Developed by Mr. George Rosenkranz as a feature of the Romex System, and an opening which has become fundamental in the Romex System. The problem was that a hand containing 18/19-20/21 high card points could be opened with a Dynamic 1 No Trump, showing a balanced holding with six controls or a holding just short of the requirements for a strong artificial 2 Clubs opening.

On the other hand, a holding with 19-20 high card points, balanced, and with a range of 4-6 losers and possibly a 5-card Major suit did not fall into this category of a Dynamic 1 No Trump opening. Therefore, the creation of a 2 Diamonds opening to show such a holding. Source is The Official Encyclopedia of Bridge, 1997.

The following holding contains 21 high card points and 6 controls. Open 1 No Trump as a Dynamic 1 No Trump.

The following holding contains 20 high card points and at least 6 losers. Open 2 Diamonds using Mexican Two Diamonds.

Responses:

1. a Negative Response with 0-4 points is pass with Diamond support.

2. a 2 Hearts response transfers the opener to 2 Spades and the responder either passes the 2 Spade rebid, or signs off in a rebid of 3 Clubs or 3 Hearts, showing length in either of these two suits.

2.1. a 2 Hearts response may also be, upon partnership agreement, a semi-positive response showing 5-6 high card points.

3. a response of 2 Spades transfers the opener to 2 No Trump.

4. Positive Responses promise 7 high card points or more, and are considered game-forcing.

5. a Positive Response also includes the use of Texas Transfers, the purpose of which is to have the stronger hand concealed during the play, thus the responder transfers the opener to the intended suit by bidding the suit ranking lower than the intended suit. These transfer bids are used only when the partner realizes that he holds enough values for game or slam, not partscore. This difference is the fundamental key of the Texas Transfer convention.

5.1. a Positive Response of 2 Spades, showing 7-9 high card points and a balanced holding, transfers the opener to 2 No Trump.

5.2. a Positive Response of 2 No Trump shows 10 plus high card points and a balanced holding.

5.3. any Positive Response on the Three Level, even 3 Diamonds, promises at least 10 plus high card points and a broken 6-card suit.

In the Romex System, the high card requirements of the responder are decreased by 1 point for each 5-card suit and by 2 points for each 6-card suit. In the original version of the Romex System and the original version of the Mexican Two Diamond method, the requirements for the high card points were slightly lower than in the revised version, introduced in 1982, where the opener must have 23-24 high card points.

The Mexican Two Diamond bid is also an integral part of the Acol Bidding System, which means that the opener may have an Acol Two Bid in a Major suit or indeed a strong three-suited holding. The following auction will reveal the true holding.

Mexican Two Diamonds

There is a section on this convention included in the book Godfrey’s Stairway to the Stars, written by Mr. Phillip Alder and co-authored by Mr. George Rosenkranz, the inventor of the Mexican Two Diamonds convention. This section is also presented. Mr. Phillip Alder is also a Contributing Editor of the Official Encyclopedia of Bridge, 2001, in which the version above can be found.

Using the Romex System, any opening of Two Diamonds shows three possible types of holdings:

A: Point Range of 21-22 high card points, balanced holding, containing 7 controls. The holding may have a 5-card Major suit.

B: Point Range of 27-28 high card points, balanced holding, containing 9 controls. The holding may have a 5-card Major suit.

C: The third type is a game-forcing holding with the Primary Suit of Diamonds, or a one- or two-suited holding containing three or less Losing Tricks and generally seven or more controls.

Responses:

• Pass: Shows a holding with little values but long Diamonds.
• 2 : Shows 0-9 HCPs, no slam interest opposite 21-22 HCPs and balanced; generally less than 4 Hearts.
• 2 : Shows 10+ points, 3+ controls (in principle), and slam interest opposite 21-22 HCPs and balanced.
• 2 NT: Transfer to 3 ; normally indicates 0-3 points and 6 Clubs, but may be a Major two-suited holding.
• 3 : This bid is a special Stayman with 4 hearts (possibly 4-5 in both Majors) and game values only.
• 3 : Shows 5 plus Hearts, less than 4 Spades, 0-9 points; generally a sign-off or choice of games.
• 3 : Shows 5 plus Spades, 0-3 points; sign-off.
• 3 : Shows a strong distribution of 4-4-4-1 and 3 plus controls and slam interest.
• 3 NT: Shows a strong distribution of 4-4-4-1 and 3 plus controls and slam interest.
• 4 : Shows a strong distribution of 4-4-4-1 and 3 plus controls and slam interest.
• 4 : Shows a strong distribution of 4-4-4-1 and 3 plus controls and slam interest.

Notes:

The distribution 4-4-4-1 means exactly 4 Spades, 4 Hearts, 4 Diamonds and 1 Club.
The designation 4-5 in the Majors means exactly 4 Spades and 5 Hearts.

Mexican Two Diamonds at one time included a game forcing 4-4-4-1, with an unspecified singleton, but that hand pattern has been included in the Dynamic No Trump or the Romex Forcing Club.