As a base for the entered data into the software application, Mr. E. Torbjörn Lindelof used the following opening bids, similar to the opening bids employed for the Schenken Club. They establish precise limits for each opening bid, but the system was so set up that the software could establish and adjust the point value of a certain holding according to its individual hand evaluation method.


Opening Bids Only

Bid Strength Meaning
1 : 16+ high card points Shows any shape.
1 : 11-15 high card points Shows a 3-card plus Diamond suit.
1 : 11-15 high card points Shows a 4-card plus Heart suit.
1 : 11-15 high card points Shows a 4-card plus Spade suit.
1 NT: 15-17 high card points Shows balanced shape.
2 : 11-15 high card points Shows a 5-card plus Club suit, or
  shows alternative preemptive Club suit.
2 : 23+ high card points Shows a balanced shape, or
  shows any game-forcing holding
2 : 9-12 high card points Shows 5-6 Hearts.
2 : 9-12 high card points Shows 5-6 Spades.
2NT: 11-15 high card points Distribution: 5-5 plus in two suits.

The computer software application was designed that after a 1 Club opening, any first response of 1 Diamond is an artificial negative bid and all other responses are considered to be natural. A first response in a Major suit is forcing for one round.


After 2 passes to Third Seat, by favorable vulnerability, the computer allowed for psychs with distributional holdings. Following a 2 Diamond opening, the responder shows controls: Aces, Kings, and also Queens.

If the opening is 2 No Trump, showing 11-15 high card points, and the first response is:

3 : Shows 0-3 high card points.
3 : Shows 4-7 high card points.
4 : Shows 8 plus high card points.

The opening bid requirements are established for First and Second Seat, but preempts in the Third Seat were allowed with as little as 7 high card points, since the hand evaluation method included counting 1 point for each card. Therefore, a 7-card suit equaled 7 points and would qualify for a Third Seat opening.

The Cobra computer system also allowed for competitive bidding and was based on the Law of Total Tricks. If an opponent opened with any 1 Club or 2 Clubs artificial bid, then a double shows a strong hand either in points or distribution.

A cuebid of the other opening bid suits is considered as a Takeout Double but also shows a void, yet to be determined, and a double of the opened bid suit indicates a singleton in that suit.

If the opponents are using a strong No Trump opening, 16-18 high card points, then all overcalls become natural on the next higher level and preemptive if higher.

If the opponents are using a weak No Trump opening, 12-14 high card points, then a competitive bid of 2 Clubs promises a 2-suited holding with one Major and one Minor suit; an overcall of 2 Diamonds promises both Major suits.

The designer also included many other features in his software program such as Optional Doubles after three-level bids, Takeout Doubles after a 4-level bid of a Minor suit and Penalty Doubles of any opening bid of 4 Hearts or higher.

Note: For a more in-depth clarification the student is directed to review the web page containing additional information about the Cobra Bidding System.



If you wish to include this feature, or any other feature, of the game of bridge in your partnership agreement, then please make certain that the concept is understood by both partners. Be aware whether or not the feature is alertable or not and whether an announcement should or must be made. Check with the governing body and/or the bridge district and/or the bridge unit prior to the game to establish the guidelines applied. Please include the particular feature on your convention card in order that your opponents are also aware of this feature during the bidding process, since this information must be made known to them according to the Laws of Duplicate Contract Bridge. We do not always include the procedure regarding Alerts and/or Announcements, since these regulations are changed and revised during time by the governing body. It is our intention only to present the information as concisely and as accurately as possible.