A three pole/three pole (or single pole) changeover is allowed where the board has a MEN link, with the set's neutral and earth wired per the Section 2 figures. A three pole/four pole device is allowed at a board with no MEN link and may switch the generator neutral, but should not be used in new installations. A four pole/four pole device in a main switchboard must not switch the normal supply neutral ahead of the MEN link; at a distribution board without a MEN link it may switch both the incoming submain and generator neutrals.
The graph holds this control, the 0 it maps to, and the evidence behind each claim, over MCP and REST.