Expanding Reading（拓展阅读）
Passenger Train Numbers
Every train has an identification number of two to four characters.The first character can be alphabetic or numeric，while the second to fourth characters are all numeric.
Trains are classified as up trains and down trains.Since Beijing is regarded as the center of the railway network，the train from Beijing is the down train，while the train towards Beijing is the up train.Trains that do not go to Beijing are designated up or down based on their direction:south and east are up，north and west are down.Down trains use odd numbers，while up trains use even numbers.
The first character of the train number usually indicates the class of the passenger train，often determined by the speed and number of stops the train makes along the way.There are several alphabetic prefixes.
G means high-speed train.
“G”is the first letter of“Gaosu”，literally meaning“High Speed”(EMU).It can run very fast at a top speed of 350 km/h.All high-speed trains in commercial use are named CRH in China.
CRH
C means inter-city high-speed train.
“C”is the first letter of“Chengji”，literally meaning“Inter-City High-speed Train”.This kind of trains run between two big cities with the highest speed of 350 km/h.
D means EMU train.
It is available after the sixth rise in speed of the railway in April 18，2007.All the trains have soft beds or seats.The top speed is 250km/h.
Z means direct express train.
Though its name in Chinese implies a“non-stop”train，most of these trains have several stops between the two stations.Most of the Z trains start in the evening and reach the destination in the next morning.
T means express train.
It has a limited number of stops along its routes，only in major cities，or in some instances for refueling.This kind of train is usually more crowded than direct express train.
K means fast train.
This kind of train is slower than“Z”and“T”train with more stops on route.The top speed is 120 km/h.
Ordinary fast train.
It is slower passenger train that stops at around half of the stations along the way，resulting in longer travel time than the fast train.It is indicated by a numeric prefix from 1—5 and has four digits in its number.
Ordinary train.
The ordinary train，often simply referred to as slow train，has as many stops as possible，and is often the preferred choice for rural workers to return their home villages.It is indicated by a numeric prefix from 6—9 and has four digits in its number.
Temporary train.
This is not listed in the official train schedule，but added when necessary.It is only available in rush hours such as during the Spring Festival.