[gurps] Building a VehicleML

[Onno Meyer]

> >I want to declare one of the categories as "main category",
> >so that "interstellar" ships may be found in an "aerospace"
> >search, but only get listed once in a table-of-contents.
> 
> I have been think of a category system
> that splits the types of craft up (but still allow multi-type crafts like
> seaplanes)
> groundcraft (cars, bus, bikes, etc)
> hovercraft (ground effect crafts)

Do they need a special category? Call them amphibians
(ground/water) since they do not really fly. Of course
I envisioned to call amphibians either ground-capable 
watercraft or water-capable groundcraft, while a hover
does both equally well. OTOH, real-world hovercraft 
tend to be used over water.

> aircraft (planes, airships, etc)
> watercraft (boats, ships, etc)
> underwatercraft (submarines, etc )
> spacecrafts ( spaceships, etc)

aerospace = capable of transition from air to space
space = capable of sublight flight in space
interstellar = capable of faster than light flight

> if the GUID is also the file name there needs to be a limit on how long
> the GUID is

GUIDs are always 20-digit hexadecimal numbers. Using them 
as a filename is a bad idea, I have a real-world project 
where we do that, and debugging is kind of awkward.

As written, the XML format allows one or more vehicles per
file, so there is a good reason to identify vehicles within
the file.