When I measure the intonation point on the nut from the back of the first fret, you get a right-angled triangle with the caliper with a longer hypotenuse. By using Pythagoras theorem, I realize that you should add 0.05-0.1 mm to the measurement I got at the measurement, as the nut to be manufactured is always higher than the one mm that is the height of the fret piece.
Now I will measure as in the picture, or possibly cut down one of the tips of the caliper (have to think about that). The question is whether the small difference is audible. Not wrong to do it more right, anyway!