* sub-program for automatic replacement from one line to the next     
* ssa6: STB-22
program define _crctmge
	version 3.0
	local varlist "req"
	local if "opt"
	parse "`*'"
	parse "`varlist'", parse(" ")
	while "`2'"!="" {
		quietly replace `2'=`2'[_n-1] `if'
		macro shift
	}
end