With reference to the attachment you provide, I have no idea what E2, F1 et al mean.
OK ... I've found something
It seems that Marsden
Note the ± 0.005% accuracy of the 5 kg M1 iron calibration weight (but note also the price)! This complies nicely with the attachment at Post #74654 (eg,
5 g at 100 kg - or 5 ml of water).