description: 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.
package_name: hl7.fhir.uv.extensions.r4
derivation: constraint
name: CharacteristicExpression
type: Extension
elements:
  extension: {index: 0}
  url:
    pattern: {type: Uri, value: 'http://hl7.org/fhir/StructureDefinition/characteristicExpression'}
    index: 1
  value:
    choices: [valueExpression]
    index: 3
  valueExpression: {type: Expression, choiceOf: value, index: 4}
package_version: 5.1.0-ballot1
extensions: {}
class: extension
kind: complex-type
url: http://hl7.org/fhir/StructureDefinition/characteristicExpression
base: http://hl7.org/fhir/StructureDefinition/Extension
version: 5.1.0-ballot1
required: [valueExpression, value]