description: If the value is not a proper value, indicates the reason. package_name: rs/hl7.fhir.r2b.core derivation: constraint name: NI | OTH | NINF | PINF | UNK | ASKU | NAV | NASK | TRC | MSK | NA | QS type: null elements: extension: isModifier: false name: extension mustSupport: false maxLength: 0 base: {max: '0', min: 0, path: Extension.extension} isSummary: false index: 0 url: isModifier: false pattern: {type: uri, value: 'http://hl7.org/fhir/StructureDefinition/iso21090-nullFlavor'} type: uri mustSupport: false maxLength: 0 base: {max: '1', min: 0, path: Extension.url} isSummary: false index: 1 value: isModifier: false mustSupport: false choices: [valueCode] maxLength: 0 base: {max: '1', min: 0, path: 'Extension.value[x]'} isSummary: false index: 3 valueCode: isModifier: false index: 4 type: code mustSupport: false maxLength: 0 base: {max: '1', min: 0, path: 'Extension.value[x]'} choiceOf: value isSummary: false package_version: 1.4.0 extensions: {} class: datatype kind: datatype url: http://hl7.org/fhir/StructureDefinition/iso21090-nullFlavor base: http://hl7.org/fhir/StructureDefinition/Extension version: null required: [value, valueCode]