There is a rule of 2, 3 and 4 established by Ely Culbertson for making opening pre-empts. However, it seems to give different opening bids to normal methods: caveat, as I understand it. For example, holding SAKQJxx Hxxx Dxx Cxx you have a 7 loser hand. With favourable vulnerabilty Culbertson's rule seems to suggest it can be opened 4S! Whereas, normal methods have us opening 2S as you would expect. What am I failing to understand? Or is it just a case of a different standard produces a different result?