Examples
Worked examples
- Is an instance
urn:isbn:0-486-27557-4 (a book).
- Is an instance
urn:nbn:de:bsz:14-qucosa-123456 (a German national bibliography number).
Counter-examples
Looks similar, but isn't
- Not an instance
https://example.org/paper.pdf is a URL, not a URN.
- Not an instance
A DOI in its HTTPS form (https://doi.org/...) is a URL even though it names persistently.
Editorial commentary
A URN (Uniform Resource Name) is a persistent, location-independent identifier defined by IETF RFC 8141, taking the form urn:NID:NSS, where NID is a registered Namespace Identifier (registered with IANA) and NSS is a namespace-specific string whose own internal format is defined by that namespace. URNs were one of the three originally-proposed families of URI alongside URLs and URCs in early web-architecture terminology; unlike a URL, a URN by itself does not imply any particular resolution mechanism — it names a resource persistently without necessarily telling a client where or how to retrieve it.
Scope note
URN is fundamentally an IETF/web-architecture naming specification, and most of the public discussion of URNs (syntax edge cases, resolver implementations, namespace-registration procedure) is squarely a developer/library-systems topic rather than a research-administration one. The RDM-relevant angle, kept deliberately narrow here, is where a research-administration or repository professional actually encounters a URN in practice.
Where a repository or CRIS manager meets a URN
The urn:nbn: namespace (National Bibliography Number) is the practically important case: national libraries in Germany, Finland, the Netherlands and several other European countries assign urn:nbn: identifiers at scale to items in their national bibliography, including university theses and dissertations submitted through institutional repositories. A repository manager depositing a thesis with one of these national systems will typically receive back a urn:nbn: string as the work’s persistent citation identifier — distinct from, and often used alongside, a DOI if the institution also mints one. Other common namespaces a metadata professional may encounter include urn:isbn: (wrapping an ISBN as a URN) and urn:issn:; urn:doi: existed historically as a way to express a DOI as a URN but is now deprecated in favour of DOIs’ own native https://doi.org/ resolution.
Worked example / counter-example
urn:nbn:de:bsz:14-qucosa-123456 names a specific item in the German national bibliography persistently, independent of which server currently hosts it — resolving it requires a separate NBN resolver service, since the URN itself carries no location. By contrast, https://example.org/paper.pdf is a URL, not a URN — it names a location, and if that server or path changes, the identifier breaks; a DOI expressed in its resolvable https://doi.org/ form is likewise a URL in form even though the underlying DOI system is designed for persistence.
References
- Saint-Andre, P., Klensin, J., RFC 8141, “Uniform Resource Names (URNs),” IETF, 2017.
Also known as
Uniform Resource Name
Machine-readable encodings
Use in your systems
<role vocab="credit"
vocab-identifier="https://casrai.org/dictionary/"
vocab-term="URN"
vocab-term-identifier="https://casrai.org/dictionary/term/urn" />{
"@context": "https://schema.org",
"@type": "DefinedTerm",
"@id": "https://casrai.org/dictionary/term/urn",
"name": "URN",
"identifier": "https://casrai.org/dictionary/term/urn",
"description": "Uniform Resource Name (RFC 8141), a URI of the form urn:NID:NSS where NID is a registered Namespace Identifier and NSS is the namespace-specific string, intended to denote a resource persistently and independently of any particular resolution mechanism.",
"inDefinedTermSet": "https://casrai.org/dictionary/domain/persistent-identifiers#set",
"url": "https://casrai.org/dictionary/term/urn",
"sameAs": [
"Uniform Resource Name"
],
"license": "https://creativecommons.org/licenses/by/4.0/",
"publisher": {
"@id": "https://casrai.org/#organization"
},
"author": {
"@id": "https://casrai.org/#editorial-team"
},
"datePublished": "2026-05-21T02:10:43",
"dateModified": "2026-08-22T16:26:48",
"inLanguage": "en-GB",
"isAccessibleForFree": true
}
