 Each piece of rolling stock is allocated a six-digit number, a check digit, and a letter to indicate its allocation.When the RFFSA began to repaint its locomotives of both Metric and Irish Gauges in Ash Grey and Lemon Yellow (1994–1996), the numbers were relocated towards the radiator section of the locomotive.In some cases, the locomotives were baptized with names, municipalities, states, or cities of there they respectively operated.