schema 4.5 | DataCite Metadata Working Group | 4.5 (22 January 2024) | adopt | open | verified |
| Digital Object Identifier system – ISO 26324 | ISO/TC 46/SC 9; International DOI Foundation | ISO 26324:2022 withdrawn March 2025 and replaced by ISO 26324:2025 | compatibility profile (restricted) | paywalled | unverified |
| ORCID iD (subset of ISNI, ISO 27729) | ORCID Inc. | 16-digit identifier with ISO/IEC 7064 MOD 11-2 check digit | adopt | open | verified |
| International Standard Name Identifier (ISNI) – ISO 27729 | ISO/TC 46/SC 9; ISNI International Agency | ISO 27729 | cite | paywalled | unverified |
| Research Organization Registry (ROR) | ROR (California Digital Library, Crossref, DataCite) | schema v2 (v1 retired December 2025 per secondary source); CC0 data | adopt | open | verified |
| ISO 3166-1 Codes for the representation of names of countries and their subdivisions – Part 1: Country codes | ISO/TC 46; ISO 3166 Maintenance Agency | current (alpha-3 used in the UNI REGION segment) | adopt | free-to-read | unverified |
| UN M49 Standard country or area codes for statistical use | United Nations Statistics Division | online edition of Series M, No. 49 | adopt | open | verified |
| Open Badges 3.0 | 1EdTech Consortium | 3.0 | adopt | open | unverified |
Unverified entries rest on a secondary source for at least one field, as indicated in the register.
Provenance and evidence
6 register entries.
| Standard | Body | Version | Relation | Access | Verified |
|---|---|---|---|---|---|
| Sigstore (Cosign, Fulcio, Rekor) | OpenSSF (Linux Foundation); graduated project March 2024 | project; Rekor v2 general availability reported October 2025 | adopt | open | verified |
| in-toto Attestation Framework | in-toto project (CNCF) | 1.0 (stable per in-toto.io) | adopt | open | verified |
| W3C PROV-O: The PROV Ontology | W3C Provenance Working Group | W3C Recommendation 30 April 2013 | adopt | open | verified |
| W3C Verifiable Credentials Data Model v2.0 | W3C Verifiable Credentials Working Group | W3C Recommendation 15 May 2025 | crosswalk | open | verified |
| C2PA Content Credentials specification | Coalition for Content Provenance and Authenticity (Joint Development Foundation) | 2.1 | adopt | open | unverified |
| IETF SCITT architecture (Supply Chain Integrity, Transparency and Trust) | IETF SCITT working group | draft | profile | open | unverified |
Unverified entries rest on a secondary source for at least one field, as indicated in the register.
Licensing and intellectual property
9 register entries.
| Standard | Body | Version | Relation | Access | Verified |
|---|---|---|---|---|---|
| SPDX License List | SPDX Legal Team (Linux Foundation) | 3.27.0 (1 July 2025) per packaging metadata | adopt | open | unverified |
| RFC 5378 Rights Contributors Provide to the IETF Trust (BCP 78) and IETF Trust Legal Provisions | IETF Trust | BCP 78; Revised BSD License for code components | cite | open | unverified |
| W3C Software and Document License (2023 version) | World Wide Web Consortium | in effect since 1 January 2023 | adopt | open | verified |
| The Open Source Definition | Open Source Initiative | 1.9 (last modified 22 March 2007); ten criteria | adopt | open | verified |
| The Open Source AI Definition | Open Source Initiative | 1.0 (October 2024) | cite | open | verified |
| Open Definition 2.1 | Open Knowledge Foundation | 2.1 | adopt | open | verified |
| Creative Commons Attribution 4.0 International (CC BY 4.0) as used for specification text | Creative Commons | 4.0 | adopt | open | verified |
| ODRL Information Model 2.2 | W3C | 2.2 | adopt | open | unverified |
| REUSE Specification | Free Software Foundation Europe | 3.3 | adopt | open | unverified |
Unverified entries rest on a secondary source for at least one field, as indicated in the register.
Relation types and their evidence
| Relation | Meaning | Evidence |
|---|---|---|
cite | The Nexus Standard refers to the external standard as context. | Identifier, version and URL in the register. |
profile | The Nexus Standard constrains or specialises an open external standard (for example STAC, DCAT, PROV-O, DataCite, CAP). | Conformance tests against the external standard’s own validator where one exists. |
crosswalk | Elements of the external standard map to Nexus elements (clauses, record fields). | A crosswalk table in the register entry; each row cites the external clause by number, never by text. |
adopt | The Nexus Standards use the external standard as it is for a function (for example ISO 3166-1, SPDX, ORCID, ROR). | Validation of values against the external scheme. |
extend | A Nexus Standard adds machine-readable, real-time or provenance elements that the external standard lacks. | The extension is a Nexus clause or field; the external standard is cited as the baseline. |
gap | No external standard covers the concern; a Nexus Standard specifies it. | The gap statement in the landscape study. |
Questions and answers.
Does a crosswalk establish that a documentation and publication artefact conforms to these standards?
Why are some relations shown as compatibility profile (restricted)?
Why are some entries marked unverified?
Around documentation and publication.
Shape the standards for documentation and publication.
Governments, regulators, standards bodies, industry, academia and communities are invited to shape the catalogue ahead of its first official release, targeted for 2030: comment on a draft, propose a change, join a working group or host a field exercise.
Status and use. The Nexus Standards are proposed standards developed through an open process under NS-13 and published for voluntary use; they do not constitute certification, accreditation or regulatory approval, and adoption remains a decision of the Global Standards Council and, in each country, of its National Standards Council. A UNI (Unique Nexus Identifier) identifies an artefact; it does not certify it. Names of standards bodies and their standards belong to their stewards and are used only to identify the documents; no text of an external standard is reproduced here. Nexus Standards is not affiliated with, endorsed by or certified by any standards body named here.
Licences: CC BY 4.0 for standards text, registries, schemas and data; Apache-2.0 for reference code. External standards are cited by name, number and link under their own licences. Third-party data, libraries and fonts keep their own licences: see Third-party notices.