Electrical Connectors, Feeder, Flat
In the US, a main power cable to an installation is known as a feeder.
A lightweight timber frame covered with scenic canvas. Now usually covered with plywood or hardboard and consequently not so lightweight. Most theatres have a range of stock flattage made to a standard size, and re-used many times. A Rail is a horizontal batten within a flat. A Stile is a side or vertical piece within a flat. A Sill is the bottom rail of a flat.