VehicleTypes
This page should correctly be named "[VehicleTypes]"; it is wrong due to technical restrictions.
This section of rules(md).ini lists all VehicleTypes the game should be able to use. VehicleTypes not listed here cannot be accessed by the game - they don't exist.
Okay, that's actually not entirely true. It seems like objects that are parsed by other objects, like BuildingTypes being called by DeploysInto or InfantryTypes being referenced by Enslaves are added into the internal *Types arrays as well. However, there is no reason to rely on this method, and you really, really should add your objects to their respective lists.
And you shouldn't expect help on an unlisted object from anyone, either.