Although at first glance, you may think that
Fan can always be replaced by
Finish, this is not so. The "facing couples / ocean wave" rule applies to the Fan concept but not the Finish concept. For example, from an Eight Chain Thru formation, Fan Relay The Top is legal, whereas Finish Relay The Top is not.
EN: 65 初看时,会以为Fan 总是可以用 Finish 代替, 但其实不是这样.
"Facing couples / ocean wave" 规则适用于 Fan 概念, 但不适用于 Finish 概念.
例如, 起始队形为 Eight Chain Thru 时, Fan Relay The Top 是合乎定义的, 然而 Finish Relay The Top 是不合定义的.
CH: 65