*! version 1.0.0  1/20/93  STB-12: gr12
program define _ggroup
	version 3.0
	local type "`1'"
	mac shift 
	local g "`1'"
	mac shift 
	mac shift				/* discard = sign */
	local varlist "req ex"
	local in "opt"
	local if "opt" 
	local options "Missing"
	parse "`*'"
	tempvar touse
	quietly { 
		gen byte `touse'=1 `if' `in'
		if "`missing'"=="" {
			parse "`varlist'", parse(" ")
			while "`1'"!="" {
				local t : type `1'
				if substr("`t'",1,3)=="str" {
					replace `touse'=. if `1'==""
				}
				else	replace `touse'=. if `1'==.
				mac shift
			}
		}
		sort `touse' `varlist'
		quietly by `touse' `varlist': /*
			*/ gen `type' `g'=1 if _n==1 & `touse'==1
		replace `g'=sum(`g')
		replace `g'=. if `touse'!=1
		sort `g'
	}
	label var `g' "group(`varlist')"
end