The element IRI contains an International Resource Identifier that serves as a name for the a concept, person, or thing referred to by the parent element. IRIs are explained at the section called “Identifiers and Their Use”.

Any kind of IRIs are allowed: URLs, tag URNs, UUIDs, etc. For names of well-known resources, a URL identifier might be preferred (http://...), to facilitate linked data. If an entity/resource lacks a suitable URL-type name, you may use or coin any other valid IRI, such as a UUID, a tag URN, or an OID. Some concepts may be difficult to find IRIs for.

Sibling <IRI>s are to be treated as names for the same thing, not as names of different things. Nevertheless, they are not synonymous, only poecilonymic. In the terms of Web Ontology Language (http://www.w3.org/TR/owl-ref/), sibling <IRI>s cannot be assumed to share the relationship owl:sameAs, because they will draw from independent vocabularies that may define similar concepts differently.

An element defined with multiple <IRI>s is technically within the intersection, not the union, of those definitions. Nevertheless, most interpretations of TAN files will draw inferences based upon the union. That is, if item A is defined by IRI X, item B by IRIs X and Y, and item C with IRI Y, it is likely that users of the data will infer identity between items A and C. It is advisable to be cautious is assigning multiple IRIs to entities.

The element is named IRI instead of URI to encourage internationalization. Alphabets other than the Latin are welcome.

Formal Definition

~ed-stamp?, anyURI (pattern [a-zA-Z][\-.+a-zA-Z0-9]+:\S+)

Defined at: TAN-core.rng

Used by: ~entity-digital-tan-other-ref, ~entity-digital-generic-ref, ~entity-nondigital-ref


An IRI may appear no more than once in a TAN document.


An IRI that names a TAN file must match that file's @id exactly.


Any IRI beginning urn: must continue with a name that is part of the official IANA Registry of URN Namespaces. See RFC 2414, https://tools.ietf.org/html/rfc8141, and https://www.iana.org/assignments/urn-namespaces/urn-namespaces.xhtml


No file may import keys that have duplicate IRIs.


All text must be normalized (Unicode NFC).


Every item in a reserved TAN-key must have at least one IRI with a tag URN in the TAN namespace

Example 8.135. <IRI>

<TAN-T id="tag:kalvesmaki.com,2014:tan-t:ar.cat.eng.1926.edghill:model-object-refs" TAN-version="2018">
         <name>Creative Commons Attribution 4.0 International License</name>
         <name>Aristotle: Categoriae & De interpretatione by E.M. Edghill. Analytica priora / by
            A.J. Jenkinson. Analytica posteriora / by G.R.G. Mure. Oxford : Clarendon Press, 1926.
      <see-also relationship="ade">
         <name>Categories, Aristotle, English translation by E. M. Edghill</name>
      <see-also relationship="model">
         <name>Categories, Aristotle, Greek text by Minio-Paluello</name>


Taken from ar.cat.eng.1926.edghill.obj