Originally Posted by
corporate-wage-slave
Indeed a speciality of the Lufthansa group. You get their equivalent to TPs and Avios on these train trips, and on DB there is a mini section of the train that you are supposed to sit in, or rather the seat allocation does this. Handy for things like Cologne and the other locations within fast access of FRA.
They also have a special 'Air-rail' check-in area at FRA don't they, but I haven't quite worked out what purpose it serves.