When selected, the above mentioned Rotate ... commands rotate the view about the axes of the Work Plane, by an angle equal to the View rotate step value.

When selected, the above mentioned Rotate ... commands rotate the view about the axes of the view projection plane (an orthogonal right-hand reference system based on a plane with its origin at the center of the current view, a horizontal x-axis pointing to the right, a vertical y-axis pointing to the top, and a z-axis pointing directly out from the screen), by an angle equal to the View rotate step value.