http://hl7.org/fhir/StructureDefinition/elementdefinition-type-must-support|5.2.0

If true indicates that the specified type, profile or targetProfile must be supported by implementations.

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