 The principle (LIN) combines forward-linearity (LIN-F) and backward-linearity (LIN-P) in a single condition. The resulting formula is, however, not sufficient to guarantee the connectedness of the temporal order. In other words, it cannot rule out disjoint linear time lines. It is also worthwhile to note that (IND\(_{G}\)) implies backward-discreteness and that (IND\(_{H}\)) implies forward-discreteness but not conversely. For instance, a time flow consisting of a copy of the natural numbers followed by a copy of the integers is backward-discrete, but it does not satisfy (IND\(_{G}\)).