Hi All, > I'm not clear what you mean when you refer to 'the e/A^3'. I think he means the numbers that coot displays, e.g. map 1 level = 1.56 e/A^3 (3.50 rmsd) So the answer to the question if the relation between the two numbers is linear is yes. > Yes '3 sigma' in this context is not correct: it's '3 RMSD', and indeed COOT > itself uses the latter terminology (which you see any time you change the > contour level), so I'm not clear where you got that from. In Coot docs it's called sigma or sigma-level: https://www2.mrc-lmb.cam.ac.uk/personal/pemsley/coot/web/docs/coot.html