[Xiaolongnu]

Where is the law reference or system policy or protocol that says that playing precision, a super short diamond opening is allowed?

Explicitly, 1♣ any 16+, identifying the system as precisionoid.

1♦ promises light to minimum opening hand, to be exact, an average hand to less than two kings above average strength, any distribution that has no 5 card M or the appropriate 1NT.

The original problem is someone is playing a Stayman opening where the 1♣ opening is stayman, 1d no 4M. I reduced the minor openings to subdivisions of the precisionoid weak minor, in an effort to prove that the system is not hum. The challenge I received was that the stayman opening promises either length in one or the other major suit.

So how do I prove that the precision diamond is not hum system?

[chasetb]

I don't know about Singapore, but I know for the ACBL that it states directly in the 2012 Convention Chart :
OPENING BIDS
1. ONE CLUB OR ONE DIAMOND may be used as an all-purpose opening bid (artificial or natural) promising a minimum of 10 high-card points.

http://www.acbl.org/...ntion-Chart.pdf

Also, directly on the World Bridge Federation's website, there is nothing wrong with a 1♦ opening that could be as short as 0, because it DOES NOT DEFINE LENGTH IN ANY PARTICULAR SUIT. Going on to 1♣ and 1♦ as showing and denying 4M respectively, it looks to me to be HUM according to the link below, but it's something that I'm sure would be allowed because it doesn't look destructive (of course, if you open 1♦ on a 2227, I'd be pissed).

http://worldbridge.o...tems/policy.asp

[Cyberyeti]

Very jurisdiction dependent, EBU

Orange book 12 C 4 1♦ openings - basic
A 1♦ opening may be played to have any meaning, forcing or not, as long as this does
not include unbalanced hands with 5+ Hearts or 5+ Spades (unless there is a minor
suit of equal length or longer).

This is subject to the general rules that govern minimum agreed strength for an opening bid.

Strong diamond is covered separately and also permitted.

[campboy]

It is not a HUM because the HUM definition specifically says that one of a minor in a strong club or strong diamond system is excluded.

[RMB1]

 Xiaolongnu, on 2012-August-20, 00:16, said:

The original problem is someone is playing a Stayman opening where the 1♣ opening is stayman, 1d no 4M. I reduced the minor openings to subdivisions of the precisionoid weak minor, in an effort to prove that the system is not hum. The challenge I received was that the stayman opening promises either length in one or the other major suit.

If 1C = opening values 4cM and 1D is like 1D in a strong 1C system, then this is not a strong minor system and both 1C and 1D are HUM because 1C shows length in H or length in S and 1D shows length in C or length in D.

[Cyberyeti]

 RMB1, on 2012-August-20, 16:07, said:

If 1C = opening values 4cM and 1D is like 1D in a strong 1C system, then
this is not a strong minor system and both 1C and 1D are HUM because
1C shows length in H or length in S and 1D shows length in C or length in D.

Aren't there non HUM systems that play 1♣ with one of the meanings of a weak no trump with a 4 card major (because 1♣-1♦(neg)-1M is a weak no trump with 4 of the major and 1♣-1♦-1N is a strong no trump).

Also (certainly in the EBU, not sure about other jurisdictions) it was always legal to play both 1♣ and 1♦ as clubs/diamonds/balanced (ie basically a strong club's 1♦ and a strong diamond's 1♣), we did so with a big forcing (and always unbalanced) 1N.

I don't see any issue with the diamond, but the club might be suspect.

[campboy]

 RMB1, on 2012-August-20, 16:07, said:

If 1C = opening values 4cM and 1D is like 1D in a strong 1C system, then this is not a strong minor system and both 1C and 1D are HUM because 1C shows length in H or length in S and 1D shows length in C or length in D.

Yes, I didn't read the OP carefully enough. The 1♦ opening is HUM unless played in conjunction with a strong club (which I thought it was being).

[bluejak]

Let me summarise.

What you are permitted to play is only a matter of Law insofar as Law 40B2A delegates it to the RA, who normally delegates it to the TO using Law 80A3 who uses Law 80B2 to regulate it.

Regulations are different in different jurisdictions which is why you are getting a few answers which are correct but different from each other.

By talking about HUMs you suggest that you are in a jurisdiction that uses WBF or EBL system regulations.

Under WBF regulations you may play a strong 1♣ with a loose diamond and that is not a HUM.

However, you then ask about a pair who do not want to play a strong 1♣ but seem to be playing 1♣ and 1♦ as fairly loose, perhaps following the English MidMac system, where 1♣ is any opening bid with a four-card major but no five-card major, and 1♦ is any opening bid with no major of longer than three cards. It seems possible that that is a HUM system, though legal in English club bridge [Level 3].

[blackshoe]

He's in Singapore.