In the Brazil-Sweden match, 11 IMP's were gained by Brazil for finding this slam. The Brazilian auction was not entirely convincing to me, personally, but success is success.
2S(A/K/stiff/void)-P-2NT(not two top trumps)-P-
3H(two top hearts)-P-3S(A/K/stiff/void)-P-
At this point, to recap:
Opener has shown two top hearts, plus control of spades and clubs.
Responder has shown a top diamond plus a spade control.
No one has been able to make a Picture Jump.
Opener, however, has a monster opposite a GF. He clearly seems strong enough to make a serious move. The continuation:
With each side having control of each suit, Opener very strongly considers slam an option. However, he really doesn't have enough information himself. Plus, both partners know all that has been claimed so far; Opener need not take unilateral action because of what is known. Opener does know that he needs the heart Queen and more help in diamonds. So, a 4D LTTC call should work.
Responder, with both critical unknowns in the reds, must move. Because the heart situation is known by Responder, but not diamonds, 5D as Exclusion not being possible, Responder bids 5D asking for "key cards," the key cards being Aces and the missing diamond King.