Cyberyeti, on 2012-November-21, 17:23, said:
W is entitled to ask, he may not know what the 2♦ bid is and there are other possibilities (precision style for example) where he may want to double. This gives E UI, but most likely that his partner has diamonds, as this seems the most likely holding he'd be bidding over some other sort of 2♦.
...
What hands would act over other types of 2♦ bid, but not over a multi ?
I don't think that there are any 2
♦ bid that actually show diamonds that are alerted instead of announced in the UK. Maybe some sort of weird upside-down Lucas, but this would be extremely uncommon.
I think that West wished to know whether he would have another chance to act. And if he was told that 2
♦ was Multi, he might ask more, because some players call it Multi when it is weak only (what is that actually called, David?).
To answer the above question: with this hand, West may have been interested in bidding 2
♥ for takeout if 2
♦ was a bid that was usually a weak-two in hearts; may have considered doubling to show "interest" if the bid showed both majors; may have just wanted to follow the auction (and be ready with explanations/alerts).
I know not with what weapons World War III will be fought, but World War IV will be fought with sticks and stones -- Albert Einstein