Years ago DB published a list of 'Kurswagen', these are/were coaches usually connected to various different trains during their run but not necessarily originating or terminating at a scheduled/designated line.
For example one could book/reserve a seat in a Kurswagen 'Freiburg/Leipzig' on a train running actually Basel/Amsterdam. The Kurswagen would first travel on this train to say Karlsruhe, then being hooked onto one to Stuttgard-Nuernberg and on another one from there to Leipzig. This is just hypothesis.
Although, the question here is, does a 'Kurswagen List' exit, plus would there be one list for all Europe rail travel
This is a big order, and thanks.