The scope of this document is the definition of the functional interface between TDC and other train systems. These ??Other Train Systems?? are the train systems interfacing with the TDC excluding the displays (CLC/TR 50542-2)@ ETCS/STM onboard (Subset-121) and already designed class B ATP systems. The functional interface deals with data exchanged between TDC and these train systems. The TDC is defined in document CLC/TR 50542-1. NOTE The conversion of physical signals into numerical representation is out of scope