description: 'DSTU2: `DeviceUseStatement.whenUsed` (new:Period)' package_name: hl7.fhir.uv.xver-r2.r4 derivation: constraint name: ExtensionDeviceUseStatement_WhenUsed type: Extension elements: url: base: {max: '1', min: 1, path: Extension.url} pattern: {type: Uri, value: 'http://hl7.org/fhir/1.0/StructureDefinition/extension-DeviceUseStatement.whenUsed'} index: 0 value: base: {max: '1', min: 0, path: 'Extension.value[x]'} choices: [valuePeriod] index: 2 valuePeriod: base: {max: '1', min: 0, path: 'Extension.value[x]'} type: Period choiceOf: value index: 3 package_version: 0.1.0 class: extension kind: complex-type url: http://hl7.org/fhir/1.0/StructureDefinition/extension-DeviceUseStatement.whenUsed base: http://hl7.org/fhir/StructureDefinition/Extension|4.0.1 version: 0.1.0 required: [url]