I have disassembled a (single phase) mains outlet and found the usual L, N and ground cable connectors but to my surprise there is also a 4th connector labelled 'A':
Green/Yellow is ground, blue is neutral, black is live, but what is orange? Symbol above 'A' looks like some kind of a switch or breaker.
Front looks like this (Switzerland type J):
Going by the numbers on it this seems to be the main part: https://online-katalog.feller.ch/kat_details.php?fnr=87303.F.61 (sorry, no english version)