[Periiz]

--- WARNING: Here comes a wall of text ---

Ok so I've been playing for quite some time that a 2♣ response over 1M could be short, ensuring 5+ diamonds for the 1M - 2♦ sequence, and that seems alright. Also, we've included 3 card limit raises on the 2♣ and used a 2♦ by opener now as a not strong hand (but not denying game over limit) and everything else pretty natural with good hand (like 15/16+). Apart from the 2♦ negative (this is quite nice) I never really thought it was a good set of bids for the opener, specially if you have to jump to level 3 with minors, but the responder's bids have also made me sick. After a simple auction:
1♠ - 2♣
2♦ - ?

2♠ now shows the limit 3 card raise and is passable. That means that responder had to bid 3♠ to show a FG hand with spade support, could be as short as 2 clubs but it also could have a good long suit. Of course, since the 2♦ is negative, this is less of an issue, but a hand that did not want to simply bid game is at least mild slam invitational (or maybe it thinks that 3N could be best?), so distributional trick taking potential is even more important since we're talking about a possibly "low count slam". But if the opener showed a positive hand...
1♠ - 2♣
2N (positive balancedish as we play now)
Responder could still have 3 different hand types and opener is quite unlimited. Having to bid 3♠ after responder showed a positive with either AKxxx or Qx of clubs cannot be a good thing.
Since our goal was to make 1M - 2♦ show diamonds, I think we should have a way to show clubs as well.

Because of that, I started thinking of a better overall structure and after looking the internet for some ideias (basically bridgewinner's comment section) I found this:
1M - 2♣, now what?
2♦ negative
2♥ positive but without 4 of the other major nor 6+M (so it is either balanced or 5M 4m hands)
2♠ positive with 4 of the other major
2NT positive with 6+M (wrong siding issues?*)
3 level for special 5-5 positive hands or some crazy distributions

That seems quite nice. Opener shows if he is minimum or not. If positive, he shows his major suit holdings, or some freakish shape, otherwise bids the nebulous 2♥ in response of the nebulous 2♣.
This also reminds me of the (I believe it was?) carrot responses to strong 1♣, where there would be a "positive but not really interesting hand" bid, usually 1♥ or 1♠ (Magic Diamond also has it, of course), showing no 5M, no 5-5, no 6m. This seems like a good principle, not showing side minors unless asked or really distributional.

*Maybe 6+M hands could also hide in the catch-all 2♥ and 2N be only with stoppers? Or maybe with 6+ really good cards, probably a shortage, meaning something like "I'd rather not play no trumps... Really". I never felt happy bidding 2NT with 6+M, and I'm still not, but I will be considering that this is the system for now.

I would think that after the 2♥ bid, responder clarify. My main concern here is differentiate club hands and balanced hands, with or without support, and thus I am asking for ideas. Bidding 3♣ to show clubs seems bad since I cannot raise under 3NT, but I could live with that (could I really?). Opener denied 4 of the other major, so this should help. The first idea was something like:
1M - 2♣
2♥ - ?
2♠ single suited clubs (could it be 5332? 5C-3M-32?)
2N bal (could have 3 card supp?)
3M support with 5+ clubs (could it be 5332?)
3N is kinda weird, we could dump the 3 card limit raise here so opener doesn't get too excited with his strong hand (better than bidding 4M, since opener could be really strong).
Other 3 level bids could be naturalish? Showing the other major would imply 5, since opener denied 4? I think these are ok (not perfect, but ok)
3 level bids in a transfering fashion, showing clubs and next, is also interesting.

The other part of the structure, the negative opener:
1M - 2♣
2♦ - ?
2M has to be passable, showing the 3 card limit raise. The whole ideia was being able to play at the level 2 and not 3
2oM could show a balanced hand, and everything else would show clubs. I liked this, I think it has the "rightsiding notrump" in mind and only biding it with some stoppers. But I also see that "if we don't tell them what to lead, they won't know that 3NT can fail", so I wouldn't mind having the balanced hand bid 2N and the club hand bid the other major. Might even be easier for the memory, right?
3M FG with support? The thing is... Could it be balanced? Should it show clubs and support? Since opener is limited, is it that important to show the side suit now?

