Uniform Code of Operating Rules, a rule book that was adopted by a collection of railroads. There are two different UCOR rule books:
United States : used by C&EI, GH&H, HBT, MKT, MP, CRIP, FWD, SSW, UT. The last issue was in 1968, it is commonly called “UCOR 1968” to differentiate it from the Canadian rules.
Canada : Used by the CN and CP, it is commonly called the “UCOR 1962” to differentiate it from the American rules.