are ephemeral. The TA has frequently shifted lettered routes from one branch line to another, and introduced, changed or deleted letters, making a description like "the D train" meaningless. The D service has been on three completely different Brooklyn branch lines since 1954. K was introduced for a service on the Broadway-Brooklyn Line but was later used for the IND Eighth Avenue Line local which had formerly been AA. The same lettered or numbered lines may have different destinations by time of day, despite a largely successful effort to minimize this problem. Elimination of double letters On June 25, 1979, the former color scheme was scrapped, and the TA settled on the more coherent policy of assigning the same color to every service on each Manhattan mainline, as well as the color lime green for the IND Crosstown Line, which does not enter Manhattan. The same colors are still used today. Nevertheless, no New York subway line is officially referred to by its color, e.g., BMT Broadway Line services as the "Yellow Line." While referring to lines by their color, as is common in some other cities, is a convenient shorthand for the regions of Manhattan where lines and colors are relatively unambiguous (from roughly Houston Street to 50th Street, and further uptown for the "red" and "green" lines), this practice would be confusing outside of that region (due to multiple services being assigned the same color). On May 5, 1985, the last significant change in route identification policy was made after the TA had decided in 1981 that the single and double letter system of the original IND was no longer meaningful, given that there were many services that were express for part of their route and local for other parts. In most cases, this was accomplished by simply eliminating the second letter in route designations. There is no longer a letter designation for specials (formerly S). By the 1990s, the TA were moving steadily toward using traditional line names on maps and especially on signage. All of the southern Brooklyn subway lines now show the traditional line names (except for the BMT Fourth Avenue Line) in order to distinguish between services going to Coney Island via different lines. On BMT/IND equipment branch line names frequently appear on operating trains, in addition to the route letter. R32 equipment with rollsigns, for example, may read: Newer rollsigns on R40 up