Throughout this book, I have assumed that adpositions (prepositions and postpositions) are not lexical categories, but rather functional categories. […] While this view of adpositions is far from unprecedented, it runs contrary to the more standard generative treatment, championed by Jackendoff (1977: 31-33), in which adpositions constitute a fourth lexical category, filling out the logical space of possibilities defined by the two binary-valued features +!/!!-!! mathsf N and +!/!!-!! mathsf V.