In China, trains traveling at speeds of up to 200km/hour or more are called "dynamic trains". It is a combination of powered and non-powered vehicles in accordance with predetermined parameters, so it can be summarized that a rolling stock is a self-powered, fixed formation, with driver's cabins at each end of the train for driving operations, equipped with modern service facilities for passenger trains. High-speed trains are classified according to speed, usually referring to trains with a speed of 250km/h or more. Vehicles with power are called locomotives, and vehicles without power are called trailer sets. Dynamic train set technology originates from the subway, which is a kind of power dispersion technology.