This International Standard specifies requirements and makes recommendations for the design, integration and validation of safety-related electrical, electronic and programmable electronic control systems (SRECS) for machines (see Note 1). It is applicable to control systems used, either singly or in combination, to carry out safety functions on machines that are not portable by hand while working, including a group of machines working together in a co-ordinated manner. NOTE 1- In this standard the term electrical control systems is used to stand for electrical, electronic and programmable electronic (E/E/PE) control systems and SRECS is used to stand for s