HELSINKI A breakdown of the quadruple jumps, the judging system and the highest scores recorded ahead of the men's competition at the figure skating world championships in Helsinki which start on Wednesday.
Toeloop - Take off is from a back outside edge and landing is on the same back outside edge. The toeloop is the jump most commonly attempted and is often tagged on to a more difficult jump in combination. It is considered the easiest because skaters use their toe-picks to lift off and, once airborne, their hips are already facing the direction in which they will rotate.
Canada's Kurt Browning was the first person to land a legal quadruple jump -- a quad toeloop -- in competition in 1988.
Salchow - Named after inventor Ulrich Salchow, the take off is from a back inside edge and the skater lands on the back outside edge of the opposite foot.
American Timothy Goebel was the first skater to successfully land a quadruple Salchow and, in particular, a quad Salchow in combination, at the 1998 Junior Grand Prix Finals in Lausanne.
In 2002, Japan's Miki Ando became the first woman to land a quad jump, a Salchow at the Junior Grand Prix Final. That is still the only time a woman has successfully performed a quad in competition.
Loop - Take off is from the back outside edge and landing on the same back outside edge.
In 2016, Japan's Yuzuru Hanyu became the first skater to land a quadruple Loop -- also known as the Rittberger in Europe.
Flip - Take off is from a back inside edge and landing is on the back outside edge of the opposite foot.
In 2016, Japanese teenager Shoma Uno became the first skater to land a quadruple flip at an international competition.
Lutz - Named after Alois Lutz, it is a toepick-assisted jump where the take off is from a back outside edge and landing is on the back outside edge of the opposite foot.
In 2011, American Brandon Mroz landed the first successful quad Lutz in an international competition.
Axel - Named after Norwegian Axel Paulsen, it is the only jump where the skater launches into it going forward. Take off is from the forward outside edge and landing is on the back outside edge of the opposite foot.
It is considered to be the most difficult triple jump as it has an extra 180-degree rotation. Hence while other triple jumps involve three revolutions, a triple Axel has 3-1/2 rotations.
No quadruple Axel has been ratified yet.
The judging system has been overhauled since a scandal at the 2002 Salt Lake City Olympics when French judge Marie-Reine Le Gougne confessed to, then denied, scoring the pairs contest according to her federation president's dictum.
The French federation president, Didier Gailhaguet, was banned for three years and later resigned. Under pressure from the International Olympic Committee (IOC), officials awarded duplicate gold medals to Canadians David Pelletier and Jamie Sale who had originally been placed second.
As a result of the scandal, the old 6.0 scoring system was axed and replaced by an accumulative points system.
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There are two parts to judging in figure skating. A technical panel decides what has been performed (i.e. base value/difficulty) and competitors get a score for attempting a move, no matter how well, or badly, it is performed.
Skaters are then give 'grade of execution' score depending on how well, or badly, each element was performed. Points ranging from +3 to -3 are given.
Hence if a jump has a base difficulty value of 10, skaters can end up with seven points for the element if they messed up the landing or 13 points if the landing was perfect.
The total of all the elements scores gives the technical score.
The judges will award points on a scale from 0.25 to 10.00 with increments of 0.25 for the presentation score.
The skaters are judged on five elements -- skating skills, transitions, performance, composition, and interpretation of the music/timing (for ice dance).
Marks can be deducted for illegal moves, time violations etc.
A computer randomly selects the scores awarded by seven of nine judges. Of those scores, the lowest and highest are discarded and the remaining five are used for a final score.
The marks of all nine judges are displayed, so they do not know whether or not their marks contributed to the final total.
MEN'S WORLD RECORD SCORES
2014 Olympic champion Yuzuru Hanyu holds the record score for short programme (110.95), free skate (219.48) and total (330.43) -- all achieved at the 2015–16 Grand Prix Final.
At the world championships, the highest total was achieved by Spain's Javier Fernandez who amassed 314.93 in 2016. His free skate score of 216.41 is also the highest at the worlds.
The highest short-programme score at the worlds is held by Hanyu. He scored 110.56 in 2016.
(Compiled by Pritha Sarkar; Editing by Clare Fallon)