What tolerances do those august (money-making) bodies allow, Neil?
And what techniques do they
use to weigh the weights before issuing any certificate(s)?
Also, where are test weights tested, and how are they transported etc.
But anyway (and more importantly), what tolerances are permitted clinically for patient weighing scales?
Bearing in mind that, wherever you are in the world (and as mentioned a few time before), 1 litre of water weighs 1 kg. 1 litre of pure water at 4 °C weighs 1 kilogram.