As stated by section 6.3.18 Limiting Distributed Operations of the NGSI-LD API...

As stated by section 6.3.18 Limiting Distributed Operations of the NGSI-LD API v1.8.1 specification, the Registry API operations are always local and thus are not included. This section also add a new clause for including the HTTP Via Header (IETF RFC 7230) for all the operations over the endpoints /entities/, /types/, /attributes/, /subscriptions/, /csourceSubscriptions/, /entityOperations/, /temporal/entities/ and temporal/entityOperations/.