http://hl7.org/fhir/StructureDefinition/operationdefinition-allowed-type|4.0.1

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.
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.
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: []
    index: 3
extensions: {}
class: extension
kind: complex-type
url: http://hl7.org/fhir/StructureDefinition/operationdefinition-allowed-type
base: http://hl7.org/fhir/StructureDefinition/Extension
version: 4.0.1
required: [value]