(6)Where any group is required to work on a system of shifts and the relays are not to be subject to predetermined periodical changes of shifts, the manager of the factory shall fix the periods during which each relay of the group may be required to work. tc "(6) Where any group is required to work on a system of shifts and the relays are not to be subject to predetermined periodical changes of shifts, the manager of the factory shall fix the periods during which each relay of the group may be required to work."
