http://hl7.org/fhir/StructureDefinition/consent-ResearchStudyContext|5.2.0

When a Research scope Consent, this is the specific research study that is allowed to use the information (or not).

element_id	types
Extension
Extension.extension
Extension.url
Extension.value[x]	Reference
Extension
Extension.id	http://hl7.org/fhirpath/System.String
Extension.extension	Extension
Extension.url	http://hl7.org/fhirpath/System.String
Extension.value[x]	Reference