The list of Known Identifier Systems in FHIR (https://build.fhir.org/identifier-registry.html) includes Uniform Resource Identifiers (URIs), but not Internationalized Resource Identifiers (IRIs, as defined by RFC 3987 at https://datatracker.ietf.org/doc/html/rfc3987). IRIs are the "internationalized" version of URIs that allow Unicode characters to be used in the identifier with some restrictions, which was defined by the Internet Engineering Task Force (IETF) in 2005. An IRI such as "https://hi.wikipedia.org/wiki/हृदय" can be percent-encoded into the URI "https://hi.wikipedia.org/wiki/%E0%A4%B9%E0%A5%83%E0%A4%A6%E0%A4%AF" to be used as a URL, but the IRI is easier to read, particularly for readers of non-Latin languages, and is natively supported by many tools, including many browsers, HTTP libraries, and in the Resource Description Framework (RDF).

Currently, users cannot use an IRI in a FHIR Coding.code without either making up a Coding.system value for their own use or transforming the IRI into a URI so they can use "urn:ietf:rfc:3986" as the Coding.system value. This change would provide a Coding.system value for IRIs, allowing these widely used Unicode-based identifiers to be used to identify entities in FHIR.

Proposed additional identifier:

• identifier: Internationalized Resource Identifiers (IRIs) as defined by RFC 3987
• URI: urn:ietf:rfc:3987
• OID: [to be registered if necessary]
• Type: [none]
• Comment: As defined by RFC 3987, which also provides an algorithm for converting IRIs to URIs. Example: https://hi.wikipedia.org/wiki/हृदय