The Security, Interoperability, Supportability, Sustainability and Usability (SISSU) is considered a part of the USAF IT LEAN process. SISSU is a comprehensive database of security controls (IA Controls) addressed in DoDI 8500.02 needed to complete the DIACAP process.
The SISSU questions includes everything from documentation of the system to physical security, to network security. To access the SISSU process in the EITDR one need an account and “stakeholders list” approval via AFCA/EV.
Security, Interoperability, Supportability, Sustainability and Usability are each considered disciplines. Each discipline is assigned a set of roles: producer, reviewer, validator, and approver. Once all of these roles have done their part on each of their applicable questions in a given discipline they can move on to the next phase. The phases are Define Need, Design, Build & Test, and Release.