The Milk Marketing Board (MMB) specification for milk yield recording defines the acceptable limits of error for any recording equipment whether manual or automatic. This is that at any milking 95 per cent of the measurements must not deviate more than ± 5 per cent or 0.25 kg (whichever is the greater) from the true weight. Hence an error of ± 0.25 kg is allowable for yields below 5 kg and 5 per cent of yield for quantities greater than 5 kg.