A preview of his book is available on amazon and if you look at pages 24, 29, and 35 you can see how he describes it. Basically he sets up a scene, determines proper exposure on his camera, then inputs the aperture he wants to use into his flash and it tells him how far away from his subject to hold the flash (or vise versa). The "try it and adjust" method is what I use now too, but if I'm understanding what he's saying, it seems like a faster and more accurate way to do it