[barmar]

I was playing in a BBO ACBL tourney last night. In 4th seat I opened 1♣, and LHO overcalled 1NT with no alert. Most people I've encountered in the US play that a 1NT overcall by a passed hand is unusual -- since they can't have a strong NT, they don't have to jump to 2NT to show that kind of hand. For protection, I asked for an explanation, and he explained "balanced 10-11".

After the hand, I suggested to him that he should have alerted. He didn't think so, since his bid was natural, and the weakness was obvious since he didn't open.

The only related items in the ACBL Alert Procedures are:

Quote

Natural 1NT overcalls in the range of 14 to 19 HCP require neither an Alert nor an Announcement. If the top or bottom limit of the natural notrump overcall is out of that range or conventional by an unpassed hand, an Alert is required.

That talks about overcalls by unpassed hands, not by passed hands.

Quote

Non-jump unusual notrump bids below 4NT, except those made by a passed hand, must be Alerted.

This means that the meaning I expected doesn't have to be alerted. It doesn't say what DOES have to be alerted.

The ACBL Alert Chart also says that NT overcalls with less than 14 HCP have to be alerted, without the caveat about unpassed hands, but that could just be for brevity in the chart.

We weren't damaged because I found out the meaning, I'm just asking whether this is alertable on general principles.

[blackshoe]

Seems to me it makes sense that it wouldn't be alertable. OTOH, ACBL alerting regs aren't required to make sense, and often don't.

[aguahombre]

A very good question.

One thing I am sure of is that anyone who uses a 1NT overcall by a passed hand opposite a passed partner as 10-11 balanced would not know the answer either and would not know to alert it, if appropriate. He undoubtedly has never looked at the scoring charts for doubled contracts, let alone the Alert Chart.

[barmar]

Yeah, I didn't really want to comment on the advisability of this treatment, but I agree with you.

The player was from the Netherlands, anyone know what the usual meaning of this bid is over there?

[bluejak]

Oh, that's easy. Having played at Alkmaar earlier this year, 1NT means: "It is my turn to bid, I have passed once, and I have 13 cards so I cannot pass again."