I have a couple of technical questions regarding the 4 upper metal routing layers. I assume Metal Layers 2-5 are used for routing longer distances. Are there any conventions as far as the direction of run? Are 45 degree angles ever used? Or is it mostly that the tracks in one metal layer run Vertically...and the tracks in the next higher layer run Horizontally. What layers are the Ground and VDD normally run on? Finally, are there any DRC rules that pertain to adjacent layers. I fully expect that there are spacing rules between tracks running in the same layer. Thank You!