An improved version of Blackwood, also known as Five Ace Blackwood, in which the king of trumps counts the same as an ace. The king of trumps and the four aces are all ‘key cards’. Replies to 4NT are almost the same as with ordinary Blackwood:
5♣ Zero or four key cards
5♦ One or five key cards
5♥ Two key cards
5♠ Three key cards
If there is a subsequent 5NT enquiry, the king of trumps does not count as a king but the queen of trumps does.