mycroft, on 2021-February-26, 11:07, said:
The classic case is describing a 5♥ KC response as "2" or "2 keys" and seeing who asks about the Queen. I have even heard people, whose opinions I respect, say that doing everything right makes the information you get UI - for instance my bugbear of an unAlerted 2♦ opener: "Find out which opponents asks, play them for 13 balanced"[1]. To which I say, "why not? Her partner will." (and yes, I know it's explicitly UI to her)
[1] or, as I found out recently, ♦AQT9x and a card. Luckily partner had obvious calls and she was able to show "decent hand, diamond stop" in the legal auction. If she hadn't been V vs NV, she probably should have passed the double, though, which would have immediately prompted a director call (which would have gone nowhere, because partner did in fact have a 100% double). I will admit that my "NAT PRE, and I would have Alerted anything else, and you know that" was not one of the highlights of my bridge propriety career. Not, however, *wrong*).
Part of the line could be to insist on a system (convention) card, no?
I don't play seriously on BBO, but my quickly written card does say that that 5♥ KC response denies Queen and that 2♦ is 5+ weak.
As a Director I am skeptical both of explanations that contradict the card and of pairs without one.