Contains the definitions and explanation of terms that are used in parts 1 to 7 of this standard. 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. Has the status of a basic safety publication in accordance with IEC Guide 104. The contents of the corrigendum of April 1999 have been included in this copy.