Blackwood Convention

4NT bid at any time (except after a direct raise from 1NT or 2NT) is asking partner for Aces.

Responses	Re-bids
5C with 0 or 4 Aces	6NT, 7NT or 4, 5, 6, 7 of the agreed trump suit which opener will pass, or 5NT which is asking for Kings on the same scale
5D with 1 Ace
5H with 2 Aces
5S with 3 Aces