description: Defines the additional constraints and extensions on the UK Core Observation Vital Signs profile, for recording the clinical observation of a patients head circumference. package_name: fhir.r4.ukcore.stu3.currentbuild derivation: constraint name: UKCoreObservationVitalSignsHeadCircumference type: Observation elements: code: binding: {strength: preferred, valueSet: 'https://fhir.hl7.org.uk/ValueSet/UKCore-HeadCircumferenceMeasurements'} index: 0 value: choices: [valueQuantity] index: 2 valueQuantity: {type: Quantity, choiceOf: value, index: 3} value[x]: elements: unit: pattern: {type: String, value: centimeter} index: 4 system: pattern: {type: Uri, value: 'http://unitsofmeasure.org'} index: 5 code: pattern: {type: Code, value: cm} index: 6 package_version: 0.28.0-pre-release class: profile kind: resource url: https://fhir.hl7.org.uk/StructureDefinition/UKCore-Observation-VitalSigns-HeadCircumference base: https://fhir.hl7.org.uk/StructureDefinition/UKCore-Observation-VitalSigns version: 0.1.1 required: [value, valueQuantity]