Ok, these things all seems nice, and I started a teaching table at BBO with my very self on each seat and started bidding (I have this habit of spending quite some time bidding with myself after theorizing some bidding conventions and ideias). I made some code to generate 1M openers only and 2♣ responses only (mostly), which is nice. At first I was using the 2oM showing "balanced could have support aproach" and the main problem arised when the responder had 4 of the other major after the 2♦ negative. I mean, we could very well be playing on the 4-4 fit major game as everyone else is. Bidding could get quite cramped like
1♠ - 2♣
2♦ - 2♥ to show balanced
What is opener supposed to do? Bid 2♠ whenever he has 4oM? (This looks ok) 2N with stoppers? And with 6 Cards he bids 3♠ since fit is guaranteed? Maybe responder was interested in hearing about any 4 card minor opener might have with a super strong balanced hand? Ok, we could use some switch or artificiality at the 3 level after responder showed a balanced hand. What about a Lissabon approach? 3♣ = 4 hearts, 3♦ = 6 spades, 3♥ = 4 clubs, 3♠ = 4 diamonds, this would also maybe show too much for a responder that only wanted to give a choice of games.
There's also the "leave 2oM to clubs and 2N for balanced" thing, which doesn't change these problems much. I think that even with 5-3 major fit it is VERY important to be able to suggest 3N, so I wouldn't like the bidding to go 2♥/N-3N without ever telling opener we had fit.

Or maybe the issue is that I'm just asking too much, and having the 3 card limit raise together with everything is costing me some space after the 2♦ negative? What are your ideias for the nebulous 2♣? I liked the also nebulous but actually quite descriptive positive 2♥ bid.

So much 2♥ and 2♠ artificial bids may cause some memory issues, but that's on me
Also, leaving some random artificial 2♠ to be doubled all over the place when we have hearts could be annoying, but I don't really care that much.

This article has some neat ideas but it wouldn't work with the limit raise option merged into 2♣. Playing on 2M is a really nice thing from time to time.

[dokoko]

What about 1M-2♣-2M as negative and 1M-2♣-2♦ as catch-all?

This is obviously better when M=♥. Responder has the same rebids over 2♥ negative as he had over 2♦ negative (2♥ being replaced by pass) and has an additional (forcing) 2♥ rebid over the catch-all rebid.

It's probably also better when M=♠. Responder loses one rebid over the negative rebid and wins two over the catch-all rebid.

[nullve]

Instead of

1M-2♣; 2♦ = negative

or

1M-2♣; 2M = negative,

which are the two standard variants, I kind of play

1♥-2♣; 2♥ = negative (and passable)

and

1♠-2♣; 2♦ = negative (then 2♠ = LR),

which allows

1M-2♣; 2♦-2♥ = GF relay.

[DavidKok]

I play something very similar, but my nebulous 2♣ never contains a limit raise with 3-card M (those go via 2NT). To be precise, I bid 2♣ with one of

• GF with clubs
  
• GF with a fit and no own 5-card suit to mention
  
• 11-13 balanced 'invitational' without a fit (opener sometimes opens on 9-10 HCP, what can you do)
  
• Invitational (10-11 HCP) with a 5-card ♥ (over 1♠ only)

This way a sequence like 1♠-2♣*-2♦*-2♠ is 100% GF (the invitational hands rebid 2NT and 2♥ respectively). Also we would jump to 4♣ on the second round holding support for the M and a decent (AKTxx just about makes the cut) club suit, so other ways to support partner deny length in clubs.

I don't have experience with the structure denying the other major or showing extra length first by opener, we just play (after 1♠-2♣*):
2♦ - any minimum
2♥ - 4+ hearts, can be a minimum(!)
2♠ - some extra values, 6+ spades
2NT - 15+ balanced, GF
3♣ - natural, GF
3♦ - natural, GF

[Periiz]

I think that using 2M as the negative is ok, but it would have to be a true negative. We bid 2♦ negative with fairly strong hands and the positive are a good start for slams, actually. I mean, I couldn't bid the 2M with a 14 count, probably (is this really an issue?).
Well, it's true that it's definitely better for hearts, maybe using a different system for heart or spade opener makes sense here.

