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: Code Options

Official URL: http://hl7.org/fhir/StructureDefinition/codeOptions Version: 5.4.0
Standards status: Trial-use Maturity Level: 1 Computable Name: CodeOptions
Other Identifiers: OID:2.16.840.1.113883.4.642.40.97.42.100

A logical reference (i.e. a reference to ValueSet.url) to a value set (and optionally a version) that identifies a set of possible coded values for the element. This extension is used to convey a list of candidate codes when there is no formal code in the code system already defined that captures the intended set. For example, the concept of COVID preventative medications could be expressed as a value set because there is no specific code representing that concept.

Context of Use

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

In addition, the extension can only be used when this FHIRPath expression is true:

ofType(CodeableConcept).coding.exists().not()

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:

  • No changes

    • 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 canonical: A logical reference (i.e. a reference to ValueSet.url) to a value set (and optionally a version) that identifies a set of possible coded values for the element. This extension is used to convey a list of candidate codes when there is no formal code in the code system already defined that captures the intended set. For example, the concept of COVID preventative medications could be expressed as a value set because there is no specific code representing that concept.

    Maturity: 1

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: doco
    Extension 0..1 Extension Url of a value set of activities
    Extension.extension 0..0 Extension
    Extension.url 1..1 uri "http://hl7.org/fhir/StructureDefinition/codeOptions"
    Extension.value[x] 1..1 canonical(ValueSet) Value of extension

    doco Documentation for this format
    NameFlagsCard.TypeDescription & Constraints    Filter: doco
    Extension 0..1 Extension Url of a value set of activities
    Extension.id 0..1 id Unique id for inter-element referencing
    Extension.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.url 1..1 uri "http://hl7.org/fhir/StructureDefinition/codeOptions"
    Extension.value[x] 1..1 canonical(ValueSet) Value of extension

    doco Documentation for this format

    This structure is derived from Extension

    Summary

    Simple Extension with the type canonical: A logical reference (i.e. a reference to ValueSet.url) to a value set (and optionally a version) that identifies a set of possible coded values for the element. This extension is used to convey a list of candidate codes when there is no formal code in the code system already defined that captures the intended set. For example, the concept of COVID preventative medications could be expressed as a value set because there is no specific code representing that concept.

    Maturity: 1

    Differential View

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: doco
    Extension 0..1 Extension Url of a value set of activities
    Extension.extension 0..0 Extension
    Extension.url 1..1 uri "http://hl7.org/fhir/StructureDefinition/codeOptions"
    Extension.value[x] 1..1 canonical(ValueSet) Value of extension

    doco Documentation for this format

    Snapshot View

    NameFlagsCard.TypeDescription & Constraints    Filter: doco
    Extension 0..1 Extension Url of a value set of activities
    Extension.id 0..1 id Unique id for inter-element referencing
    Extension.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.url 1..1 uri "http://hl7.org/fhir/StructureDefinition/codeOptions"
    Extension.value[x] 1..1 canonical(ValueSet) Value of extension

    doco Documentation for this format

     

    Other representations of profile: CSV, Excel, Schematron

    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 represented a little differently in R3:

    • Map the type canonical to uri on the element Extension.value[x]
    • Note: Extensions that have been modified for R3 are still draft while real-world experience is collected
    Name Flags Card. Type Description & Constraints      Filter: doco
    Extension 0..1 Extension Url of a value set of activities
    Extension. extension 0 .. 0 Extension
    Extension. url 1 .. 1 uri "http://hl7.org/fhir/StructureDefinition/codeOptions"
    Extension. value[x] 1.. 1 uri Value of extension

    doco Documentation for this format

    Search Parameters for this Extension

    (none found)