sentences:  This can occur when the customer wishes or needs to change trains several times, either with a view to travelling on a particular line (for example to connect with a faster train), or because of a desire to break a journey at a given station not directly on the 'expected' route.Passing through the same station twice is almost always forbidden, except where a rule or 'easement' allows it.These easements are exceptions to the acceptable routes which are otherwise explicitly defined, and are listed in Section E of the Guide for easy reference.