IEC 62279:2015 specifies the process and technical requirements for the development of software for programmable electronic systems for use in railway control and protection applications. It is aimed at use in any area where there are safety implications. These systems can be implemented using dedicated microprocessors, programmable logic controllers, multiprocessor distributed systems, larger scale central processor systems or other architectures. The main technical changes with respect to the previous edition are as follows: - addition of requirements on software management and organisation, of definition of roles and competencies, deployment and maintenance; - addition of a new subclause on tools based on IEC 61508-2:2010. This publication is to be read in conjunction with IEC 62278:2002.