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4.6 Known Identifier Systems

FHIR Infrastructure icon Work GroupMaturity Level: 3Standards Status: Trial Use

Identifier systems are URIs that may be used in the system element of the Identifier datatype. In the past, this page included a list of registered URIs approved for use. However, this content has been migrated to a location that can be maintained more actively.

HL7 Terminology (http://terminology.hl7.org icon) provides a registry of Identifier systems which are actively curated by HL7 International. If a URI is defined in HL7 Terminology, it SHOULD be used in preference to any other Identifier.system. If the URI was defined in HL7 Terminology prior to an official release of the FHIR core specification, those URIs SHALL be used in preference to any other Identifier.system. I.e. all system URIs defined on terminology.hl7.org prior to the release of FHIR R5 SHALL be used in systems claiming conformance to FHIR R5.

Many identifier systems are 'local', for example the identifiers used for employee numbers, local medical record numbers, local order and encounter numbers, etc. The system URIs for such identifiers are generally determined and managed by the issuing system. However, 'shared' identifiers that are used across a wide variety of systems, such as license numbers, government-assigned identifiers, etc. need to have consistent URIs. In most cases, the assigners of these identifiers will not have published an official URI.

If an identifier system for a 'shared' identifier is not listed in HL7 Terminology, implementers SHOULD (and HL7 international published specifications SHALL) follow the process for determining Identifier.system URIs defined by the HL7 Terminology Authority, as documented here icon.

See also the list of known coding systems that can be used in the system element of the Coding datatype.