The 6.0 system was divided into "technical merit" (in the free skate), "required elements" (in the short program), and "presentation" (in both programs). The marks for each program ranged from 0.0 to 6.0, the latter being the highest. These marks were used to determine a preference ranking, or "ordinal", separately for each judge; the judges' preferences were then combined to determine placements for each skater in each program. The placements for the two programs were then combined, with the free skate placement weighted more heavily than the short program. The individual with the lowest sum of the factored placements was declared the winner.
The 6.0 system was a ranking system. Skaters were ranked in comparison to each other in marks ranging from 0.0 to 6.0, with 6.0 being the highest possible mark. It was first introduced at ISU congress in 1901. Until that year skaters's marks ranged from 0 to 5. A 6.0 mark for technical merit was extremely rare.
The 6.0 system went through various versions in terms of how scores were tabulated and compared with each other. Until 1980, for example, each judges' weighted scores from each phase of the competition were added together before computing ordinals, instead of using factored placements. Because compulsory figures were scored using a wider range of marks than the short program or free skating, this system allowed skaters to take a large lead in that segment of the competition, which made them effectively unreachable in later segments. The system of factored placements, in which ordinals were computed for each competition segment separately and factors applied to the relative placements rather than the raw marks, was proposed as early as 1971 by former Hungarian champion and World Referee Pál Jaross, and finally adopted for the 1980-1981 season. In 1998, the method by which placements within a segment were computed was changed from "best of majority" -- ranking skaters by the highest ordinal for which they received a majority vote of the judges—to a system of "one-by-one" comparisons between the ordinals of all the skaters.
6.0 as a mark 
While the 6.0 mark by itself did not mean anything out of context, it was often used as a sign of perfection. British ice dancers Jayne Torvill and Christopher Dean earned nine 6.0 scores for artistic impression at the 1984 Winter Olympics, and remain the only ice skaters to ever achieve that score in the Olympics.
- Loosemore, Sandra (1998-12-02). "It's the presentation, stupid". CBS Sportsline. Archived from the original on 1999-04-29.
- "The 6.0 System". U.S. Figure Skating. Retrieved September 4, 2006.
- Absaliamova, I. V. (1997). Stoletniaya Istoria Chempionatov Mira po Figurnomu Kataniu na Konkach (Odinochnoe Katanie) (in Russian). Moscow: FON. p. 122. ISBN 5-89022-046-2.
- Tarasova, T. A. (1985). "Мой мир, мое фигурное катание". Chetyrie Vremeni Goda (in Russian). Moscow: Sov. Rossia. p. 176.
- Benjamin T. Wright, Skating in America, published by U.S. Figure Skating
- "Worlds: Contemporary Calculations", Skating magazine, May 1971
- "1984: British ice couple score Olympic gold". BBC News. 1984-02-14. Archived from the original on 31 January 2008. "They scored 12 out of 18 possible sixes for their free dance and the maximum possible of nine sixes for artistic impression."
- "Meeting of the ISU Congress", Skating magazine, November 1959