Developed by Alvin Landy. It's an interference convention over 1 NT opennings. Bidding 2 Clubs shows 5-5 major distribution with 12-14 points, or 5-4 distribution with 15-16 points or 4-4 distribution with 17+ points. 2nd opponent may pass only if he is very weak in majors and Clubs are long enough. Otherwise he should prefer one of the majors. If the lengths of majors are equal, he bids 2 Diamonds with a weak hand, 2 NT with a strong hand.
The other interferences are natural in this convention.