RULE 56. BULLETINS—ASSIGNMENTS. Bulletins advertising vacancies in helper service, or the establishment of new stations at which engineers are to be assigned to helper service exclusively, shall designate the station at which they are to be assigned for service and said station shall be known as their home station. Engineers assigned thereunder shall be paid continuous time from the time they are required to report for duty at their home station until returned thereto, subject to Federal Tie-up rules.