Computer based systems are used to display the main parameters associated with critical safety functions of ligth water reactors such are: reactivity control, reactor coolant systems integrity, reactor core cooling and heat removal from primary systems, radioactivity control and containment integrity. This standard provides functional design criteria only and is only applicable to plant control rooms that were not designed in accordance with the IEC control room design standard. The safety parameter display systems consists of instruments, displays, hardware and computer software forming a stand-alone system or integrated into the control room information system.