Testing finds the faults a visual check cannot. On Class I equipment the protective earth path from the plug earth pin to the accessible earthed parts is checked, and on cord sets, extension sets, EPODs and portable RCDs the earth conductor is checked from the plug earth pin to the earth contact of every outlet, using the normative method in Appendix D. The earth path must measure 1 ohm or less. The test is best combined with the cord anchorage inspection.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.