Categories groups the category-level anchor entities that organize every other type in this atlas: Vehicles, Modes, Figures, Infrastructure, Concepts, Networks and Operators, Routes and Services, Engines and their siblings. Each anchor carries that type's own overview prose and lets a visitor browse into its subcategory tree from one starting point. This category is a structural convenience for the atlas's own organization rather than a transport subject, and excludes any entity that actually describes a mode, vehicle, figure or place, which belongs under its own type.