Rule 8.02(c) comment
The manager or the catcher may request the plate umpire to ask
his partner for help on a half swing when the plate umpire calls
the pitch a ball, but not when the pitch is called a strike.
官方规则是有 half swing 这个名词的
但是没有详细规定怎么样叫 half swing,也没说 half swing 算不算 strike
所以垒审的时候是自由心证half swing有没有strike没错,但有half这回事也没错