Bergen's Jacoby 2NT

Auctions will be explained in terms of 1S-2NT. 1H-2NT is similar.
Opener's rebids:
3C = Non-minimums with singletons OR big balanced or semi- balanced hands.
3D = Non-minimum two-suiters OR *any* good hand that is anxious to learn more about responder's distribution.
3H = All hands with voids.
3S = All minimums with singletons.
3NT = Good hands with a 6-card suit.
4m = Decent minimums, identifying cheaper ace or king.
4H = Decent minimums with no control in a minor suit.
4S = Signoff.

"Decent" tends to center around 13 HCP. 5-4 qualifies as a 2-suiter when there are 13 HCP. Big balanced is 17+, big semibalanced is 15+.

Over 3C or 3H opener will usually relay; over 3S, sometimes. The relay suit is the next higher. Opener shows his shortness in steps, in the order C, D, OM. Over 3C-3D, with the big balanced or semi- balanced hand opener bids the cheaper minor-suit control. Non-relay bids are asking bids, again in steps. That is, over 3C, 3H is an asking bid in clubs. Responses are in steps, showing control of the suit asked: 1st step shows no control, 2nd shows Q or XX, 3rd shows K or X, 4th shows ace.

Over 3D responder shows shortness: 3H = doubleton club, 3S = doubleton diamond, 3NT = doubleton heart, 4C = non-minimum 4x3, 4D and 4H show singleton club and diamond respectively and a hand too strong to splinter, and 4S shows a minimum 4x3. (Bergen's splinters are limited to 12 HCP at most.)

After all of this, cuebids and kickback follow.

Source: Don Varvel (