FHIR Extensions Pack
5.4.0 - May 2026 International flag

FHIR Extensions Pack, published by HL7 International / FHIR Infrastructure. This guide is not an authorized publication; it is the continuous build for version 5.4.0 built by the FHIR (HL7® FHIR® Standard) CI Build. This version is based on the current content of https://github.com/HL7/fhir-extensions/ and changes regularly. See the Directory of published versions

Extension: Additional Resource Reference Target

Official URL: http://hl7.org/fhir/StructureDefinition/additional-resource-reference-target Version: 5.4.0
Standards status: Trial-use Maturity Level: 1 Computable Name: AdditionalResourceReferenceTarget
Other Identifiers: OID:2.16.840.1.113883.4.642.40.97.42.79

When defining additional resources, this extension allows the relevant work group to indicate and approve that a core element (or another additional resource) may refer to the resource. This enables normal Reference.reference in deployments where both the core and additional resource definitions are in scope.

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 Specification

You can also check for usages in the FHIR IG Statistics

Changes since version 5.3.0:

  • New Content

    • 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

    Complex Extension: When defining additional resources, this extension allows the relevant work group to indicate and approve that a core element (or another additional resource) may refer to the resource. This enables normal Reference.reference in deployments where both the core and additional resource definitions are in scope.

    • profile: code: Name of the approved FHIR resource (including additional and historical resource names) that contains the declared reference element.
    • elementId: string: ElementDefinition id or path that identifies the reference element approved to target this additional resource.

    Maturity: 1

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: doco
    Extension 0..* Extension Allowed reference targets for an additional resource
    Extension.Slices for extension Content/Rules for all slices
    Extension.Slices for extension.extension:target 1..* Extension A reference element that may target this additional resource
    Extension.Slices for extension.extension:target.extension 2..2 Extension Extension
    Extension.Slices for extension.extension:target.Slices for extension Content/Rules for all slices
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile 1..1 Extension Name of the approved resource that contains the reference element
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.extension 0..0 Extension
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.url 1..1 uri "profile"
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.value[x] 1..1 code Value of extension
    Binding: extended-resource-types (??) (required): Current and past FHIR resource types (deleted or renamed), and additional resource types (FHIR v6.0.0-ballot4).
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId 1..1 Extension ElementDefinition id/path of the reference element
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.extension 0..0 Extension
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.url 1..1 uri "elementId"
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.value[x] 1..1 string Value of extension
    Extension.Slices for extension.extension:target.url 1..1 uri "target"
    Extension.Slices for extension.extension:target.value[x] 0..0 Value of extension
    Extension.url 1..1 uri "http://hl7.org/fhir/StructureDefinition/additional-resource-reference-target"
    Extension.value[x] 0..0 Value of extension

    doco Documentation for this format
    NameFlagsCard.TypeDescription & Constraints    Filter: doco
    Extension 0..* Extension Allowed reference targets for an additional resource
    Extension.id 0..1 id Unique id for inter-element referencing
    Extension.Slices for extension 1..* Extension Additional content defined by implementations
    Slice: Unordered, Open by value:url
    Extension.Slices for extension.extension:target 1..* Extension A reference element that may target this additional resource
    Extension.Slices for extension.extension:target.id 0..1 id Unique id for inter-element referencing
    Extension.Slices for extension.extension:target.Slices for extension 2..2 Extension Extension
    Slice: Unordered, Open by value:url

    Slicing Note: The rules on this element (including its children) apply to all the slices, but are not repeated in them
    Extension.Slices for extension.extension:target.Slices for extension Content/Rules for all slices
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile 1..1 Extension Name of the approved resource that contains the reference element
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.id 0..1 id Unique id for inter-element referencing
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.extension 0..0 Extension
    Slice: Unordered, Open by value:url

    Slicing Note: The rules on this element (including its children) apply to all the slices, but are not repeated in them
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.url 1..1 uri "profile"
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.value[x] 1..1 code Value of extension
    Binding: extended-resource-types (??) (required): Current and past FHIR resource types (deleted or renamed), and additional resource types (FHIR v6.0.0-ballot4).
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId 1..1 Extension ElementDefinition id/path of the reference element
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.id 0..1 id Unique id for inter-element referencing
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.extension 0..0 Extension
    Slice: Unordered, Open by value:url

    Slicing Note: The rules on this element (including its children) apply to all the slices, but are not repeated in them
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.url 1..1 uri "elementId"
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.value[x] 1..1 string Value of extension
    Extension.Slices for extension.extension:target.url 1..1 uri "target"
    Extension.url 1..1 uri "http://hl7.org/fhir/StructureDefinition/additional-resource-reference-target"

    doco Documentation for this format

    This structure is derived from Extension

    Summary

    Complex Extension: When defining additional resources, this extension allows the relevant work group to indicate and approve that a core element (or another additional resource) may refer to the resource. This enables normal Reference.reference in deployments where both the core and additional resource definitions are in scope.

