program def safedrop
*! NJC 1.1.0 11 February 2003
*! NJC 1.0.0 13 November 2000
	version 8.0
	foreach v of local 0 {
		unab V : `v'
		if "`V'" == "`v'" {
			local OKlist "`OKlist'`v' "
		}
		else local badlist "`badlist'`v' "
	}

	local nb : word count `badlist'
	if `nb' {
		local names = plural(`nb',"name")
		di "{p}{txt}incomplete variable `names': {res}`badlist'{p_end}"
		exit 198
	}
	else drop `OKlist'
end