[pstansbu]

I tend to alternate strong and weak NT with different partners. In a moment of aberration I opened 1NT on a 15 count when playing with a weak convention card. No sooner had I placed the card on the table did I realise my error (I know that might be immaterial - I had already pulled the card with apparent intent) On the night I let it stand just in case. Could this ever be classified as unintended (assuming I made a timely change)?

[blackshoe]

At the time you made your bid, you intended to bid 1NT, so no, this is not a 25A "unintended call" situation.

[barmar]

In ACBL, if you'd realized your error a fraction of a second earlier, I think you could have retracted it. Our rule is that the bid isn't made until it's placed on or near the table with intent, so you can correct it if you discover your error while it's on the way to the table (although there may be UI issues).

But I think EBU's criteria is when the bid is taken out of the box with apparent intent (as you quote). In this case, it wasn't just apparent intent, it was actual intent. You didn't realize your error until well after the deadline, so it's too late.

[weejonnie]

I would agree - your intent (when the cards were removed from the box) was to open 1NT. The problem arises when your partner announces "12 - 14". It will be very difficult to persuade a director that you realised your mistake between putting the card on the table and partner's announcement. Suppose partner (having announced 12 - 14) makes a quantitative 2NT raise. You have an obvious (and ethical) 3NT call if you realised that you had opened 12-14 with 15 points before the announcement - and an equally obvious pass (to a director) if the director suspects that you intended to open a 15-17 NT and have woken up due to partner's announcement.