blackshoe, on 2016-October-29, 16:37, said:
Well, yes, up to a point. If the defender has any reason from partnership agreement or experience to expect that the lead of an Ace might signify something other than the king, he has to say so. For example, would partner lead a singleton ace? Ace from ace doubleton? "Ace from ace-king" as an agreement usually comes about from discussions that start "king from ace-king *or* king-queen is ambiguous. Can we do better?" That discussion does not imply that when you decide "ace from ace-king" and partner leads the ace and you have the king, partner has departed from your agreements. If you have other agreements that might be germane, you must disclose them. Even if you think "obviously, everybody knows it might be a singleton". No, everybody does not know that.
If you have a specific agreement about whether you lead high or low from a singleton, you have to disclose it. I think it's ridiculous to have to disclose that you sometimes lead singletons.
If you disclose that you lead 4th best, do you also have to qualify it by saying that he might not necessarily be leading from a suit with at least 4 cards?