ERTMS/ETCS implementation is going on all over Europe. After start­ing with pilot lines, countries are now opting for country-wide implementa­tion of ERTMS/ETCS. In this context locomotive manufacturers are pre­paring for the market for “European” locomotives equipped with ERTMS/ ETCS. Certification by Notified Bodies is required by European legislation. The rules for the assessment process are laid down in the Technical Specifi­cation for Interoperability for Control, Command and Signalling. The experi­ence with the application of the rules of the TSI is the subject of this article.