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: Alternate Canonical

Official URL: http://hl7.org/fhir/StructureDefinition/alternate-canonical Version: 5.3.0-ballot-tc1
Standards status: Trial-use Maturity Level: 2 Computable Name: AlternateCanonical
Other Identifiers: OID:2.16.840.1.113883.4.642.5.1674

Used with inter-version extensions where the element being referenced by inter-version extension is of type 'canonical' and includes a reference to a resource whose canonical URL is different in the referencing version than it is in the FHIR version where the element was defined. E.g. if an R5 implementation were using inter-version extensions to support an element that referenced Bar, when in R7, the url would have been …/Foo. In this situation, the canonical element would have no value and would instead have an extension that referred to the canonical URL of the '../Bar' resource (which would technically not be supported in R7, but is appropriate in R5).

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 url: Used with inter-version extensions where the element being referenced by inter-version extension is of type 'canonical' and includes a reference to a resource whose canonical URL is different in the referencing version than it is in the FHIR version where the element was defined. E.g. if an R5 implementation were using inter-version extensions to support an element that referenced Bar, when in R7, the url would have been .../Foo. In this situation, the canonical element would have no value and would instead have an extension that referred to the canonical URL of the '../Bar' resource (which would technically not be supported in R7, but is appropriate in R5).

    Maturity: 2

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..1 Extension Alternative reference (target type is wrong)
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/alternate-canonical"
    ... value[x] 1..1 url Value of extension

    doco Documentation for this format
    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..1 Extension Alternative reference (target type is wrong)
    ... id 0..1 id Unique id for inter-element referencing
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/alternate-canonical"

    doco Documentation for this format

    This structure is derived from Extension

    Summary

    Simple Extension with the type url: Used with inter-version extensions where the element being referenced by inter-version extension is of type 'canonical' and includes a reference to a resource whose canonical URL is different in the referencing version than it is in the FHIR version where the element was defined. E.g. if an R5 implementation were using inter-version extensions to support an element that referenced Bar, when in R7, the url would have been .../Foo. In this situation, the canonical element would have no value and would instead have an extension that referred to the canonical URL of the '../Bar' resource (which would technically not be supported in R7, but is appropriate in R5).

    Maturity: 2

    Differential View

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..1 Extension Alternative reference (target type is wrong)
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/alternate-canonical"
    ... value[x] 1..1 url Value of extension

    doco Documentation for this format

    Snapshot View

    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..1 Extension Alternative reference (target type is wrong)
    ... id 0..1 id Unique id for inter-element referencing
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/alternate-canonical"

    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 not used in R3

    • There are no valid contexts for this extension

    Search Parameters for this Extension

    (none found)