from 12 -15 hp or 26-31 zp,

5+card major

Answers - undisturbed

• Pass : < 6hp

• 1♠ after 1♥ : NF,< 10+hp, sn♥  , 4+c ♠
• 1 NT : RF, the Duke convention for the 1M-opening. See also 'Strategy' in menu.
• 2♣ : RF, 10+hp, relay-bid, any distribution
• 2♦ : NF, <10hp, 4441,sn OM.
• 2AM : RF,10+hp, +5cAM, no 3c OM
• 2NT : 10-11hp, no 3c OM
• 3♣/♦/OM : JAZZ-raises :  a 4 card support in OM with
• (3♣ ) 9hp w/ 3+hp in OM,
• (3♦) 9hp w/ 0-2hp in OM,
• (3OM) 8hp

The continuation happens in a natural way, except for 1NT (see Duke below) and 2♣  (relay)

• 2♦ : min (12-13hp), 4+c minor, no 6 OM, no 4c AM
• 2AM : min ,4c AM
• 2OM : min, 6c OM
• 2NT : min, 5332 hand
• 3♣/♦  : max, 4c ♣/♦
• 3AM : max ,4c AM
• 3OM : max, 6c OM

The DUKE convention for a major opening

The partner who starts Duke -1NT- has a sn or void in OM, else he would have bid 2OM.

The opener must bid 2♣ unless he has a sn ♣ to avoid that partner would probably pass out.

With a 6 card in OM, the opener can bid 2OM willing to play in a 6-1 fit.

Also a 4 card AM is not let unbid in order to safeguard a possible -4 fit in AM.

Without a 6c OM, without a 4c AM, but with a sn♣ , the opener will bid 2♦.

After 2♣, with at least a 2c ♣, the partner shows the reason for his action :

• pass with a 5+ card ♣
• 2x with a 5+ card x
• 2NT with 10-11hp and a 2x5
• 3♣/♦  with 10-11hp and 5c ♣/♦  +  5c AM
• 2OM is very special : yet it seems that partner has a fit in OM. Because this strange road to show the fit, we agreed that partner has minimum a GF hand and opener must now start control bidding, inclusive sn's or voids.

(1) The sequence 1M-2♣-2♦ deserves special attention. Unlike the situation of a maximal answer where a 4 card minor can be named is here the id of the minor unknown. If required, the partner can investigate by bidding 2AM, an "impossible" bid to be natural understood. Indeed, a 4card AM is useless as opener has denied this. A 5card AM is also impossible because this would have  been bid directly. Ergo, 2AM conventionnally asks for the id of the minor. The answer is with steps and reveals more :

s12 =   ♣/♦ in a 54xx        s34 = ♣/♦ in a 5431 with a sn in am     s56 = ♣/♦ in a 5431 with a sn in  AM    s78 = ♣/♦ in a 56xx

(2) When opener holds a  4 card AM or 6 card OM, it is not unlikely to find a sn in that hand . Partner can investigate via 3♣. The answer iss via steps s1234 : no sn/ ♣/♦ /AM. 

     Also, after a 2/3 NT rebid (5332), partner can ask with 3/4♣  the id of the doubleton. Answer = s123 = ♣/♦ /AM.

(3) When a 1M opener rebids minimum  ( 2AM/OM) the partner knows enough to either pass or after 2AM go back to the OM suit or to bid the game contract. Therefore, if partner bids 3AM or 3OM, he shows slem ambition. The opener continues with controls.   

Also after a maximal answer (3-level) a game contract is sure. Not bidding that game contract shows slem ambition and starts up control bids.

Eg. 1M - 2♣

       3x - 3x+1  (or 4♣ after 3♠)

When  opponents overcall  1M

In general , we play SYSTEM OFF, continuing in a natural way.

Only after a double intervention,  we play TRUSCOTT :

2♣  becomes natural, NF,5 c♣ , sn OM

2NT = 10-11hp and 3+c  OM

Jazz raises remain valid.