Always struck me as a bit illogical, that. After all, LHO might not have clubs, whereas RHO certainly has diamonds (indeed, playing the Walsh style that has become increasingly popular, the chances are that he has quite a lot of diamonds). Myself, I prefer to play that if an opponent bids a suit he might not have, then I have it when I bid it. If on the other hand an opponent bids a suit he certainly has, then I don't have it when I bid it. what I thought but with more detail :)