After opener's "classic" reverse (which we play is 17+), responder has a few options:
- If the 4th suit is available on the 2-level, it shows a generic minimum
- 2NT is always a minimum; if the 4th suit is available, it is natural with 6-7 - if not, it's a generic minimum
- Responder rebidding his suit is game-forcing with 5+ cards
- Raising either of opener's suits is game forcing
If opener gets a minimum 4th suit response, he can bid 2NT or 3 of his first suit with a hand that wants to sign off. If so, responder can correct to either of opener's suits or rebid his own to play. If opener gets a natural 2NT response, he can pass or rebid 3 of his first suit with a minimum. If opener gets a generic 2NT response, he can pass (which might not be the best idea) or he can bid 3 of his first suit with a minimum. All other sequences create a game force.
So a sequence would look like:
1♣ - 1♠
2♦ (17+)
..............2♥ (generic minimum)
..............2♠ (game forcing, 5+ spades)
..............2NT (natural, 6-7, non-forcing)
..............3♣ (3+ clubs, game forcing)
..............3♦ (4+ diamonds, game forcing)
..............3♥ (splinter for diamonds)
..............3♠ (good 6+ spades, slam interest)
..............3NT (natural, 8-10 or so)
..............4♣/♦ (natural, 5+ support, slam interest)
Any feedback would be appreciated, thanks.