This link explains how the intelligent ticket trial has operated in Dresden. 

There ae some more details on this site.  It is in German - but some of the diagrams are helpful even if your knowledge of German isn't too good: ALLFA ticket - how it works

The Dresden system uses 'be-in, be-out' technology, where passengers are automatically detected by the system.  The thinking in the West Midlands is that it would still be important to show the bus driver (for example) that you have a valid ticket when boarding.  This refinement would be described as 'check-in, be-out'.

Only by recording when a passenger gets off the bus, train or tram, can the system record useful data for journey planning and reimbursement of private operators.  A 'check-in, check-out' system could also do the job - but that would require passengers to electronically stamp their own ticket.  The advanced 'check-in, be-out' favoured by the West Midlands would ask the passenger to validate or show their ticket when boarding, but then record the end of their journey automatically.

See also these two links, which are to PDF files of news releases - in English.

Innovation in electronic ticketing (technical note)