[gwnn]

3NT=6 hearts+5 cards in a minor, ~7-10 hcp is a great use, as far as I know coming from awm, and my favourite choice.
Fred (said he) likes 3NT=6-5 in the majors or better, just under opening strength.
I saw on some CC's (I think Ekeblad among others) 3NT=both minors, weak.

Finally for something quite crazy (but which just might work) that I read long ago on the forums from dellache: 3NT=a good 6-card minor, near-minimum opening. There was some special point-counting method that defined the bid better, I believe.

aha, found it (my memory failed me, the hands are not near minimum): http://www.bridgebas...27-3nt-opening/

finally, it is quite probably unsound to play it as "to play", but at least there was a semi-flame war on whether it is legal.
http://www.bridgebas...3nt-as-to-play/

[aguahombre]

helene_t, on 2012-August-30, 04:52, said:

It is generally best to say what a bid shows, rather than what it asks partner to do.... in this case, it is easy to explain what the 3nt bid shows: a weak hand with a long minor.

I have been pounding on this on other threads ---just how wrong it is to explain a bid in terms of what you are going to do next.

But, with Jilly's explanation of how they play the 3NT opening which shows a long minor I believe this might be the exception I could not find previously. There are many reasonable things responder can do after this 3NT opening:

Pass
Bid 4M to play
Bid 4C for pass/correct
Bid 4D for pass/correct with a hand too good to play in only 4C.
Bid at the five level pass/correct with an appropriate hand.
Bid 4N as an agreed tool.

And so on. Perhaps anyone who really has (only) 4C as their bid over 3NT should be disclosing it, since it is so entirely unexpected and unworkable.

[MickyB]

jallerton, on 2012-August-29, 13:27, said:

So what meaning do you consider to have the best theoretical merit (in the context of a natural system)?

No idea. I was just fairly confident that 3N = good 4H bid is reasonable, simple, but not the best theoretical meaning

Thinking about it, the disadvantage of 3N [or 4m] promising a specific suit is that it's much easier to defend against, in direct seat at least. It's unclear what a dbl of 3N [good 4M bid] should show.

3N showing a two-suiter is surprisingly rare, I'd expect 3N = minors to be quite a common agreement. IIRC Brad+Fred play it as the majors. I don't really get that, hearts+minor makes more sense to me, or perhaps something multi-ish like majors or minors.

Edit: Don't know how I missed Gwnn's post. 3NT = H+minor was the "MickyB 3NT" for about 5 minutes.

Reedit: It's ok, the MickyB 3NT can show 5H6m instead of 6H5m.

This post has been edited by MickyB: 2012-September-02, 20:24

[Zelandakh]

This is a theme that seems to come up on these forums regularly enough. A couple of options from the last thread that have not yet been mentioned are a specific ace ask and a good preempt to 4m (with 4m natural and weaker). The former is a rare beast but great when it comes up; the latter is an attempt to split minor suit preempts up more evenly between 3m, 3NT and 4m and avoids the temptation to open 3m on some hands that are worth 4 on playing strength but would prefer to keep 3NT in the picture. Of all the possibilities, the solid strong major preempt is surely the one gaining most popularity in expert circles in recent years.

[han]

I have never heard of anybody play it as a solid major.

[phil_20686]

han, on 2012-September-06, 03:35, said:

I have never heard of anybody play it as a solid major.

For a while our system notes had it as the equivalent of 8 solid. E.g. AK to eight and an ace, or KQJ to 8 and an ace. Not quite so restrictive, but not so far away.

Then we moved to more flexible definitions based on what we thought a 4M opener looked like depending on seat and vul.

[Zelandakh]

han, on 2012-September-06, 03:35, said:

I have never heard of anybody play it as a solid major.

I typed the wrong thing and have edited the post to reflect what I meant to write. A 3NT opening as a solid major is also a possibility though and I am reasonably sure that at least some experts play it. As I recall, one of the benefits of the method is incredible accuracy in slam auctions (down to side jacks) at the cost of frequency (in comparison with the strong 4M opening option).

To add another possibility which does not look to have been mentioned: Magnusson - Ingimarsson are playing their 3NT opening as 6+m, 5+M (in addition to including this hand type in their 2♠ opening and including some 6+♦, 5+M hands in their 3♣ opening).