{description: How the type can be extended. Note that all FHIR types that inherit from ```Element``` have matchetype-mode = fhir-extensions, package_name: hl7.fhir.uv.tools.r5, name: MatchetypeMode, type: null, package_version: 0.4.0, class: unknown, kind: null, url: 'http://hl7.org/fhir/tools/CodeSystem/matchetype-mode', version: 0.4.0}