description: If the questionnaire-unit-open extension indicates that additional units other than the set of options provided for the question are allowed, this indicates the code system those units are expected to be drawn from.  This extension SHOULD be present on any question where questionnaire-unit-open allows additional coded values.
package_name: hl7.fhir.uv.sdc.r4b
derivation: constraint
name: UnitSupplementalSystem
type: Extension
elements:
  url:
    type: uri
    pattern: {type: Uri, value: 'http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-unitSupplementalSystem'}
    index: 0
  value:
    choices: [valueCanonical]
    index: 2
  valueCanonical: {type: canonical, choiceOf: value, index: 3}
package_version: 3.0.0
class: extension
kind: complex-type
url: http://hl7.org/fhir/uv/sdc/StructureDefinition/sdc-questionnaire-unitSupplementalSystem
base: http://hl7.org/fhir/StructureDefinition/Extension
version: 3.0.0
required: [valueCanonical, value]