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: Characteristic Expression

Official URL: http://hl7.org/fhir/StructureDefinition/characteristicExpression Version: 5.3.0-ballot-tc1
Standards status: Trial-use Maturity Level: 2 Computable Name: CharacteristicExpression
Other Identifiers: OID:2.16.840.1.113883.4.642.5.1557

An expression that defines the criteria for group membership. This extension can only be used on a Group resource with a membership of definitional. When this expression is used, the Group resource cannot have any characteristic elements; this mechanism is exclusive with characteristics. The result of the expression SHALL be boolean-valued. The expression SHALL be parameterized with a %context variable that represents the subject being tested for membership. If evaluation of the expression results in true, the subject is considered a member of the group.

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 Expression: An expression that defines the criteria for group membership. This extension can only be used on a Group resource with a membership of definitional. When this expression is used, the Group resource cannot have any characteristic elements; this mechanism is exclusive with characteristics. The result of the expression SHALL be boolean-valued. The expression SHALL be parameterized with a %context variable that represents the subject being tested for membership. If evaluation of the expression results in true, the subject is considered a member of the group.

    Maturity: 2

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..1 Extension Criteria for group membership
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/characteristicExpression"
    ... value[x] 1..1 Expression Value of extension

    doco Documentation for this format
    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..1 Extension Criteria for group membership
    ... id 0..1 id Unique id for inter-element referencing
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/characteristicExpression"

    doco Documentation for this format

    This structure is derived from Extension

    Summary

    Simple Extension with the type Expression: An expression that defines the criteria for group membership. This extension can only be used on a Group resource with a membership of definitional. When this expression is used, the Group resource cannot have any characteristic elements; this mechanism is exclusive with characteristics. The result of the expression SHALL be boolean-valued. The expression SHALL be parameterized with a %context variable that represents the subject being tested for membership. If evaluation of the expression results in true, the subject is considered a member of the group.

    Maturity: 2

    Differential View

    This structure is derived from Extension

    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..1 Extension Criteria for group membership
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/characteristicExpression"
    ... value[x] 1..1 Expression Value of extension

    doco Documentation for this format

    Snapshot View

    NameFlagsCard.TypeDescription & Constraints    Filter: Filtersdoco
    .. Extension 0..1 Extension Criteria for group membership
    ... id 0..1 id Unique id for inter-element referencing
    ... extension 0..0
    ... url 1..1 uri "http://hl7.org/fhir/StructureDefinition/characteristicExpression"

    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 represented a little differently in R3:

    • Replace the type Expression with a set of extensions for the content of the type along with the _datatype extension
    • Note: Extensions that have been modified for R3 are still draft while real-world experience is collected
    Name Flags Card. Type Description & Constraints      Filter: Filters doco
    . . Extension 0..1 Extension Criteria for group membership
    . . . Slices for extension 0 ..* Extension Extension
    Slice: Unordered, Open by value:url
    . . . . extension:_datatype 1..1 (Complex) DataType name 'Expression' from R5
    URL: http://hl7.org/fhir/StructureDefinition/_datatype
    . . . . . value[x] 1.. 1 string Value of extension
    Fixed Value: Expression
    . . . . extension:description 0..1 Extension Natural language description of the condition
    . . . . . extension 0 .. 0
    . . . . . url 1 .. 1 uri "description"
    . . . . . value[x] 1.. 1 string Value of extension
    . . . . extension:name 0..1 Extension Short name assigned to expression for reuse
    . . . . . extension 0 .. 0
    . . . . . url 1 .. 1 uri "name"
    . . . . . value[x] 1.. 1 code Value of extension
    . . . . extension:language 0..1 Extension text/cql | text/fhirpath | application/x-fhir-query | etc.
    . . . . . extension 0 .. 0
    . . . . . url 1 .. 1 uri "language"
    . . . . . value[x] 1.. 1 code Value of extension
    Binding: ExpressionLanguage ( extensible ) : The media type of the expression language.
    Additional Bindings Purpose
    MimeTypes Max Binding
    . . . . extension:expression 0..1 Extension Expression in specified language
    . . . . . extension 0 .. 0
    . . . . . url 1 .. 1 uri "expression"
    . . . . . value[x] 1.. 1 string Value of extension
    . . . . extension:reference 0..1 Extension Where the expression is found
    . . . . . extension 0 .. 0
    . . . . . url 1 .. 1 uri "reference"
    . . . . . value[x] 1.. 1 uri Value of extension
    . . . url 1 .. 1 uri "http://hl7.org/fhir/StructureDefinition/characteristicExpression"
    . . . value[x] 0 .. 0

    doco Documentation for this format

    Search Parameters for this Extension

    (none found)