GrahamJson, on 2017-October-15, 04:34, said:
Yes, but which suit is which? At least two others think that diamonds is the eight card fit. As I said, I would bid 3H as I am not sure, however I don't think partner should suggest playing in a seven card diamond fit if he has a robust six card heart suit. So, does partner have, say, KJx KQJxx Axxx x or KJx KQJxxx Axx x? I think it should be the first, but I'm bidding 3H as it should be a playable contract with either hand opposite, whereas 3D might not be so comfortable with the second hand. Then again, 3NT looks like a pretty good contract with either hand, so perhaps Mr Bengtsson is correct.
if he had as much as either of those he wouldn't have made a non-forcing bid the previous round. if he didn't have enough to force and 4 diamonds, he would have bid 3 diamonds and waited for you to check for a spade stop with extras. in other words, he doesn't have 4 diamonds.
this isn't akin to, for example, (1s) x (p) where one will often bid 1NT rather than a suit so as to accurately show the point range. here partner's already shown a reasonable minimum point count by overcalling at the 2 level and 2NT doesn't show any extra, so partner's priority is showing shape and getting to the best partscore.