The business must manage the risk of someone falling between levels where injury is reasonably likely, first by keeping the work at ground level or on solid construction so far as reasonably practicable, and otherwise providing a fall prevention device, a work positioning system or a fall arrest system in that order, with emergency and rescue procedures where a fall arrest system is used.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.