From the rear cover:
Emperor's Vehicles has dozens of vehicles for land, air, and ocean adventuring.
From the Introduction:
The entries are divided into categories, each denoting an individual vehicle's capacity and function.
Categories are a combination of one of the following "capacities" and one of the following "functions." Not all combinations are used.
Capacities: Personal, Passenger, Carriages, Commercial, Industrial, Personnel, AFV, Gunship, Fighter, Bomber.
Functions: Wheeled, Tracked, Grav, Winged, Rotary Winged, Water, Submersible, Close Orbit.
Other categories not in combination: Beast of Burden, Destroyer, Rail, Dirigible.