 a perfectly good 4-d history, and it's entirely inside my 
history, but I sincerely hope there isnt ever a continuant with that 
as its extension.

One reply is that there are two different 'worlds' here: one 
concerned with spatiotemporal occupancy and relationships, the other 
concerned with things and identity, and they should be kept separate 
from each other (though closely related in many cases.) This might be 
a good way to approach a unified ontological framework, but I havnt 
thought of (or seen) 