Printing non-significant figures

[josephwright]

[Anonymous report]

In successive calculations, non-significant figures are not rounded but often printed as subscripts. It would be nice if the output

$5.67_{89}(12_{34})$

can be got with the input

\num{5.67_89+-0.12_34}

[josephwright]

From an e-mail

I think this notation is common in analytical chemistry. I have read two textbooks on analytical chemistry ("Analytical Chemistry" by G.D. Christian, and "Quantitative Chemical Analysis" by D.C. Harris) and both of them recommend that non-significant figures should not be rounded in successive calculations and that they should be printed as subscripts. I found this notation also in a handbook of chemistry ("Kagaku Benran" by Chemical Society of Japan).