 In many branching time models C will just be the set of all maximally ordered linear subsets in (TIME,\(\le)\). In such cases C will not be an independent parameter of the model. In other cases, however, there will be some additional restrictions on C, i.e., it will be a proper subset of the set of all maximally ordered linear subsets in (TIME,\(\le)\). In some branching time models there will also be introduced a relation of (counterfactually) co-temporaneous moments. Given that such a relation is an equivalence relation, it may give rise to the definition of instants as equivalence classes of co-temporaneous moments.