Since we're talking about the rear blocks, I believe that he's talking about the difference between inboard toe-in (where the arm is angled forward) and outboard toe-in (where the arm is pointed straight out) and the toe is gained from using optional blocks. The outboard toe-in allows the suspension to operate a little freer because the inner hinge pin does not have a sweeping load put on it. You also have to make sure that you check your track length when making the change from inboard toe to outboard toe.