hrothgar, on 2014-June-11, 08:27, said:
The disagreement comes about when your response structure to the 1NT opening includes methods that explicitly show a singleton.
Your thought experiment should also include the following:
"Thanks for your ruling. You should also be aware that our response structure to 1NT openings includes bids that ask for singletons. How does this change your answer?"
You're going to get a VERY different answer to this question.
The GCC is a lot clearer about this: Any constructive rebid by opener is specifically allowed. And all calls after a natural 1NT are specifically allowed (with the exception for wide ranging or very weak 1NT openings).
I would never create an agreement for a hand type that occurs in 1% of the cases. But there cannot be any doubt that it is GCC legal.
Furthermore, just for the record since it is irrelevant, there is no indication that the NS pair in the OP uses a response structure that includes bids that ask for singletons. South transferred to spades and North refused the transfer which at best showed a singleton. South never used a bid that asked "Do you have a singleton?" and, though it wasn't stated explicitly, it seems clear that NS do not have a singleton asking bid.
Rik