description: This cross-version extension represents Observation.subject from http://hl7.org/fhir/StructureDefinition/Observation|4.3.0 for use in FHIR R4.
package_name: hl7.fhir.uv.xver
derivation: constraint
name: Ext_R4B_Observation_subject
type: Extension
elements:
  url:
    base: {max: '1', min: 1, path: Extension.url}
    pattern: {type: Uri, value: 'http://hl7.org/fhir/4.3/StructureDefinition/extension-Observation.subject'}
    index: 0
  value:
    base: {max: '1', min: 0, path: 'Extension.value[x]'}
    short: Who and/or what the observation is about
    choices: [valueReference]
    index: 2
  valueReference:
    base: {max: '1', min: 0, path: 'Extension.value[x]'}
    type: Reference
    short: Who and/or what the observation is about
    choiceOf: value
    index: 3
package_version: r4b.r4-0.0.1-snapshot-2
class: extension
kind: complex-type
url: http://hl7.org/fhir/4.3/StructureDefinition/extension-Observation.subject
base: http://hl7.org/fhir/StructureDefinition/Extension|4.0.1
version: 0.0.1-snapshot-2
required: [url]