Posted 2011-February-07, 12:26
In the ACBL:
1) PreAlerts are required for four classes of calls: non-GCC conventions, "Two-System" methods (explicitly not including variable NT ranges - we're talking "2/1 when you're NV, Precision when you are", or "K/S in 1 and 2, sound opening 2/1 in 3/4"), Very Light openings or preempts (VLP going away soon, replaced by Alert at time of call), and "systems fundamentally unfamiliar to the opponents" (i.e. canape, strong diamond, truly unfamiliar stuff). There is also one PreAlertable defensive agreement; leading small from xx.
2) Defences are explicitly Not Required for GCC-legal conventions. If the system or convention is fundamentally unfamiliar, then the PreAlert will allow the opponents to discuss a defence; but even then a defence need not be provided.
Having played a strong Club in the ACBL for years, I can guarantee that any legal defence to strong 1C is not considered "fundamentally unfamiliar" and does not require a PreAlert (hard to do so, anyway, after all, as the Strong Club is itself not PreAlertable). There's a reason my "defence to defences" notes are almost as long as my "first round responses" notes after 1C.
mrdct, you are correct that if they fail to PreAlert something PreAlertable, and as a result we are not allowed to create/use a defence, then they're cheating. You are not correct, however, at least in the ACBL, about what classifies as PreAlertable, nor about what is considered "you should know your defence to this."
When I go to sea, don't fear for me, Fear For The Storm -- Birdie and the Swansong (tSCoSI)