description: When the base type is an abstract type (e.g. Resource or Element) then this extension defines which concrete types are allowed to be used for a parameter. In the absence of this extension, any type is allowed. Replaced by OperationDefinition.parameter.allowedType in R5+ package_name: hl7.fhir.uv.extensions derivation: constraint name: AllowedType type: Extension elements: extension: {index: 0} url: pattern: {type: Uri, value: 'http://hl7.org/fhir/StructureDefinition/operationdefinition-allowed-type'} index: 1 value: choices: [valueUri] index: 3 valueUri: {type: uri, choiceOf: value, index: 4} package_version: 5.2.0 extensions: {} class: extension kind: complex-type url: http://hl7.org/fhir/StructureDefinition/operationdefinition-allowed-type base: http://hl7.org/fhir/StructureDefinition/Extension version: 5.2.0 required: [valueUri, value]