The most recent US vice-presidential debate had a rule saying that debate topics would not be released "ahead of the debate". Obviously, they know that certain topics are more likely to come up than others (everybody cares about economics and taxes; nobody cares about boxers or briefs).
In cases like this do the candidates actually go on stage without any information on what has been selected? I would have expected that they would be handed an agenda a minute or two before going out, just so they can understand the flow. Is that right or do they have no idea what the next topic is until the question comes from the moderators lips?