The NFL should really put out the guidance book on its rules that it gives to the refs... its way more informative than the regular rulebook, but they consider it a trade secret... once every few years a copy leaks out. I don't think I have seen one since pre 2010 though... they actively pursue that **** legally. they don't last online very long, but it does clarify how they tell the refs to call (or not call) every play and penalty... and some are dumb. for hardcore fans it would go a long way to clarifying what is and isn't called right... though maybe the lack of clarification is what the league ultimately wants.