Parts subject to mechanical wear, electrical or environmental degradation or ageing that could create unacceptable risk if left unchecked too long can be reached to inspect, maintain and replace them, and parts likely to be replaced or adjusted are located and secured so that inspection, servicing, replacement and adjustment neither damage nor disturb nearby parts or wiring, checked by inspecting those parts and their location.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.