See also:

BMW Maintenance System
The maintenance system directs you to required maintenance measures and thereby supports you in maintaining road safety and the operational reliability of the vehicle. ...

The concept
The parking brake is primarily intended to prevent the vehicle from rolling while parked; it brakes the rear wheels. ...

Safety switch for the rear
Press the button on the driver's door if children are being transported in the rear. This locks the rear window switches so that the windows cannot be operated from the rear: safety switch. ...