It is a standalone standard but a companion document to ISA-84.00.01 (IEC 61511 mod) . It provides a risk-based methodology to answer a critical question: How much cybersecurity is enough for my safety system?
This is where enters the frame. Published by the International Society of Automation (ISA), this technical report provides a formal methodology to bridge the gap between functional safety (IEC 61511) and cybersecurity (IEC 62443). isa-tr84.00.09