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.
typedestination
baseDefinitionhttp://hl7.org/fhir/StructureDefinition/Extension
typehttp://hl7.org/fhir/StructureDefinition/Extension
Extension.value[x].typehttp://hl7.org/fhir/StructureDefinition/Reference
Extension.value[x].targetProfilehttp://hl7.org/fhir/StructureDefinition/Resource