define 'the world'...
originally, external bsp objects were going to be used for doors/plats/etc, and should thus be equivelent to inline models. No pvs required, but you potentially need everything else, including lightmaps, however awkward they are.
Even pickups have full collision/hulls/etc.
cl.worldmodel. if its NULL, then either the server is loading, or the current model is world.
Supposedly.
if sv.active is true, then any bsp loading is on behalf of the server, and the server's sv.worldmodel could be used instead. its horrible, I know.
FTE uses this, but only for texture replacements.
reckless, q2 only supports a single bsp file at any one time. inlines are not the issue here.