description: Extension on Observation.value[x] to add data type Reference. package_name: nictiz.fhir.nl.stu3.geboortezorg derivation: constraint name: bc-observation-valuereference type: Extension elements: url: pattern: {type: Uri, value: 'http://nictiz.nl/fhir/StructureDefinition/bc-observation-valuereference'} index: 0 valueReference: type: Reference index: 1 slicing: slices: valueReference: match: {} schema: {type: Reference, index: 1} package_version: 1.3.3-rc3 class: extension kind: complex-type url: http://nictiz.nl/fhir/StructureDefinition/bc-observation-valuereference base: http://hl7.org/fhir/StructureDefinition/Extension version: null