Update a patient record, identified by an arbitrary label and its corresponding identifier value, from its JSON representation. If the user sending the request doesn't have the right to edit the target patient record, no change is performed and an error is returned. If the indicated patient record doesn't exist, however a valid JSON is provided with the query parameter "create" set to true, then a new patient record is created with the provided data; otherwise no change is performed and an error is returned. If multiple records exist with the same given identifier for the given label, no change is performed, and a list of links to each such record is returned. If a field is set in the patient record, but missing in the JSON, then that field is not changed.