Called Vertigo because you don't reach dizzy heights, and you find your fit at the 2 level.
I was looking for a method that could show both single suited and two suited hands, enable the fit to be found at the 2 level in the majority of instances, and yet distinguish in a 2 suiter whether the shown major is a 4 card or a 5 card suit. I also wanted to identify both the major and the minor before passing the level of 2 of the major.
This is it. It has been enabled by a long overdue relaxation of the EBU rules, that now belatedly allow a double to have any meaning (level 3 and above). With everybody having wriggles available, double rarely leads to a good score, and the frequency of wanting a penalty is far less than that of wanting to compete - and frequency is paramount, especially in pairs scoring.
The same defence is played in all seats to all strength no trumps.
In a direct overcall the strength is up to you, but for safety as well as constructivity have your minimum one point less than their minimum. As the strong NT is much more useful than the weak NT in enabling them to have a constructive auction, you may choose to forgo safety and play it disruptively, weaker.
In protective position the strength can be anything you like, as the points are known to be shared pretty equally.
2NT = 5/5 in the minors.
2 Major = single suited in that suit.
2 minor = that minor + a 5 card major.
Partner passes the minor, or bids hearts if 2/3 card suit.
Any other bid bid by partner is to play.
Over a heart reply, overcaller passes with hearts, else bids spades.
Over a spade reply, overcaller passes with spades, rebids a long minor, or bids 2NT if he has at least a doubleton in the other minor, to allow partner (who may have the other minor) to choose the best contract.
X = all other 2-suiters
so this has to be a 4 card major plus any 5 card suit (may be the other major), or both majors.
The responses to the 'X' show or deny a 4 card major, and overcaller's rebids are natural.
Partner bids 2 if he has no 4 card major
Overcaller passes with 5 clubs,
else overcaller bids 2♦ with 5 diamonds
Partner passes or bids 2♥ if he prefers a 4/3 major fit - for pass or correct
else overcaller bids 2♥ with 5 hearts (and therefore 4 or 5 spades)
Partner can convert to spades if his spades are longer than hearts.
else overcaller bids 2♠ with 5 spades (and therefore 4 hearts)
Partner bids 2♦ if he has a 4 card spade suit but not 4 hearts ((2♦ shows ♠))
Overcaller bids 2 with spades, obviously
else overcaller passes with 5 diamonds
else overcaller bids 2♥ with 4 hearts and 5 clubs.
Partner bids 2♥ with a 4 card heart suit (he may also have spades)
Overcaller passes with hearts or bids 2♠
Partner over 2♠ passes or may bid 3 for pass or correct to the 5 card minor.
(Memory reminder - over the X, 2 = no 4 card major, 2♦ shows spades.)
With most of these 2-suited sequences, partner can discover the minor before getting over the level of 2 of the major, and in many cases is able to play in 2 of the minor when he knows there is no major fit.
Warning - this use of the double to mean either a 5 card minor and or 4 card major, or both majors, is a fun bid that gets many good results, but beware that 20% of the time ( with no good fit ) you can end up at the 3 level. You can avoid this if you wish by a safe variation of the defence that has X meaning nothing other than "both majors". BUT the key difference and benefit of this convention is that you always end up in the best major fit.
X = Both majors (5/5, 5/4, 4/5, maybe 4/4 if feeling frisky)
Partner bids her longer major, or if equal length bids 2♦ = no preference, and then the doubler bids his better or longer major. A fallback is that if partner HATES the majors, she can bid 2 for pass or correct to diamonds.
Alternatively you can arrange the showing of preference and the resolution to a major to always put the 1NT opener on lead, by using transfers. For example, with an immediate 2nd seat X, 4th seat bids 2 for equal length, and then doubler transfers to a major. With a 4th seat double, 2nd seat bids 2 for equal length, or transfers to the preferred major.
Other replies by advancer - invitations and signoffs
After a direct overcall, advancer can bid 2NT at any stage to show an invitational hand in NT.
Similarly, he can bid 3 of the major as an invitation.
If advancer at any time bids anything else other than the system bids above, then this is a natural suit to play.
Coping with interference when the responder to 1NT bids - a suggestion
The one system bid is essentially a negative or takeout double.
(1NT) 2/ ♦ (responder X)
ignore the double, bid as above.
(1NT) 2/ ♦ (responder bids a major)
Bid the known minor with a fit, and 'X' = fair hand with support for the other major. Overcaller passes with the opposition major.
(1NT) X (XX)
ignore the redouble, bid as above.
(1NT) X (they bid a transfer to major, or natural major)
'X' = 4+ cards in the major responder is not showing.
(1NT) X (they bid a minor, natural)
'X' = a four card major AND the other minor
or a four card major strong enough for 2NT
or both 4 card majors.
Overcaller bids 2♥ if he has them, and you can pass or convert to spades, whereupon overcaller can pass spades if he has them or bids the other minor.
Otherwise overcaller bids 2♠ (with no hearts) and you pass or bid the other minor.
After interference from responder, if advancer makes any bid other than double or the shown major, then this is natural, to play.
submitted by Ray Green