The following standard shall be followed in order to satisfy the Safety Integrity Level (SIL) requirement allocated to the E/E/PE functions of the system :EN 50129:2003 Railway applications – Communication, signalling and processing systems – Safety related electronic systems for signallingEN 50126-2: 2017 Railway applications –The Specification and Demonstration of Reliability, Availability, Maintainability and Safety (RAMS) - Part 1: Systems Approach to Safety"