It’s totally off topic but there used to be a vast array of proprietary and non standardised connectors used as appliance couplers. Often manufacturer specific or ad hoc standards that emerged. They were largely standardised by the IEC over the years.
There’s an website maintained by Oof Oud that describes, explains and chronicles the evolution of the world’s mains power plugs, sockets and couplers - there are a lot of them!
https://www.plugsocketmuseum.nl/ApplConn_overview.html
There’s an website maintained by Oof Oud that describes, explains and chronicles the evolution of the world’s mains power plugs, sockets and couplers - there are a lot of them!
https://www.plugsocketmuseum.nl/ApplConn_overview.html