[bluejak]

Ok, vigfus, he has no other bid. What does he do next time the situation occurs? Will his partner recognise it and realise he may not have three cards? If so, do they not have a disclosable agreement?

[vigfus]

Now we have to consider partnership mutual understanding and table feeling.
There is no questinon that long term partnership tends to make them know each other behaviour and how the partner reacts in many situations, and this is almost impossible to rule it as UI. Here is an example.
East is an overbidder, West is an underbidder. They know that very well, but the opp's do not know that.
The bidding goes. Opp's always passing.
1♣ - 1♠ - 3♠ - ?
The 3♠ call has different meaning based on who made it.
When the underbidder makes the 3♠ call, the overbidder knows his partner holds maximum for his bid.
When the overbidder makes the 3♠ call, the underbidder knows his partner dose not hold maximum for his bid.
So - what does TD do now ?