Normal is trace how it is.
Inverse is perpendicular negative. Meaning if you going to to right its down and vice versa. If it is going to the left will up and vice versa.
The the number going only 1 unit and the arrow between the units going either up or down or left or right is the direction going. 1 to the right then one up then one left.inverse Follow by one down then one to the right and one up. Repeating back to normal then inverse then normal. Normal inverse normal will turn direction of vectors that look like a square cup at the normal sequence. Including cubes.