For UK operators CAP 789 Chapter 9 Paragraph 1.15 has some guidance namely:
1.15 Fuel Uplift Reconciliation
1.15.1 Operators are to ensure that the instructions for the refuelling of aircraft specifically require the commander to reconcile the initial fuel contents, and the known added fuel quantity as per the refueller's written records, with the total contents indicated by the aircraft's fuel gauge at the end of refuelling. If the uplifted fuel is not delivered through a calibrated meter, other means of confirmation such as a visual check of fuel contents will be necessary, which may require the aircraft to be shut down.
This guidance was introduced in FODCOM 01/08 to implement a recommendation addressed to the UK CAA by the Irish Air Accident Investigation Unit (AAIU) in response to a serious incident