Definition of "prepositional"

Although we have concentrated on Prepositions which take zero Complements, NP Complements, or clausal Complements in our discussion above, there seems no reason in principle to exclude the possibility of Prepositions taking prepositional Complements. And it may well be that items such as those italicised below are Prepositions which subcategorise a PP Complement headed by of: (80) (a) He stayed at home because [of the strike] (80) (b) He fell out [of the window] (80) (c) Few people outside [of the immediate family] know (80) (d) %It fell off [of the table] (dialectal)

1988, Andrew Radford, chapter 7, in Transformational grammar: a first course, Cambridge, UK: Cambridge University Press, page 364