[cencio]

Playing with wbridge ( a french software) i have seen that it open strong both with 2 c and with 2 d. The help file explain that 2 d is 24 or plus points, asking for aces.I would like to understand when to open with 2C or 2 D (what is the difference) and how to show the aces after the opening of 2 D

[apollo1201]

From my French experience

2C is strong undetermined but not GF: either strong 2 in any suit (above 20 or game -2 tricks with defense) or 22-23 balanced

2D is GF (24+ balanced or 1-2 suiters at game minus 1 trick and defense)

You answer 2H no ace and min; 2S 1 major ace, 2NT at least 2 K or 8 HCP and not too unbalanced, 3 C/D the ace of the suit. Then 3H/S/NT are 2 aces of same Color RAnk SHape. I even think 4x is 3 aces except the one of x and 4NT is 4 aces but you are probably facing KQJ in all 4 suits!

The ace answers are definitely not the strongest part of the system (e.g. 3D = I have the DA). It can help on very specific hands but it raises the bidding way too high on more common layouts where you cannot exchange a lot of information before 3NT.

Some ticked to 2S 1 ace and little outside; and 3C/D for a blac or red ace with at least 1K outside. Better but still not ideal.

2C GF with no ace answer (and 2D strong not GF) or 2C ambiguous either GF or strong with later distinction (2D at least positive, immediate 2H/S neg) do work better.

[pescetom]

The 2C version of this is called Crodo (invented by Pierre Albarran almost a century ago) and is still played by some older pairs in Italy (it was considered standard until ten years ago). Whenever an opponent announces it I am delighted and expect a good score, although it does occasionally hit the rather small target (or simply the slam is impossible to miss with any auction).