The terminology has changed with the times. Chopped tops have become much more common, often being the first change made to a car. Such was not the case in the fifties and sixties, when there were four modifications by which a car would be deemed as a "Radical Custom", and judged accordingly at shows. These were: Chopping, Channeling, Sectioning, and Shortening. This was a definitive standard, and cars within the class generally (but not necessarily) carried a slew of other modifications, as was contemporary for the time. Cars with heavy body modifications that did not include one or more of the four changes mentioned were generally referred to as "Full-Customs" and "Semi Customs" This was often a discretionary determination. These were popular categories, and encompassed many famous customs. "Mild Customs" were the cars without major changes, either procedural or stylistic. Sometimes such simple changes as rounded hood corners could move you into "Semi Custom" status. But like I said, times have changed. Like Yogi Berra said, "The past ain't what it used to be!"