Except as otherwise provided in any technical regulation, in the case of any weighing instrument provided with knife-edges and bearings, when the weighing instrument is loaded to one-half of its capacity, the load being centrally placed on or in the load receptor and, where applicable, also so placed on the pan for weights, any difference in the accuracy of the weighing instrument resulting from moving the knife-edges or bearings laterally within the limits of their movement must not exceed the value of the appropriate allowance of error at a load equal to one half of the capacity.