Nut slot depth?

Nut Action - nut slot height Critical measurement is distance of the bottom of the string from the 1st fret when in the nut slot That's the measurement related to actual nuts and bolts slot Nut Height Gauge - XYyY3y Nut Files

nut slot files You mean nut slots height ? With 3rd fret pressed, there should barely be any space over first fret Paper thin How to mark it ? The half