Coordinates -0.00

why sometimes rhino shows me the coordinates -0.00 instead of simply 0.00?

perhaps it’s not 0 exactly, like -0.000001 !

But I’ve drawn the point using Snap from 0.00 or sometimes projecting with Osnap to the plane…so the Snaps are not precise?

They are precise to a tolerance. Limitations inherent in the computer representation of numbers mean it is impossible to get absolute precision.

The difference is seldom something to worry about. It mostly has an impact if your geometry is very far from origin (search for that in the forum and you’ll find fuller explanation of the maths).