|Boolean values: yes or no, true or false, 1 or 0
If set to yes, this flag forces a=yes building to only build VehicleTypes with a corresponding Naval=yes flag set. This flag serves as the only real logical distinction between a land-based vehicle factory and a naval-based ship factory.
Naval=yes also prevents this BuildingType from being placed on non-Water tiles, or being deployed from a vehicle on non-Water tiles, regardless of the value of WaterBound.
If set to yes, determines that this vehicle can only be built by a factory with Naval=yes set.
Additionally, Naval=yes is used to designate what is considered a "naval" target forlogic.
NCO Bug Warning
The cause of the NCO bug is, indirectly, due to the developers' decision to treatand land-based vehicles as members of the same VehicleType class, rather than creating a separate class. Shipyards are therefore classed as Factory=VehicleType, just like War Factories. This means the game will determine that you can build the land-based vehicles when you don't have a War Factory but do have a Shipyard, and vice versa for vehicles.
The result of this is that, unless you set all ground vehicles to have aof at least one of the War Factories and set all units to have a of at least one of the Shipyards, you'll get the NCO bug when you own one of the factories but not the other. You can add other prerequisites as well if you like, but all units must include a of a factory of the appropriate kind. makes this difficult, since a satisfied causes to be ignored. If you set to something other than the appropriate factory, you'll get the bug. So it's best to stay away from this tag where possible.