In any form of swing dancing, the Anchor is the final Unit (2 beats) of any step pattern. For 8 beat patterns, the Anchor would be on counts "7 & 8." for 6 beat patterns, the Anchor would be on counts "5 & 6." There are several different forms of an anchor which will work with fast dancing such as Lindy Hop - some of which are defined as follows.
Count: 7 & 8
[ X X X]
Foot L R L
Dir B T f
F-Pos 4 1 4
Turn **>
* = 1/8 Lt
Verbal: [7 & 8]
What is a Coaster Anchor
Some people just define it as a Triple Rhythm Unit in which the the dancer steps Back, Together, Forward. That is what many dancers do. However, to execute a full Coaster Anchor, the dancer includes some swivels.
Counts "7 & 8": Prior to Count "7," the follower will execute a slight swivel to the left resulting in the follower facing approximately 1/8 turn to the left of the slot on Count "7". The follower shall remain in this position for Counts "7 & 8." The follower will then getting ready to swivel approximately 1/4 turn to the right by Count "1" of the next step pattern.
Count "1" of next Step Pattern: Starts with follower facing approximately 1/8 turn to the right of the slot.