References for connections
The connection reference is required to an other train. This is not sufficient.
- it should be more specific to a certain ocp (Berlin Hbf oben / unten)
- this ocp could be traversed more than once by the referenced train, so ocpTT would be more specific but is not referencable at the time
- a connection maybe holds only on certain dates, so a reference to a trainPart would be even more appropriate
With this ticket, the 'right' kind of reference should be implemented.