    • profile: code: Name of the approved FHIR resource (including additional and historical resource names) that contains the declared reference element.
    • elementId: string: ElementDefinition id or path that identifies the reference element approved to target this additional resource.

    Maturity: 1

    Differential View

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: doco
    Extension 0..* Extension Allowed reference targets for an additional resource
    Extension.Slices for extension Content/Rules for all slices
    Extension.Slices for extension.extension:target 1..* Extension A reference element that may target this additional resource
    Extension.Slices for extension.extension:target.extension 2..2 Extension Extension
    Extension.Slices for extension.extension:target.Slices for extension Content/Rules for all slices
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile 1..1 Extension Name of the approved resource that contains the reference element
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.extension 0..0 Extension
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.url 1..1 uri "profile"
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.value[x] 1..1 code Value of extension
    Binding: extended-resource-types (??) (required): Current and past FHIR resource types (deleted or renamed), and additional resource types (FHIR v6.0.0-ballot4).
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId 1..1 Extension ElementDefinition id/path of the reference element
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.extension 0..0 Extension
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.url 1..1 uri "elementId"
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.value[x] 1..1 string Value of extension
    Extension.Slices for extension.extension:target.url 1..1 uri "target"
    Extension.Slices for extension.extension:target.value[x] 0..0 Value of extension
    Extension.url 1..1 uri "http://hl7.org/fhir/StructureDefinition/additional-resource-reference-target"
    Extension.value[x] 0..0 Value of extension

    doco Documentation for this format

    Snapshot View

    NameFlagsCard.TypeDescription & Constraints    Filter: doco
    Extension 0..* Extension Allowed reference targets for an additional resource
    Extension.id 0..1 id Unique id for inter-element referencing
    Extension.Slices for extension 1..* Extension Additional content defined by implementations
    Slice: Unordered, Open by value:url
    Extension.Slices for extension.extension:target 1..* Extension A reference element that may target this additional resource
    Extension.Slices for extension.extension:target.id 0..1 id Unique id for inter-element referencing
    Extension.Slices for extension.extension:target.Slices for extension 2..2 Extension Extension
    Slice: Unordered, Open by value:url

    Slicing Note: The rules on this element (including its children) apply to all the slices, but are not repeated in them
    Extension.Slices for extension.extension:target.Slices for extension Content/Rules for all slices
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile 1..1 Extension Name of the approved resource that contains the reference element
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.id 0..1 id Unique id for inter-element referencing
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.extension 0..0 Extension
    Slice: Unordered, Open by value:url

    Slicing Note: The rules on this element (including its children) apply to all the slices, but are not repeated in them
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.url 1..1 uri "profile"
    Extension.Slices for extension.extension:target.Slices for extension.extension:profile.value[x] 1..1 code Value of extension
    Binding: extended-resource-types (??) (required): Current and past FHIR resource types (deleted or renamed), and additional resource types (FHIR v6.0.0-ballot4).
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId 1..1 Extension ElementDefinition id/path of the reference element
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.id 0..1 id Unique id for inter-element referencing
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.extension 0..0 Extension
    Slice: Unordered, Open by value:url

    Slicing Note: The rules on this element (including its children) apply to all the slices, but are not repeated in them
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.url 1..1 uri "elementId"
    Extension.Slices for extension.extension:target.Slices for extension.extension:elementId.value[x] 1..1 string Value of extension
    Extension.Slices for extension.extension:target.url 1..1 uri "target"
    Extension.url 1..1 uri "http://hl7.org/fhir/StructureDefinition/additional-resource-reference-target"

    doco Documentation for this format

     

    Other representations of profile: CSV, Excel, Schematron

    Terminology Bindings

    Path Status Usage ValueSet Version Source
    Extension.extension:target.​extension:profile.value[x] Base required http://hl7.org/fhir/ValueSet/extended-resource-types Not State Unknown

    Constraints

    Id Grade Path(s) Description Expression
    ele-1 error **ALL** elements All FHIR elements must have a @value or children hasValue() or (children().count() > id.count())
    ext-1 error **ALL** extensions Must 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)