The main concepts within versor are the coordinate system, the dimension, and the selection.
It may be helpful to think of the arrow keys as being two dimensions, “Major” and “Minor”; some of the documentation refers to them in these terms. The way that major and minor dimensions are related in versor is often analogous to the way they are related in their traditional use for cartesian coordinates: keeping going in the minor dimension unto you reach the end of a major dimension unit will take you into the next unit in the major dimension.