ANTI is a competitive action after the opponents have opened 1NT (balanced).

The ANTI bids are generally designed to show a competitive hand (more shape than points) with either a one-suited or a two-suited holding (usually 5-5) by the intervenor.  The origin of this conventional method is unknown.

The advancer is the partner of the intervenor.

- 1NT, Dble: intended as penalty showing 16+HCP and Advancer would normally pass.  However, if Advancer must bid then it should be 'System On' as if partner opened 1NT (i.e. Stayman, Transfers or any other agree mechanism should be used).

- 1NT, 2♣ : either a 6-card Diamond suit or 2-suited in the Majors (this could be 5-4).  Advancer would normally bid 2♦ (anchor) as 'Pass or correct', the intervenor can then bid 2♥ with both Majors.

- 1NT, 2♦ : either a 6-card Heart suit or 2-suited in Spades and an unspecified Minor.  Advancer would normally bid 2♥ (anchor) as 'Pass or correct', the intervenor can then bid 2♠ with the Spades and Minor holding.

- 1NT, 2♥ : 2-suited in Hearts and an unspecified Minor.  Advancer would normally pass or bid 3♣ as 'Pass or correct'.

- 1NT, 2♠ : 6-card Spade suit.  Advancer would normally pass.

- 1NT, 2NT: 2-suited in Minors.  Advancer would normally bid the better Minor fit.

NOTE:  The intention of this convention is to distrupt the opponents 1NT and find a reasonable part-score contract.  Therefore, the advancer would normally bid the 'anchor' suit or pass.  However, with a good hand and interest in game the Advancer can break step and 'enquire' with 2NT.