[blml] Obviously this is the prime duty

[David Burn]

[SW]

Suppose NS play weak NT non-vul, strong NT vul.  South has 13 points and 
opens 1NT.  North (say in the ACBL or EBU) announces "15-17."  South 
looks up and to his horror (though he hides it well) sees that his side 
is vulnerable; North has given the correct explanation.

West passes, and North bids 2H, which is a transfer over a strong NT 
(and obviously what North intends) but natural and non-forcing over 
weak.  Should South announce "Transfer" (EBU/ACBL again) or keep quiet 
(natural non-forcing being non-alertable)?

I think there's a 100% clear answer to this, but to my surprise, not 
everyone seems to agree.

Of course South must _bid_ as if 2H is natural and non-forcing; I don't 
think there's any doubt about that under present interpretations.  The 
question is how South should _explain_ (and alert).

[DALB]

South should announce "transfer" (ACBL) or "spades" (EBU). He should then
pass.

I don't think this is a problem under either the dWS or the MS
interpretation. The problem with the dWS arises when South opens 1NT
vulnerable and hears North announce "13-15" (a misexplanation; North has
either forgotten the system or not noticed the vulnerability). Now North
bids 2H, which he intends as natural and non-forcing but which is
systemically a transfer. Per the MS South announces "transfer" or "spades"
(the correct description of the method, though an incorrect description of
the North hand) and bids 2S. Per the dWS South makes no announcement (the
wrong description of the method, though a correct description of the North
hand) and presumably bids 2S (but see below). 

Under the MS, the opponents at least know that South just has a strong no
trump. Under the dWS the opponents might conclude that South, who has
removed a sign-off in 2H to 2S, has: psyched 1NT; or bid 2S as a game try
with a super-maximum, heart support, and spade values; or opened 1NT with
five to 100 honours in spades and two low hearts; or...

But why should they have to guess? Or why should they have to ask? Why does
the dWS in effect force South to misrepresent his own hand, just because
North has misrepresented his? Why, in short, does the dWS exist at all?

Moreover, as I have pointed out elsewhere, according to Law and the MS South
must bid 2S, but according to the dWS he must not, because this is an
indication to North that a mistake has been made. I am still waiting for
Herman's answer to this, but I suspect I may have to wait a long time.

David Burn
London, England