This conventional method was developed by Mr. Thomas Bigelow after Mr. Easley Blackwood developed and popularized the original Blackwood convention. The designation derives from the combination of the two words Culbertson and Blackwood, thus Culwood. This method is a variation based on a combination of the Culbertson Four-Five No Trump conventional method and the original Blackwood convention, which is an artificial bid asking for Aces. The Culwood convention is also a method of attempting slam based on the 4 No Trump bid by either partner.

Basic Principles of the Concept

The responses to the Culwood convention are identical to those of the Culbertson Four-Five No Trump, which are:

1.	Promises 3 Aces, which are not specified or identified,
2.	or 2 Aces in addition to the King of a real suit bid previously by one of the partners. This bid requests partner, at the same time, to show any Aces.

The designation real suit defines only a bid, which is natural, not artificial. The definition is important only when employing the Culbertson Four-Five No Trump convention when responding to the Ace-asking bid, since an artificial bid may have occurred in the auction before one partner has the opportunity to attempt slam with a 4 No Trump bid.

In contrast to the responses to the Culbertson Four-Five No Trump, the responses to the Culwood conventional 4 No Trump bid are more similar to the original concept as devised by Mr. Easley Blackwood and which were devised many years later. These responses to the Ace-asking bid are as follows and do not place any significance on or or they influenced by any previous bid, which may have been artificial.

5 :	Shows zero Aces.
5 :	Promises 1 Ace, the location of which is unspecified.
5 :	Promises 2 Aces, the location of which are unspecified.
5 :	Since the 4 No Trump Ace-asking bid has conveyed the information indicated above, the responder can communicate to partner that the partnership possesses all the Aces as well as the Kings of the previously bid suits. The 4 No Trump Ace-asking partner can then decided where to place the final contract and/or to inquire further regarding unknown Kings with a bid of 5 No Trump.
5 NT:	With this bid the responder guarantees that the partnership possesses all the Aces, and informs partner that his holding also contains two of the top three trump honors: Ace-King, Ace-Queen, or King-Queen.

As with the Culbertson Four-Five No Trump convention, the Culwood convention is also based on the fact that the partner bidding 4 No Trump to ask for Aces is also, at the same time, conveying information to partner about holding certain Aces and Kings. This feature is rather unique in the game of bridge and was developed by several of the most early pioneers of the game.

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.