Opener shows 11-15 HCP (sometimes 10), 6 diamonds, and denies a 4 card major. Most sequences have analogs to the 2 Opener, except we don't need to find 4-4 major suit fits.

Basic Responses

2NT Asking Bid

Generally speaking, Responder's bids are natural except 4 is RKC for diamonds. Some exceptions:

After 2-2NT-3 showing a minimum with no 3 card major,

After 2-2NT-3 showing a minimum with one 3 card major, Responder's 3M shows a 5 card suit and is forcing to 3NT or 4.

After 2-2NT-3 denying hearts Responder's 3♠ is a 5 card suit forcing to 3NT or 4.

Interference

If the opponents interfere, we bid naturally, with X being negative.