[Users] nature of Cactus

[Jan Hegewald]

Hello all,
I am new to Cactus and it is not clear to me where the limitations of  
Cactus are.
The Cactus users guide sometime talks about a "grid" and "grid  
points" etc. From this I got the impression that thorns always  
operate on some kind of uniform lattice. Is that true?
I am looking for a framework which can connect different legacy  
simulators, e.g. a car traffic simulation and a pedestrian movement  
simulation. Is Cactus suited for such things?

Many TIA,
-- Jan