ETT # 20, 10/27/57
ETT # 24, 04/26/59
ETT # 3, 07/30/78 lose leaf pages (6) to be inserted into
rulebook
ETT # 5, 10/26/86 loose leaf pages only
ETT # 3, 10/29/89 PAGES IN BINDER
POTOMAC YARD SPECIAL RULES (B&O, C&O, PRR, RF&P, SOUTHERN) 03/15/61 with undated updates (2 pages)
PTT 04/26/70