Here are the rules for Reverse Bergen Raises when your partner opens one of a major and you hold four card support:
10-12 HCP Limit raise Jump bid to 3
6-9 HCP Simple raise Jump bid to 3
0-5 HCP Preemptive raise Jump raise to three of the major
The reverse is in the meaning of the 3 clubs and 3 diamonds. Originally three clubs was a simple raise showing 6-9 HCP, but most players today agree that bidding three diamonds instead has more preemptive power. Also, using three clubs for the stronger raise provides extra bidding room if the opening bidder wants to use "Help Suit Game Try" and ask about diamonds.
Although this is the way other players use Reverse Bergen, my preference is to not have an upper limit on the 3
raise. See the paragraph
at the end of this essay.
These bids remove the old strong jump-shift by responder, but modern players prefer to have bids available for the more frequent hands such as those described above. These bids also follow the Principle of Fast Arrival, the idea that if you know where you are going, get there as fast as possible to preclude any action by the opponents. Of course, an immediate jump-shift in the other major is still available for whatever purpose the partnership wants to use, and some people are using it as a weak bid while others treat it as a strong jump. See the excellent discussion by Mike Savage where he describes strong jump shifts. Anyway, it's your choice.
So how does one handle a hand with only three card support and a limit raise? Part of the answer depends on whether or not you play a response of 1NT as forcing or not.
If 1NT is not forcing and partner opens the bidding with a major, then responder must bid a minor at the two level. It really doesn't matter which one, nor the length nor quality of the suit. (It's just to create a forcing auction.) The next bid will be a jump to the three level showing a limit raise but without four card support.
The majority of bridge players today play 1NT as a forcing bid. If you do, then you can respond with that bid followed by a jump in partner's major. This shows a limit raise, but only three card support.
What About a Hand With More Than a Limit Raise?
One of the great features of the Forcing Club system is knowing that when partner opens, her hand is limited to 15 points. That means you can jump to game without worrying about missing slam when you also have an opening hand. You don't have to wait for that "weak freak" hand which has five-card support for partner's major.
But sometimes you have a wonderful hand in support of partner's opening bid and you want to look for a slam. It's nice to be able to ask for aces at a low level, so you can use Baby Blackwood if that's the informaton you need.
You can also use a convention called Jacoby Two Notrump. After partner opens with a major, a jump to 2NT implies an opening hand with four-card support.
Rebids by Opener