The origin of this conventional method is unknown. The following information has graciously been contributed by Mr. Gerald Gregory of Devon, United Kingdom, as of May 2012.

Note: Mr. Gerald Gregory points out that the bridge player should not confuse this conventional method with the CRO conventional method, which is abbrieviated for Color-Rank-Other.

The defense method can be employed following the opening bid by the opposing side of a suit on the one level. The evaluation of the holding is generally based on the same parameters, upon which other, similar defense methods are based. The employment is dependent upon the state of vulnerability as is the normally required length of the two suits.

Note: The following example illustrates this defense method based on a partnership understanding that a Major suit opening promises at least a 5-card suit. If the approach is Acol-based, then the holding should generally not contain a 4-card Major suit for an opening bid on the one level.

East AQ74 KJ5 Q53 Q95		South 9 AQ872 AK974 76
1		2

East		South		Meaning
1				Promises opening values.
		2		Modified Wenble. The cuebid of the opening suit promises a two-suited holding with both suits of the same colour (C).
		Other Continuances over One of a Suit
		2 NT		Promises a two-suited holding of the same rank (R), namely Spades and Hearts, both Minor suits Clubs and Diamonds.
		3		Promises one black suit and one red suit (O). The options are: Spades and Hearts, or Spades and Diamonds, or Clubs and Hearts, or Clubs and Diamonds.

The first bid suit is the determining factor for the overcalls and the meanings of the overcalls. The meanings of the overcalls do not change. The following example shows this principle when the opening is 1 Heart.

East A10 AQ872 Q53 Q95		South 54 6 AK974 AQJ94
1		2 NT

East		South		Meaning
1				Promises opening values.
		2		Modified Wenble. The cuebid of the opening suit promises a two-suited holding with both suits of the same colour (C).
		Other Modified Wenble Continuances
		2 NT		Promises a two-suited holding of the same rank (R), namely Spades and Hearts, both Minor suits Clubs and Diamonds.
		3		Promises one black suit and one red suit (O). The options are: Spades and Hearts, or Spades and Diamonds, or Clubs and Hearts, or Clubs and Diamonds.

In the second example it is quite logical that the overcaller, with an overcall of 2 No Trump, holds Spades and Hearts, or suits of the same rank. This inferred information also applies to the overcall of 3 Clubs, which promises one black suit and one red suit. The overcaller will generally not have Hearts as one of the red suits, but rather Diamonds.

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.