The IERICS (Independent Engineering Review of Instrumentation and Control Systems) mission is a comprehensive engineering review service directly addressing strategy and the key elements for implementation of modern instrumentation and control (I&C) systems, noting in applicable cases, specific concerns related to the implementation of advanced digital I&C systems and the use of software and/or digital logic in safety applications of a nuclear power plant. The guidelines outlined in this publication provide a basic structure, common reference and checklist across the various areas covered by an IERICS mission. Publications referenced in these guidelines could provide additional useful information for the counterpart while preparing for the IERICS mission. A structure for the mission report is given in the Appendix. In 2016, this publication was revised by international experts who had participated in previous IERICS missions. The revision reflects experiences and lessons learned from the preparation and conduct of those missions.