Security controls are applied to back-end systems and, where back-end servers are critical to the provision of services, there are recovery measures in case of system outage; OWASP gives example controls (Table C1, threat 2.1: an attack stops the back-end serving vehicles; Table B2, threat 13.1: denial of service against the update server or network preventing rollout of critical updates).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.