[nullve]

 Periiz, on 2020-July-05, 19:29, said:

I think that using 2M as the negative is ok, but it would have to be a true negative.

Agree. So I actually divide my 1M range ("10-21") into four equally big subranges O1 ("10-12"), O2 ("13-15"), O3 ("16-18") and O4 ("19-21") and play

1♥("10-21, 5+ H, unBAL")-2♣; ?:

2♦ = O2 (all shapes) OR O4, some shapes OR (rarely) O1, afraid of getting passed in 2♥ after 1♥-2♣; 2♥
...2♥ = relay (GF)
......2♠ = not O2
.........2N = relay
............3♣ = O1 (I don't have any system over this)
............3♦+ = O4, S(♥)|2N-3♣; 3♦+
......2N+ = O2, S(♥)
...(...)
...I'm also considering
...2N = weak relay (less revealing opposite O2)
......3♣ = O2
......3♦+ = O4, S(♥)|2N-3♣; 3♦+
2♥ = O1 (passable with a LR, so maybe not all shapes)
...P = the LR
...2♠ = GF relay
......2N+ = S(♥)
...(...)
2♠ = O4, most shapes
...2N = relay
......3♣+ = S(♥)|3♣+
...(...)
2N+ = O3, S(♥)

and

1♠("10-21, 5+ S, unBAL")-2♣; ?:

2♦ = O1 (all shapes) OR O4, some shapes
...2♥ = GF relay
......2♠ = O4
.........2N = relay
............3♣: not used at the moment (although I have some ideas)
............3♦+ = O4, S(♠)|2N-3♣; 3♦+
......2N+ = O1, S(♠)
...2♠ = the LR
...(...)
...I'm also considering
...2N = weak relay (less revealing opposite O1)
......3♣ = O1
......3♦+ = O4, S(♠)|2N-3♣; 3♦+
2♥ = O2 (all shapes)
...2♠ = relay (GF)
......2N+ = S(♠)
...(...)
2♠ = O4, most shapes
...2N = relay
......3♣+ = S(♠)|3♣+
...(...)
2N+ = O3, S(♠),

where the (relay) structure S(M) is built around

2N = "4+ OM or 1-suited"
...3♣ = relay
......3♦ = "1-suited"
......3♥+ = "4+ OM"
...(...)
3♣ = "4+ D"
3♦ = "any 5-5"
3♥+ = "4+ C"

and S(M)|3♣+ and S(M)|2N-3♣; 3♦+ are the restrictions of S(M) to the red and blue parts, respectively.

[fromageGB]

If the problem is that the 2♣ bidder could have a range of hands, then why try to take space describing opener's? If opener always relays with 2♦ (well, OK maybe expect for a few closely defined hands) then let responder describe his hand. Probably everything other than 2M is GF, and there are plenty of bids to describe the hand and keep the bidding low.

[nullve]

 fromageGB, on 2020-July-06, 08:03, said:

If the problem is that the 2♣ bidder could have a range of hands, then why try to take space describing opener's?

Because

1) At least as much is known about Opener's strength and shape as about Responder's.
2) There is (much) more space after 1M-2♣ (2♣ viewed as a relay) than after 1M-2♣; 2♦ (2♦ viewed as a relay).

[dokoko]

 nullve, on 2020-July-05, 04:28, said:

I kind of play

1♥-2♣; 2♥ = negative (and passable)

and

1♠-2♣; 2♦ = negative (then 2♠ = LR),

which allows

1M-2♣; 2♦-2♥ = GF relay.

Interesting idea!

[arijit079]

I am also trying to design such a system. However, my question is how can you find a 4-4 fit in the other major if the opener has a minimum hand and the responder has a potential slammish hand with 4 card in other major and 5♣.

e.g.
1♠ 2♣
2♦ 2♥ (assuming it shows a balanced GF raise in ♠)

what if the responder has 5 ♣ and 4 ♥ GF and the opener has 5♠ and 4 ♥ and minimum?

Similarly for

1♥ 2♣ how can we find a 4-4 ♠ fit with responder having 5 ♣+4 ♠ and the opener having 4♠+5♥ minimum?