[1eyedjack]

The Tournament Rules posted on ACBL tourneys advise that methods must comply with the General Conventions Chart. And for those of us who don't know what that means they provide a convenient hyperlink which takes you to here:

http://www.bridgebas...blgeneralcc.pdf

Selectively extracting two sections of this we find that:

Quote

Unless specifically allowed, methods are disallowed

Followed by

Quote

3. TWO CLUBS ARTIFICIAL OPENING BID indicating one of:
a) a strong hand.
b) a three-suiter with a minimum of 10 HCP.
4. STRENGTH SHOWING OPENING AT THE TWO LEVEL OR
HIGHER that asks for aces, kings, queens, singletons, voids or trump
quality and responses thereto.
5. TWO DIAMOND ARTIFICIAL OPENING BID indicating one of:
a) both majors with a minimum of 10 HCP.
b) a strong hand.
c) a three-suiter with a minimum of 10 HCP.
6. OPENING BID AT THE TWO LEVEL OR HIGHER indicating two
known suits, a minimum of 10 HCP and at least 5–4 distribution in the
suits.

This is the only section that refers to 2-level openings.
A natural weak 2 in a major does not fall in any of the expressly allowed categories, nor indeed does a natural strong 2 (unless it also promises a second specified suit or requires control-showing responses). Not being expressly allowed, one presumes that these are disallowed (per first quote above).

Am I to understand that just about every player in an ACBL event on BBO is in breach?

[blackshoe]

No. In general natural bids are not regulated (there are some exceptions). Yes, I know the GCC doesn't explicitly say that. It's still true.

[mgoetze]

blackshoe, on Oct 3 2010, 05:52 PM, said:

No. In general natural bids are not regulated (there are some exceptions). Yes, I know the GCC doesn't explicitly say that. It's still true.

The question is, of course, how one is to know that natural 1NT openings showing 9-11 points are regulated while natural 2♥ openings showing 9-11 points are not...

[1eyedjack]

Thanks for that. I have had another look and I see what you mean. It starts off by defining what bids are natural, and presumably by implication anthing that follows regulates that which is not natural.

So it seems that non-vul v Vul I might (if I felt so foolhardy) by agreement decide that a "fertiliser" 2H opener that shows 4+ hearts and 0-6 points is GCC legit. Hmmm

[hrothgar]

mgoetze, on Oct 3 2010, 07:57 PM, said:

blackshoe, on Oct 3 2010, 05:52 PM, said:

No. In general natural bids are not regulated (there are some exceptions). Yes, I know the GCC doesn't explicitly say that. It's still true.

The question is, of course, how one is to know that natural 1NT openings showing 9-11 points are regulated while natural 2♥ openings showing 9-11 points are not...

No.
The only thing that matters is what the particular set of administrators that you are dealing with happen to believe is legal...

Regretfully, since the ACBL doesn't actually publish consistent explanations regard what is legal, said administrator could believe virtually anything

[rwbarton]

mgoetze, on Oct 3 2010, 12:57 PM, said:

blackshoe, on Oct 3 2010, 05:52 PM, said:

No. In general natural bids are not regulated (there are some exceptions). Yes, I know the GCC doesn't explicitly say that. It's still true.

The question is, of course, how one is to know that natural 1NT openings showing 9-11 points are regulated while natural 2♥ openings showing 9-11 points are not...

By reading item 9 under RESPONSES AND REBIDS:

ACBL GCC said:

Allowed:
...
9. ALL CALLS AFTER A NATURAL NOTRUMP opening bid or direct overcall, EXCEPT for natural notrump opening bids or overcalls with a lower limit of fewer than 10 HCP or with a range of greater than 5 HCP (including those that have two non-consecutive ranges).  See #7 under DISALLOWED.

As you can see, a 9-11 natural 1NT is not disallowed but conventional responses are (natural responses being allowed by default; #7 under DISALLOWED makes this clear). This is the ACBL's way of dissuading you from playing a 9-11 1NT, but you might want to play it anyway in 3rd when NV (or 9-14 in a light opening system, or "0-5 or 11-14", or whatever floats your boat). You can't use your fancy artificial runout system if you get doubled, though.

1eyedjack, on Oct 3 2010, 01:05 PM, said:

So it seems that non-vul v Vul I might (if I felt so foolhardy) by agreement decide that a "fertiliser" 2H opener that shows 4+ hearts and 0-6 points is GCC legit. Hmmm

It is, but the same applies as after a 9-11 1NT: no conventional responses. See #6 under RESPONSES AND REBIDS.

Also, hrothgar is quite right that the local director may well decide your 0-6 HCP, 4+ hearts 2♥ bid sounds illegal and disallow it.