RULE 70 STARTING TIME.  (a) Regularly assigned engineers shall have a fixed starting time, and the starting time will not be changed without at least 48 hours' advance notice.  

(b) Where three 8-hour shifts are worked in continuous service, the time for the first shift to begin work will be between 6:30 AM and 8:00 AM; the second 2:30 PM and 4:00 PM; and the third 10:30 PM and 12 midnight.  

(c) Except in case of emergency, in calling extra shifts in yards where continuous yard service is maintained by regular yard crew assignments, the extra shifts shall be started within one of the three periods named in Section (b).  

(d) Where two shifts are worked in continuous service, the first shift may be started during any one of the periods named in Section (b).  

(e) Where two shifts are worked not in continuous service, the time for the first shift to begin work will be between the hours of 6:30 AM and 10:00 AM and the second not later than 10:30 PM.  

(f) Where an independent assignment is worked regularly, the starting time will be during one of the periods provided in Sections (b) or (e).  

(g) At points where only one yard crew is regularly employed, they can be started at any time, subject to Section (a).  

(h) Where mutually agreeable, on account of conditions produced by having two standards of time, starting time may be changed one hour from periods above provided.