SetReplaceSystemParameters gives the list of parameters that can be used as keys in generators such as
GenerateMultihistory:
In[] := SetReplaceSystemParameters[MultisetSubstitutionSystem]
Out[] = {MaxGeneration, MaxDestroyerEvents, MinEventInputs, MaxEventInputs, MaxEvents}The entire system spec including the rules can be passed as well (rules don't affect the result):
In[] := SetReplaceSystemParameters[AtomicStateSystem[a_ :> a + 1]]
Out[] = {MaxGeneration, MaxDestroyerEvents, MaxEvents}