Through coach

In rail terminology, a through coach is a passenger car (coach) that is re-marshalled during the course of its journey. It begins the journey attached to one train, and arrives at its destination attached to another train.
Through coaches save their transit passengers the need to change trains themselves. They also increase the number of direct links offered by the train operator(s).
Most frequently in the form of sleeping or couchette cars, through coaches have commonly been used for long distance journeys, especially in continental Europe, although they are much less common now than they were in the early 1970s.
Example.
In 2010 and 2011, the Basel – Moscow sleeping car ( in 37 hours and 11 minutes) was attached successively to the following trains:
References.
"This article is based upon a translation of the as at February 2013."