下行

Verb

 * 1) to go downstream
 * 2)  to go down to the south
 * 3)  to go in the opposite direction of the capital (Beijing)
 * 4) to send to lower authorities as of documents
 * 5)  to fall

Usage notes
In Mainland China, trains going in the opposite direction of Beijing (i.e. "down" trains) have odd-numbered train codes.