A continuing problem in the forums is that people that ask questions don't mark which reply is the answer. As moderator I'd rather the questioner mark the answer, but sometimes I mark a proposed answer (even my own) to hopefully nudge the questioner.
Often a question is handled by someone expert in the situation (often themselves also a moderator), but there are many replies in the thread and as moderator I recognize that only the particular expert is really qualified to mark the correct answer.
In a similar situation when I am the "expert", I try to assist the other moderators my marking a proposed answer for my own reply. Sometimes, the only alternative is either for me to mark my own reply as "the" answer (which avoid as much as possible), or for
other moderators to guess.
A "proposed" answer is just that. The questioner can unmark it. And more than one reply can be marked "proposed answer". Even "the answer" could be one you disagree with.
Richard Mueller - MVP Directory Services