Unlike three turns and brackets, where the entry and exit edges follow the same curve, in a rocker, the entry and exit are on opposite curves.
Another way to look at it is that a rocker is similar to the entry of a three turn combined with the exit of a bracket.
(The opposite combination is called a counter turn.)
While rockers are sometimes used to perform a simple change of direction, they more commonly appear in step sequences and in compulsory dances in ice dancing.
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