Genre, at least as someone sees it -- either the operator of the store if it's a mom-and-pop operation or corporate management in combination with the record companies if it's a chain outlet. Once songs of any kind are selected for airplay on radio stations and given an umbrella word to describe that kind of songs being played, that's a format.So when I go to a record store and I see the alternative section is that a genre of music or a radio format?