Additional requirements for safety integrity level

2 A safety instrumented function of safety integrity level 4 shall be permitted only if the criteria in either a), or both b) and c) below are met. 

NOTE Such experience should have been gained in a similar environment and, as a minimum, oomponents should have been used in a system of comparable complexity level. 

NOTE The data should be relevant to the proposed environment, application and complexity level. 

No reproduction or networking permitted without license from IHS 

3 Additional requirements for safety integrity level 4 9.3.1 No further guidance provided. 

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