this section :
4.4 OPC UA relationship to site security
OPC UA security works within the overall Cyber Security Management System (CSMS) of a site. Sites often have a CSMS that addresses security policy and procedures, personnel, responsibilities, audits, and physical security. A CSMS typically addresses threats that include those that are described in 4.3. They also analyse the security risks and determine what security controls the site needs.

need to be updated to include a reference to the NIST document that cover the same items (may also be an IEC document)