FHIR Extensions Pack
5.3.0-ballot-tc1 - (September 2025 Ballot) International flag

This page is part of the FHIR Core Extensions Registry (v5.3.0-ballot-tc1: Release 5.3) based on FHIR (HL7® FHIR® Standard) v5.0.0. This version is a pre-release. The current official version is 5.2.0. For a full list of available versions, see the Directory of published versions

Extension: additional identifier

Official URL: http://hl7.org/fhir/StructureDefinition/additionalIdentifier Version: 5.3.0-ballot-tc1
Standards status: Trial-use Maturity Level: 2 Computable Name: AdditionalIdentifier
Other Identifiers: OID:2.16.840.1.113883.4.642.5.1657

An additional identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.

Context of Use

This extension may be used on the following element(s)

Usage info

Usages:

  • This Extension is not used by any profiles in this Implementation Guide

You can also check for usages in the FHIR IG Statistics

Changes since version 5.2.0:

  • The resource metadata has changed (status)

    • Formal Views of Extension Content

    Description of Profiles, Differentials, Snapshots, and how the XML and JSON presentations work.

    This structure is derived from Extension

    Summary

    Simple Extension with the type Identifier: An additional identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.

    Maturity: 2

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..* Extension Additional Logical reference, when literal reference is not known
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/additionalIdentifier"
    ... value[x] 1..1 Identifier Value of extension

    doco Documentation for this format
    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..* Extension Additional Logical reference, when literal reference is not known
    ... id 0..1 id Unique id for inter-element referencing
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/additionalIdentifier"

    doco Documentation for this format

    This structure is derived from Extension

    Summary

    Simple Extension with the type Identifier: An additional identifier for the target resource. This is used when there is no way to reference the other resource directly, either because the entity it represents is not available through a FHIR server, or because there is no way for the author of the resource to convert a known identifier to an actual location. There is no requirement that a Reference.identifier point to something that is actually exposed as a FHIR instance, but it SHALL point to a business concept that would be expected to be exposed as a FHIR instance, and that instance would need to be of a FHIR resource type allowed by the reference.

    Maturity: 2

    Differential View

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..* Extension Additional Logical reference, when literal reference is not known
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/additionalIdentifier"
    ... value[x] 1..1 Identifier Value of extension

    doco Documentation for this format

    Snapshot View

    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..* Extension Additional Logical reference, when literal reference is not known
    ... id 0..1 id Unique id for inter-element referencing
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/additionalIdentifier"

    doco Documentation for this format

     

    Other representations of profile: CSV, Excel, Schematron

    Constraints

    IdGradePath(s)DetailsRequirements
    ele-1error**ALL** elementsAll FHIR elements must have a @value or children
    : hasValue() or (children().count() > id.count())
    ext-1error**ALL** extensionsMust have either extensions or value[x], not both
    : extension.exists() != value.exists()

    R4B

    The extension is unchanged in R4B

    R4

    The extension is unchanged in R4

    R3

    The extension is unchanged in R3

    Search Parameters for this Extension

    (none found)