description: This cross-version extension represents AllergyIntolerance.reaction.certainty from http://hl7.org/fhir/StructureDefinition/AllergyIntolerance|1.0.2 for use in FHIR R4. package_name: hl7.fhir.uv.xver derivation: constraint name: Ext_R2_AllergyIntolerance_re_certainty type: Extension elements: url: base: {max: '1', min: 1, path: Extension.url} pattern: {type: Uri, value: 'http://hl7.org/fhir/1.0/StructureDefinition/extension-AllergyIntolerance.reaction.certainty'} index: 0 value: base: {max: '1', min: 0, path: 'Extension.value[x]'} short: unlikely | likely | confirmed - clinical certainty about the specific substance choices: [valueCode] index: 2 valueCode: base: {max: '1', min: 0, path: 'Extension.value[x]'} type: code short: unlikely | likely | confirmed - clinical certainty about the specific substance choiceOf: value index: 3 package_version: r2.r4-0.0.1-snapshot-2 class: extension kind: complex-type url: http://hl7.org/fhir/1.0/StructureDefinition/extension-AllergyIntolerance.reaction.certainty base: http://hl7.org/fhir/StructureDefinition/Extension|4.0.1 version: 0.0.1-snapshot-2 required: [url]