The BMT introduced numbers for all its services in 1924 but these were mostly for map purposes, since none of equipment displayed line numbers until the D-type Triplex cars were introduced as prototypes in 1925, and then in production in 1927, and these only on the front of the trains (but after 1953 on R16 equipment also on the sides ). In 1931 these numbers were also used on 20 IND R1 cars when they were tested by the City on BMT lines, and also on 140 of these cars from 1949 to 1955 while in BMT service as well.