Do you know, że… ?
The direction vector is used in many modeling areas, verification or strength calculations.
By default, a direction vector can be something linear, e.g. sketch line, edge, axis (or a temporary axis) and the plane. In the case of the latter, the direction is the vector perpendicular to this plane.
It turns out, that the direction vector w Extruded Boss / Cut you can define by picking two points.
Or an example with the coordinate system below.