What does "interlocked" mean?

It was explained in another post. To withdraw the plug the supply
must be switched off. This prevents someone unplugging it on load.
Arcs from 16A equipment are not too bad, but this sort of socket
goes up to 125A, which would be much more impressive if not somewhat
frightening.


So if I just fit an RCD and an interlocked socket, I would have to
turn the supply off at the RCD to withdraw the plug? It's not enough
to turn off the switch on the kiln?