Full syntax
recode varlist (erule) [(erule) ...] [if] [in] [, options]
where erule has the form

element [element ...] = el ["label"]

nonmissing = el ["label"]

missing = el ["label"]

else | * = el ["label"]

element has the form

el | el/el

and el is

# | min | max

for an example：recode z ... if sex==1, gen(rz) copy

看了一天不知道什么意思也没有再机器上面弄出来，很疑惑，求高手回答，I will appreciated it!