minor switch

minor switch

[′mīn·ər ¦swich]
(electricity)
Single-motion stepping switch mounted atop the telephone connectors and most commonly used for the party-line selection.
References in periodicals archive ?
PLAY TWO UP FRONT MOVING from a 3-4-2-1 to a 3-4-1-2 may seem a minor switch.
The model features a longer bonnet, minor switch revisions including an upgraded GPS system, new door mirrors and a revised rear bumper.