program nlces
  version 10.1


syntax varlist(numeric min=3 max=3) if,at(name)
args logoutput K L
tempname b0 rho delta
tempvar kterm lterm
scalar 'b0'='at'[1,1]
scalar 'rho'='at'[1,2]
scalar 'delta'='at'[1,3]
gen double 'kterm'='delta'*'k'^(-('rho')) 'if'
gen double 'lterm'=(1-'delta')*'L'^(-('rho')) 'if'
replace 'logoutput'='b0'-1/'rho'*ln('kterm'+'lterm') 'if'

end

这个是stata里的example，想知道at这个码有什么意义，而varlist(numeric min=3 max=3)里的min和max代表什么？怎么确定？
求高手！