The symbol means pull out the cable knob and twist to lock in position, then twist back and let go to release.
It was nothing to do with application.
Cables of this type had multiple uses, so all of you on this thread have stated correct usages for this symbol and thus have correct answers depending on the scenario.
Uncle "Richard" Douglas has a Land Rover with big wheels that never gets stuck... until he breaks something so it won't go. Uncle Douglas always breaks something. - Anna Crowther at the Conclave 2012 (AKA Carburetor Neck)