Hacking applied a method involving the labeling of sequent members to the problem of giving a Gentzen-style system for S 5, called L5, formulated with strict implication and no special modal operator. The method was generalized to a labeling of hypersequents by G. Mints. In this paper, we show how this generalization eliminates an “anti-symmetry” in Hacking’s system and greatly simplifies L5. W...