[pilun]

Alerting and Announcing regulations vary.

In Australia, we are required to announce length for 1♣ and strength for 1NT. No "Could be short" announcement for a Precision 1♦.

In 3rd & 4th seats we play "modern" Precision, where 1♦ = 2+.

In 1st & 2nd seats we play a Moscito variant. In our case, 1♥ = hearts, 1♠ = majors, 1♦ = 4+ SPADES.
We pre-alert with "Strong club. 1♦ opening = spades in 1st & 2nd seats."

Despite that, when we "Alert" partner's 3rd seat 1♦ opening, many opponents think "Aha! Spades!" and proceed accordingly.

Do we have a special duty of care here? What should we do and say?

[Stephen Tu]

Maybe I'd tweak your pre-alert of 1d to be "4+ spades in 1st & 2nd, diamonds or 2+ balanced 11-13 (or whatever range applies for you) in 3rd/4th"

If the opps still get it wrong with that, and your CC clearly marked as varying systems, then it's on them.

[pescetom]

It's not a set of agreements you can clearly explain in a few words and not easy to deduce from a system card (for some, that might be another reason to play it).

A nige1 sheet of unusual stuff with boxes for 1-2 and 3-4 positions containing explanations of each 1 level opening seems the obvious solution. You can hand it over during pre-alert and point to an explanation on it if requested after an alert.

[mycroft]

(agreeing with Stephen Tu, but different)

If you tell me that 1♦ is spades 1 and 2, and don't say anything about 3 and 4, I will assume it's natural.

If then I'm alerted to 1♦, then obviously it's spades, and you're in first or second seat. Even if my LHO has already passed.

This is basically what you're saying, but I'm pointing out where I think it's coming from.

You play an alertable 1♦ in all seats; whether or not a pre-Alert is required for Precision style 1♦, since you're pre-Alerting anyway, just add that. Then the "oh, right, spades" trigger won't be quite so automatic.

And yes, "could be 2" would solve your problem here (but I bet some of my favourite ACBLers would take advantage of the wording to say "it's NF, so we Announce" and decide to use "could be zero" rather than, you know, "Spades" for the first two seats. I bet for some of them, some of their "surprise" when the director finally got called would even be honest). But you don't have that.

I guess what I am saying is that the opponents are entitled to your agreements, and it's at least partially your responsibility to ensure they're not confused. And, when your system falls down a hole in your RA's regulation, yes, I do think you have a special duty of care. But I think you should try very hard not to violate those regulations (as opposed to going beyond what is required - is the difference clear?) in your "care". Hence my suggestion that you make clear at the outset that 1♦ is always Alertable, but has two very different (Alertable) meanings depending on seat.