IEC 61511-1:2016 is available as IEC 61511-1:2016 RLV which contains the International Standard and its Redline version, showing all changes of the technical content compared to the previous edition. IEC 61511-1:2016 gives requirements for the specification, design, installation, operation and maintenance of a safety instrumented system (SIS), so that it can be confidently entrusted to achieve or maintain a safe state of the process. IEC 61511-1 has been developed as a process sector implementation of IEC 61508:2010. The contents of the corrigendum of September 2016 have been included in this copy.