Provides information on the underlying concepts of risk and the relationship of risk to safety integrity (see annex A); a number of methods that will enable the safety integrity levels for the E/E/PE safety-related systems, other technology safety-related systems and external risk reduction facilities to be determined (see annexes, B, C, D and E) Intended for use by technical committees in the preparation of standards in accordance with the principles contained in IEC Guide 104 and ISO/IEC Guide 51. IEC 61508 is also intended as a stand-alone standard.The contents of the corrigendum of April 1999 have been included in this copy.