1 | 12+ HCP, 3+ (Includes 3 3 but not 4 4) |
1 | 12+ HCP, 4+ or 4 4 3 2 |
1 | 12+ HCP, 5+ |
1 | 12+ HCP, 5+ |
1NT | 15 - 17 balanced |
2 | GF or 23+ balanced |
2 | Weak Two in |
2 | Weak Two in |
2 | Weak Two in |
2NT | 20 - 22 balanced |
In this system there are countless varieties. The most variable are the responses to the opening bids 1 and 1. A 2 over 1 may or may not be game forcing, 2NT can be natural, or it might show some kind of raise, a jump shift is either weak or strong, etc.
Some variants are: