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. package_name: hl7.fhir.r5.core derivation: constraint name: allowed-type 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: 5.0.0-snapshot1 extensions: {} class: extension kind: complex-type url: http://hl7.org/fhir/StructureDefinition/operationdefinition-allowed-type base: http://hl7.org/fhir/StructureDefinition/Extension version: 5.0.0-snapshot1 required: [valueUri, value]