A yardman will be required to give notice of his desire to lay off at least three (3) hours in advance of the starting time of his assignment, except in case of sickness. In such cases, sufficient notice must be given to the proper officer of the railroad so that an extra man may be notified in time to prevent an engine working short handed.
Extra yardmen will not be required to report for duty if provided with telephone facilities, but will be called as nearly as possible one (1) hour and thirty (30) minutes before beginning the assignment.
Extra yardmen will not be marked on vacancies at the time the board is marked up, but will be called as nearly as practicable one (1) hour and thirty (30) minutes prior to the starting time of the shift on which the vacancy exists.
