 In less straightforward cases, however, the proposition expressed by P* may have to differ from that expressed by  P.[1]  Fictionalists may also employ other biconditionals when constructing their fiction — one example is a biconditional to ensure that every proposition that is (really) true is according to the fiction true in the actual  world.[2]  A modal fiction may require more contents than those yielded by such biconditionals: what other contents the fiction of possible worlds might contain is an important question, and one unsurprisingly which different modal fictionalists will answer differently.