description: A canonical URL for a StructureDefinition that this is derived from. This is a de-normalization of a chain of StructureDefinition.baseDefinition. package_name: hl7.fhir.core derivation: constraint name: StructureDefinition this is derived from type: Extension elements: extension: index: 0 slicing: slices: extension: match: {} schema: {index: 0} max: 0 url: type: uri pattern: {type: Uri, value: 'http://hl7.org/fhir/StructureDefinition/structuredefinition-ancestor'} index: 1 value: choices: [valueUri] index: 3 valueUri: {type: uri, choiceOf: value, index: 4} package_version: 1.8.0 extensions: extension: {url: null, max: 0, index: 0} class: extension kind: complex-type url: http://hl7.org/fhir/StructureDefinition/structuredefinition-ancestor base: http://hl7.org/fhir/StructureDefinition/Extension version: null required: [valueUri, value]