The Belgian high speed lines L4 and L3 are built to achieve a performance of up to 300 km/h and 3-minute headway under continuous speed supervision provided by ERTMS/ETCS level 2. ERTMS/ETCS level 2 is supplemented with ERTMS/ETCS level 1, which takes over in case the former experiences a failure while offering parallel operations in a mixed level application. The lines L4 and L3 are divided into three structural and two functional subsystems. These subsystems are subject to EC verification against their respective Technical Specifications of Interoperability (TSI) of Directive 96/48/EC. This article describes the organisational and review framework set out by Infrabel and under which the EC verification of the Control-Command & Signalling subsystem through module SH2 (Full Quality Management with Design Examination) is managed and draws conclusions regarding key problems, concerns and issues arising from the implementation of the TSI and the ways they are addressed.