4♠ went one down after a heart lead.
Assume that the written agreement is hearts + diamonds, East misbid thinking that it showed hearts + clubs, and West fielded the misbid (see edit below). As I understand it, in the EBU the director would award an artificial score of 60-40 (or possibly less for the offending side), because there was a concealed implicit agreement that 2♥ showed hearts and a minor.
If NS had received the correct explanation, the auction, play and result would have been exactly the same. If I were king for a day, the table result would stand, and EW would receive a procedural penalty for having a CPU.
In the EBU, NS get an underserved 60%.
Edit: For the purpose of this discussion, assume that at the end of the hand West said "I would have bid 5♦, but I didn't believe he had diamonds - he often gets our two-suited agreements wrong."
This post has been edited by gnasher: 2012-July-25, 04:19