Thanks for answer Micha, I appreciate it.

Now I want to ask same questions but for 2D.
If I want to put 2 + 2ppm for distance then I need to put in distance: in oa = 2 (mm)
, oc = 2 (ppm) and ob(sqr(d))=0? is it correct?

What I need to put for angle(direction), if I have instrument standard of 1'' - 0.31mgon, what to put in oa = (mgon), oc = (mm) and ob(sqr(d))= (mm)?

Also for example if I have 4(x, y) points can I put datum on point 1 (both X and Y) and on point 2 but to put datum only on Y? Is this possible?

Thanks,
Best regards.