Stories and Maps: Postmodernism and Professional Communication

Take, for example, the campus phone book, unlike the map sent out as public relations material to parents, contains an extremely detailed map showing the locations of emergency call boxes on campus. The call boxes are shown in bright red to contrast with the black and gray of the other aspects of the map (buildings, compass directions, streets).

Why are the locations of emergency phone boxes shown on this map? (And, for that matter, what's not shown?)