Protection is needed against faults between circuits at different voltages (by segregation or overvoltage devices), against voltages in unused conductors (terminated and protected at both ends like live conductors), and against harmful influence between installations, circuits, non-electrical services and the structure; surge protection for lightning or switching is guidance, not a requirement.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.