> Playing in the Regional last week, my partner and I had a disagreement
> about this sequence:
> 2NT-3H; 3S-5NT.
> (3H is a transfer to spades.)
> How does the group feel this ought to be played?
That depends on the rest of your agreements. If you have a way of
forcing spades to be trumps (e.g. by a (South African) Texas Transfer)
then you don't need to play this as grand slam force, because you can
agree spades and then jump to 5NT.
If you have no way to set spades as trumps, it's probably grand slam
force asking for top spade honours.
As I have a way of making spades trumps, I play it in the (probably
somewhat old-fashioned) traditional way. 2NT-5NT says "I am forcing
to 6NT and inviting 7NT if you are maximum", so 2NT-3H-3S-5NT says "I
am forcing to small slam, happy to play in 6NT, and interested in 7S/
7NT if you are maximum, and by the way I have 5 sapdes so look at your
spade holding"
The alternative meaning is choice of slam, offering 6S or 6NT.
Personally I don't like this, because I think it's very rare to have a
hand that knows it wants to play exactly at the 6-level without
investigating alternative levels. However, I think that would be a
very popular meaning particularly in the ACBL where 5NT seems always
to be 'choice of slams'.