The foundation of the L-System is to open a Major suit with as few as 8 to 12 high card points, and to open a Minor suit with as few as 10 to 12 high card points on the one level. Any opening bids on the two level are considered preemptive in nature.

Below is a summary of the L-System with the corresponding responses.

Club Opening

• Non-forcing, 4-10 high card points.
• Non-forcing, 7-10 high card points, 5-card Heart suit.
• Non-forcing, 7-10 high card points, 5-card Spade suit.
• Game-forcing, 11 high card points plus, but imparts no information about distribution.
• Non-forcing, 7-10 high card points, shows either a 6-card plus suit, or a 5-card suit with a 4-card Major suit.
• Non-forcing, 7-10 high card points, shows either a 6-card plus suit, or a 5-card suit with a 4-card Major suit.
• Weak Jump Shift, not game-forcing.

Diamond Opening

• Opener Meaning Responder Meaning
• 7 or fewer high card points, Negative Response.
• high card points plus, natural and game-forcing.
• 4 or fewer high card points, Weak Jump, long Spade suit.
• 4 or fewer high card points, Weak Jump, long Club suit.
• 4 or fewer high card points, Weak Jump, long Diamond suit.
• 4 or fewer high card points, Weak Jump, long Heart suit.

The concept behind the L-System is to pass all hands with even distribution and fewer than 13 high card points. If the point count is 13 to 15 high card points, then the hand should be opened with 1 Club, also with evenly distributional holdings.

If the distribution is slightly off and the point count is between 16 and 18 high card points, the preference is to bid 1 Diamond, but if the distribution is balanced, the preference is to open 1 No Trump.

All hands containing 19 to 20 high card points, regardless of shape, should be opened with 1 Diamond. All holdings with 21 to 22 high card points and even distribution should be opened with 2 No Trump.

Heart Opening

• 5-card Heart suit plus, not suitable for preemptive openings.
• 11 plus high card points, natural and forcing for one round.
• 10-12 high card points, evenly distributional holding.
• 11 plus high card points, natural and forcing for one round.
• A single raise shows 10-12 support points.
• A double raise shows fewer than 10 points and is weak.
• 16 plus high card points, good Heart support.
• A jump is weak and preemptive, long Spade suit.
• A jump is weak and preemptive, long Club suit.
• A jump is weak and preemptive, long Diamond suit.

Spade Opening

• 5-card Spade suit plus, not suitable for preemptive openings.
• 10-12 high card points, evenly distributional holding.
• 11 plus high card points, natural and forcing for one round.
• A single raise shows 10-12 support points.
• A double raise shows fewer than 10 points and is weak.
• 16 plus high card points, good Heart support.
• A jump is weak and preemptive, long Club suit.
• A jump is weak and preemptive, long Diamond suit.
• A jump is weak and preemptive, long Heart suit.

No Trump Opening

• 10-12 hcps May be an unbalanced holding with a 5+card Minor suit.
  A holding with values not suitable for preemptive bids.
• 11 or fewer high card points.
• 11 or fewer high card points, no game interest, requests partner to pass or bid 2 .
• 10 plus high card points, forcing for one round.
• 10-13 high card points, natural bid.
• 13-14 high card points, balanced distribution, invitation to 3 NT.

Rebids by Opener After 2 Diamonds

• 10-12 hcps May be an unbalanced holding with a 5+card Minor suit.
• A holding with values not suitable for preemptive bids.
• 10 plus high card points, forcing for one round.
• Natural rebid showing a 4-card Heart suit.
• Natural rebid showing a 4-card Spade suit.
• Shows a minimum hand without a 4-card Major suit.

Opening Bids on the Two Level

• Preemptive bid, 6-11 high card points, 5+suit. Responses are Standard American.

No Trump Opening

• 21-22 high card points, even distribution. Responses are Standard American.

Preemptive Bids on the Three Level

• Preemptive bid, 6-11 high card points, 7+suit. Responses are Standard American.

Mr. Hong Liu suggests that using his L-System allows the bridge player to open a 5-card suit with as little as 8-12 high card points either at the one or two level.

This suggestion is based on the tradition that an overcall can be made on such few values, and therefore why should it not be possible to open with such few values. Another advantage is perhaps the lack of artificial conventions, treatments, and methods.

The 1 No Trump openings for a Minor suit require only 10 to 12 high card points as opposed to 8 to 12 high card points. The narrower range allows the partnership to more accurately judge the situation on the two level.

This allows the partnership to bid preemptively with a holding of only 8 or 9 high card points and a 5-card suit, either a Major or Minor suit.