Arthur Murray mistakenly codified the Lindy coaster step into its "Western Swing" curriculum as having the follower simply continue to face the leader and step back, together, and forward toward the leader during the last two beats of a pattern.
In the 1950s, West Coast Swing was popularized by Skippy Blair, who within time introduced the Anchor Step for use during the last two beats of each rhythm pattern for both leaders and followers.
Technically, Skippy Blair defined the anchor step as keeping the center-point-of-balance (solar plexus) behind the heel of the forward foot throughout the last two beats of each West Coast Swing pattern, providing wide latitude for dancers to express themselves.
The name "coaster step" denotes original function of the step, which was to gradually diminish a partner's momentum through the last two beats of any pattern until the body has slowed enough to change direction or velocity easily without exerting too much force on either the dancer or the partnership.
[6] However, her written description variations of the second triple of the "Basic Throwout" includes the following, "On the 2nd 1-2-3 the girl can take a sharp turn LEFT...