- after 1♣, 2NT shows ♦s and ♥s;
- after 1♦, 2NT shows ♣s and ♥s;
- after 1♥ or 1♠, 2NT shows the minors, ♣s and ♦s.
With a two-suited hand outside the agreed strength, make a simple overcall.
This convention also works at higher levels. In general, a surprise NT overcall at a high level shows 5-5 in the lowest two unbid suits, if followed by correction, some other two-suiters.
When faced with a 2NT overcall promising two known suits, many pairs take advantage of the fact using one cuebid to show a forcing raise of the opener suit, and the other cuebid to show a forcing bid of the fourth suit. Bidding those suits directly instead are merely competitive calls.