Train types/compositions

[Otto fon Shtirlits]

"Red Arrow" you wona say, right?
OK, I must confess that the train called by its point s of start and destination could be confused when it isn't accompanied with its unique number. Mentioning my childhood I see my Grand-fa calling his train exactly in the following form - Rostov-Moskva #20. By the way he never called it as "Tikhiy Don". There is another one situation relating trains working on service Moscow-Peterburg. All of then are called "Arrows" by residents of both capitals. In this case residents use only train number meaning one of them.
Regards.