A named, formally-defined system for constructing, issuing, and resolving identifiers, typically defined by a syntax, an authority structure (who can mint), a metadata schema, and a resolution policy.

ByCASRAI Editorial Board

· Last updated 10 Jul 2026

Examples

Worked examples

Is an instance
'doi' as a scheme value alongside the identifier '10.1038/nature14539' in a metadata record.
Is an instance
'orcid' as a scheme indicating that the accompanying identifier is an ORCID iD.

Counter-examples

Looks similar, but isn't

Not an instance
'paper' is not an identifier scheme — it describes the entity type, not the naming system.
Not an instance
'unique' is not an identifier scheme.

Editorial commentary

Examples of identifier schemes include DOI, Handle, ARK, ORCID, ROR, ISNI, URN, UUID. Each scheme is defined by some combination of standards documents (ISO standards, IETF RFCs, community specifications), governing bodies (DataCite, Crossref, CNRI, ORCID Inc., etc.), and operational infrastructure (registries, resolvers). When a CRIS or repository must record an identifier, declaring ‘which scheme this is’ is essential to interpretation — ‘12345’ alone is meaningless without the scheme.

References

Klump J., Wyborn L., 'Identifiers for the 21st Century', Data Science Journal 16(28), 2017.

Also known as

PID scheme

Machine-readable encodings

Use in your systems

JATS XML <role> element

xml

<role vocab="credit"
      vocab-identifier="https://casrai.org/dictionary/"
      vocab-term="Identifier scheme"
      vocab-term-identifier="https://casrai.org/dictionary/term/identifier-scheme" />

Schema.org DefinedTerm (JSON-LD)

json

{
  "@context": "https://schema.org",
  "@type": "DefinedTerm",
  "@id": "https://casrai.org/dictionary/term/identifier-scheme",
  "name": "Identifier scheme",
  "identifier": "https://casrai.org/dictionary/term/identifier-scheme",
  "description": "A named, formally-defined system for constructing, issuing, and resolving identifiers, typically defined by a syntax, an authority structure (who can mint), a metadata schema, and a resolution policy.",
  "inDefinedTermSet": "https://casrai.org/dictionary/domain/persistent-identifiers#set",
  "url": "https://casrai.org/dictionary/term/identifier-scheme",
  "sameAs": [
    "PID scheme"
  ],
  "license": "https://creativecommons.org/licenses/by/4.0/",
  "publisher": {
    "@id": "https://casrai.org/#organization"
  },
  "dateModified": "2026-07-10T02:06:20",
  "inLanguage": "en"
}

Referenced across the research world

View CASRAI adoption →