2 12 0 steam Locomotive

It is very likely that each country has its own system of marks, numbers and abbreviations that are different from those in other countries.
For example, in Czechoslovakia, Vojtěch Kryšpín, the chief designer of the ČKD locomotive department, designed the marking system. This designation was gradually introduced from 1921, in 1925 all ČSD locomotives and even locomotives of some private railways were marked with it.
Kryšpín's designation was used until January 1, 1988, when it was replaced by a new system established by the International Union of Railways (UIC) by its decree and is valid for all its members. It assigns a unique twelve-digit number to each railway vehicle (freight, passenger and traction) by which the vehicle is identified in service.

The twelve-digit number is the so-called 'speaking' - it serves not only to identify the vehicle, but is also divided into groups of digits that carry a coded meaning.

The system established by the UIC was adopted as the identification of railway vehicles in service in the European Union by a decision of the European Commission, first by issuing a decision of 2006, the so-called TSI - Traffic Operation and Management, which fully entered into force in the European Union in 2010. This was replaced in 2012 by a new edition (already common for both conventional and high-speed systems), which brings the issue to the vehicle register issue addressed by other TSIs in the form of a change (omitting some non-identification provisions, in particular letter series).

The 12-digit number is called the European Vehicle Number (EVN) in TSI (2012) terminology.