3rd suit forcing convention

The 3rd suit forcing
The 3rd suit forcing convention is a bid that the reponder uses on the 2nd round of bidding after the repetition by the opener, , of his opening suit at the 2 level.
Reminder :
When the opener has repeated his suit at the 2 level, any suit change by the responder (3rd suit then) is forcing. The opener's camp has the majority of the HCPIn general these suit changes by the responder on the 2nd round are natural, except in one specific sequence :

• Opening in a minor
• and a 2nd response in the suit just above (♦ if the opening was 1TR♣ and ♥ after 1 ♦).
  In that case, the 3rd suit bid is artificial : it guarantees neither length nor strength in that suit.
  This convention is only used after :
  • a minor opening
  • the repetition by the opener of his minor
  • the rebid by the reponder of a new suit 'chaeper' than his initial suit.
  It is stictly limited to the following sequences :
  1♣ - 1♥ -
  2♣ - ?
  1♣ - 1♠ -
  2♣ - ?
  1♦ -1♠ -
  2♦ - ?
  In all these cases the 3rd suit by the responder is not auto-forcing....in all other cases, it is auto-forcing.
  

Natural or artificial ?
To bid a 3rd suit forcing, the responder requires at least 11HL with no ipper limit. The opener has limited his hand by repeating his opening suit. A game is possible, if the opener is not minimum.In the 3 sequences covered by the convention convention, the bid of the 3rd suit by the responder can be :

• natural, ie showing a strength in the suit bid
• or artificial: the responder does not have a strength in the suit bid, but wants to continue the bidding

The rule issimple, If the 3rd suit bid is next to that bid by the opener, the bid is artificial, and guarantees nothing in the suit bid. In all the other cases, it is natural.

Strength and guarantees of the 3rd suit forcing convention
The responder uses this convention if he thinks a game is possible (with a minimum of 11HL) and

• does not have any other bid to show his strength
• wants to find 3 cards in his major in the opener's hand
• Wants to bid a differed fit in a sequence that is forcing
• Has a problem in this sui that prevents him from bidding NT
• Does not want to bid NT because he has no honors to protect

follow up bids by the opener after a 3rd suit forcing.
A great difference with the 4th suit forcing is that the 3rd suit forcing is not auto-forcing. The responder is allowed to pass after the opener's 3rd bid.
The opener must use a natural and forcing bid hif he wants to make sure that the sequence does not end.

• The priority of the opener is to show support if he has 3 cards in the responder's suit
• If not, he will bid NT,
  • If the 3rd suit is natural and he has a stopper in the unbid suit.
  • or if he has stoppers in both other suits
• Without stoppers in the suits concerned, and with a weak hand, he repeats his opening suit
• With a good opening, he can bid the 4th suit so that the responder becomes the declarer in 3NT