# 1D parameters and datum points

Hello Tasa,

How I can type leveling standard? I need to put value of 1mm/km of 2mm/km
if you see picture there is oa, ob(sqr(d)) and oc(d) so in which area I need to put 1 or 2, or I need to put something else?

The distance depended uncertainties for leveling networks are denoted by σb. You should set σb = 1 mm (or σb = 2 mm) and σc = 0. Since JAG3D does not support σa = 0, you have to select a small number that does not effect the stochastic model, e.g., σa = 0.001 mm

if I want datum on all points I need to upload file only in datum points?

Yes, that is correct.

if I want for example datum on one point, I need to upload file with one point in datum points and file with rest of points in new points?

Yes, that is correct, too.

if is it correct for wat I can use reference points?

You can use reference points, if you have, for instance, some kind of official coordinates that should be fixed.

Kind regards
Micha

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