 Content descriptors are primarily applied to feature films with a minimum rating of "PG" as per the Motion Picture Association of America's ratings system or programs with a TV Parental Guideline rating of "TV-PG".Like the TV Parental Guidelines, which this system predates and is used alongside, the content ratings were established as a voluntary participation system, with the assigned ratings for each program determined by the individually participating subscription television networks.The system's creation was spurred by concerns from parents over the amount of violent content in television programs, particularly those seen on premium cable channels.