Some markets indicate they will “resolve to a percent,” for example this one:

https://manifold.markets/Tsunombie/what-will-be-donald-trumps-favorabi?r=dGhlbWlnaHR5c2FsbW9u

What exactly does this mean?

If the market ends at X%, do YES positions payout X percent, and NO positions payout 1-X percent? Or do YES positions pay out 100% if X%>50%, and similarly NO positions pay out 100% if X%<50%? Or does some other thing happen?

If I want my market to resolve to a percent, do I need to take any special actions when I create the question? Or can I choose to resolve to a percent at the time of resolution?

100 mana for the best complete explanation of “resolves to a percent.” This can be split if the question is partially answered by multiple responses.