http://hl7.org/fhir/StructureDefinition/flag-detail|5.2.0

Points to the Observation, AllergyIntolerance or other record that provides additional supporting information about this flag. Note that This extension will be replaced by Flag.supportingInfo in the FHIR R6 release.
element_idtypes
Extension
Extension.extension
Extension.url
Extension.value[x]
Extension
Extension.id
Extension.extension
Extension.url
Extension.value[x]