If Jack format means any station that plays music that is a total hodge podge of times , eras and styles plus no jocks ----------- what do you call a station that runs jockless 20 hours a day and might play Beachboys, Diana Ross, Eagles, Madonna, Kenny Gee, Herman's Hermits ,Arlo Guthrie,Johhn Denver, Gilbert O'Sullivan,Four Tops, Bette Midler, and Frank Sinatra in one hour? The music is all over the place and its jockless. We got one right here now. I'd call it "Jack Lite" and it appearantly works.