SELV or PELV may provide both basic and fault protection where the source is limited to 50 V (a.c.; 120 V for ripple-free d.c.), circuits are segregated from each other and from higher voltages, SELV live parts are not earthed or connected to other circuits' earths, and PELV live parts are insulated or behind barriers unless below set lower voltages (Clause 7.5 has the detailed rules).
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.