This part of IEC 61375 applies to the applications in trains@ i.e. it covers the application profile for functions belonging to the Train Control and Monitoring System (TCMS). The application profile is based on the TCN communication system for the data communication between consists of the said trains. This document provides for a data interface with parameters and addressing of TCMS functions based on the communication profile laid out in IEC 61375-2-3. This document is applicable in rolling stock requiring interoperable coupling and uncoupling. This part of IEC 61375 may be additionally applicable to closed trains and multiple unit trains when so agreed between purchaser and supplier. The applicability of this part of IEC 61375 to the train communication network technologies as defined allows for interoperability of individual consists within trains. The data communication systems inside consists are not covered by this document and are given only as example solutions to cope with the said TCN. In any case@ proof of compatibility between a proposed train backbone and a proposed consist network will have to be brought by the supplier. Special backup functions@ which are used in cases when the train backbone is in a degraded condition are not in the scope of this document.