1.2 million counts, so 20% overrange, but it is twitchy and sensitive to noise. You'll see the word 'Overload' a lot as it shifts ranges. If is averaging a noisy signal, it may shift down a range sooner than you'd think and may indicate 'Overload' even at much less than the full 1.2M counts. By 'error chart' do you mean a compilation of tolerances from the data sheet or from actual measurements of your unit?