A MODIFIED MONTREAL RELAY
The 2NT Opening Bid


2NT     Our opening bid of 2 takes care of balanced hands with 18-20 points and we can open 2 and then rebid 2NT with stronger hands, so we really do not need this bid for its general meaning of 20-21 points and balanced.

Use the call for anything you wish, but this is the recommended treatment:


2-Suited With Both Majors - 10+ Points
Yes, you could open with as few as 10 points but since you are going to play at the 3-level you should be cautious about hands with 11-13 points.  That said, there are a few such hands that have better distribution, such as 6-5 or 6-6, that you prefer to open immediately.  Use 2NT to describe these hands with one bid.  (This is a legal treatment on the ACBL General Convention Chart.)
NOTE: If you have the minimum point-count of only 10 points, all of them should be in the two majors.

The point-count can be higher than the 18 points needed for a 2 opening bid because after partner bids his best major you can bid again, as appropiate.

Responses
Responder can bid either major at the 3-level or the 4-level as a non-forcing bid.

If responder bids 3, the lower minor, it shows a strong hand in support of hearts, the lower major.

If responder bids 3, the higher minor, it shows a strong hand in support of spades, the higher major.

After a strong response by partner the opener has the option of several rebids.
  • Jump to game with a minimum hand
  • Rebid the agreed suit with a moderate hand
  • Rebid 3NT, which is Blackwood
  • Rebid the other major, showing the ace and a good hand
  • Rebid a minor, showing either the ace or a void, and a good hand
See the chapters on Baby Blackwood   and   MSK Blackwood