description: This cross-version extension represents SubstanceSpecification.code.source from http://hl7.org/fhir/StructureDefinition/SubstanceSpecification|4.0.1 for use in FHIR R4B. package_name: hl7.fhir.uv.xver-r4.r4b derivation: constraint name: Ext_R4_SS_co_source type: Extension elements: url: base: {max: '1', min: 1, path: Extension.url} pattern: {type: Uri, value: 'http://hl7.org/fhir/4.0/StructureDefinition/extension-SubstanceSpecification.code.source'} index: 0 value: base: {max: '1', min: 0, path: 'Extension.value[x]'} short: Supporting literature choices: [valueReference] index: 2 valueReference: base: {max: '1', min: 0, path: 'Extension.value[x]'} type: Reference short: Supporting literature choiceOf: value index: 3 package_version: 0.0.1-snapshot-2 class: extension kind: complex-type url: http://hl7.org/fhir/4.0/StructureDefinition/extension-SubstanceSpecification.code.source base: http://hl7.org/fhir/StructureDefinition/Extension|4.3.0 version: 0.0.1-snapshot-2 required: [url]