The FI must make all reasonable effort to maintain high availability for critical systems and must ensure the total unscheduled downtime of each critical system affecting operations or customer service does not exceed 4 hours in any rolling 12-month period. Per the FAQs, partial or intermittent disruption counts toward downtime, outages recovered transparently by a high availability configuration do not, and unscheduled downtime should be recorded per critical system.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.