description: An extra warning about the correct use of the value set. package_name: hl7.fhir.us.ecr derivation: constraint name: USPublicHealthUsageWarningExtension type: Extension elements: url: type: uri pattern: {type: Uri, value: 'http://hl7.org/fhir/us/ecr/StructureDefinition/us-ph-usagewarning-extension'} index: 0 value: choices: [valueString] index: 2 valueString: {type: string, choiceOf: value, index: 3} package_version: 2.1.1 class: extension kind: complex-type url: http://hl7.org/fhir/us/ecr/StructureDefinition/us-ph-usagewarning-extension base: http://hl7.org/fhir/StructureDefinition/Extension version: 2.1.1