This International Standard provides requirements for the software of computer-based I&C
systems performing functions of safety category B or C as defined by IEC 61226. It
complements IEC 60880 and IEC 60880-2, which provide requirements for the software of
computer-based I&C systems performing functions of safety category A.
It is also consistent with, and complementary to, IEC 61513. Activities that are mainly system
level activities (for example, integration, validation and installation) are not addressed
exhaustively by this standard: requirements that are not specific to software are deferred to
IEC 61513.

Since a given safety-classified I&C system may perform functions of different safety
categories and even non safety-classified functions, the requirements of this standard are
attached to the safety class of the I&C system.
This standard takes into account the current practices for the development of software for I&C
systems, in particular:
• the use of pre-developed software, equipment and equipment families that were not
necessarily designed to nuclear industry sector standards;
• the use of dedicated “black-box” devices with embedded software;
• the use of application-oriented languages.
This standard is not intended to be used as a general-purpose software engineering guide. It
provides requirements that the software of I&C systems of safety classes 2 or 3 must meet to
achieve system nuclear safety objectives.