One of the things that I find interesting about the railroad game is its rather unique culture. For example:

Despite the fact that all new American locomotives have the unit stencilled in at least one obvious location in the cab, I am amazed that operating crew members see the need to duplicate the number multiple times-using either a 'magic' marker or paint marker-usually on the control stand or desk. In my photo files, I have a photo of an in-service CSX GE new enough to have been painted yet-but with the unit number written in FIVE different locations.

In contrast, check out the following link as to how a certain Russian locomotive builder deals with the issue:

http://russiannarrowgauge.com/newgaller ... 770&LNG=EN

DPK

This is usually done because when you're bone-tired and numb after many hours of sitting in that cab, it makes it easier to note which unit is the leader when you're talking to the dispatcher or RTC. There is usually lots of other grafitti also, ranging from witty to inane.