Hi all, Both John and Henrik provided feedback on v4 of the document (thank you very much!), and the three of us had a vivid email discussion earlier this month on why and how to structure the security attributes in the NSI message header. The discussion is not finalized, but I updated the document with the latest ideas. Please find attached version 5. This document is still far from finished. Big question still remains: how does the group wants to move forward with this document? Cheers, HansT.