description: A reference to a Library containing the formal logic used by the artifact. package_name: hl7.fhir.r5.examples derivation: constraint name: library type: Extension elements: extension: {index: 0} url: pattern: {type: Uri, value: 'http://hl7.org/fhir/StructureDefinition/cqf-library'} index: 1 value: choices: [valueCanonical] index: 3 valueCanonical: {type: canonical, choiceOf: value, index: 4} package_version: 4.5.0 extensions: {} class: extension kind: complex-type url: http://hl7.org/fhir/StructureDefinition/cqf-library base: http://hl7.org/fhir/StructureDefinition/Extension version: 4.5.0 required: [valueCanonical, value]