UIC classification of railway coaches – Wikipedia

The UIC classification system for passenger coaches is an international standard for designating the types of passenger coaches defined by the International Union of Railways (UIC).

Unlike the UIC type designation system for freight wagons, the design type for passenger coaches is only clearly defined by the wagon number, while the generic symbols are only standardized in a very rudimentary way. For example, the first class Eurofima wagons, which are actually completely identical in construction, are called Avmz (DB), Amoz (ÖBB, later Amz), A9u (SNCF), Am (SBB), A I6 (SNCB) or Az (FS), depending on the railroad. The UIC standardized number for passenger coaches was introduced in 1966.

The capitalized generic letters are largely uniform internationally, although various railroads have already used a large proportion of them in their national designations, such as the generic letters for German railroad carriages.

The lower-case letters for technical details, on the other hand, are the responsibility of the respective railroad company. To differentiate between different construction series with the same features, some railroad companies also assign type numbers.