The Victoria Advocate – 26 Ago 2003
Lead: 
A
There are several ways to show a void when responding to Blackwood. But how can the ace-asker request responder to suppress the ace in a suit in which the asker holds a void?
The most popular method is known as exclusion Key-Card Blackwood, where the king of trumps counts as an ace: An unusual jump in a suit to the four or five level which cannot be natural asks for the number of controls partner holds outside the bid suit.
This example is from a tournament in Mexico City. As is the modern style, two clubs by North, a passed hand, was the Drury Convention, promising a better than minimum heart raise, and South’s two diamonds guaranteed a sound opening bid. When North continued with a spade cue-bid, South was on safe ground to confirm a real diamond suit — the agreed trump suit on this auction was hearts.
Having done the hand full justice, North retreated to three hearts. South now launched into exclusion Blackwood. Since four clubs would have been natural, the jump asked for key cards outside the club suit. North showed two and, with either an ace or the king of trumps missing, South settled in six hearts.
West led the ace of clubs and the hand was soon over. Declarer ruffed, trussed to the ace of diamonds and ran the jack of hearts. When that won, declarer repeated the finesse and claimed all the tricks when the king of hearts was proved to be with East and nothing bad happened in the trump suit.