Form 109 -- Classification and Description of Locomotives and Tenders -- provides detailed specifications about every class and subclass of locomotive and tender. Its used faded as diesel locomotives took over. Each time the form was revised, its alphabetic suffix was incremented.
Form 109-C, May 1, 1902
Form 109-D, March 1, 1904
Form 109-F, June 1, 1912
Form 109-G, June 1, 1916 [or 1918]
Form 109-I, December 20, 1933
Form 109-J, May 15, 1948
Form 109-K, June 2, 1952
Form 109-L, September 1, 1956
Form 109-M, July 1, 1960
