Verification and Simulation share many issues, one is that simulation
models require validation and verification.  Both are treated in the
literature at a rather high level and seem to be more an art than
engineering. This talk considers discrete event simulation of
stochastic models that are formulated in a process-oriented language.  
The ProC/B paradigm is used as a particular example of a class of
simulation languages which follow the common process interaciton
approach and show common concepts used in performance modeling,
namely a) layered systems of virtual machines that contain resources and
provide services and b) concurrent processes that interact by
message passing and shared memory. The talk identifies typical faults
in simulation models that were developed to model logistic systems, 
it shows ways to support a user in verifying a simulation model, and 
it indicates challenges for further research.