program define _3dax0
version 2.1
	mac def _n = _N
	mac def _n1 = _N + 1
	mac def _new = _N + 9 
	set obs %_new
	gen byte _Type = cond(_n>=%_n1,2,.)
	replace _x = cond(_n==%_n1,0,cond(_n==_N,1,%_1)) in %_n1/l
	replace _y = cond(_n==%_n+6,0,cond(_n==%_n+7,1,%_2)) in %_n1/l
	replace _z = cond(_n==%_n+3,1,cond(_n==%_n+4,0,%_3)) in %_n1/l
end
exit
/*
	_3dax0 x0# y0# z0#
		adds an axis meeting at (0,0,0) to the data.
		The following are observations are added to the end of the data:

				input byte _Type _x _y _z
			1	2 0 . .
			2	2 . . .
			3	2 . . 1
			4	2 . . 0
			5	2 . . .
			6	2 . 0 .
			7	2 . 1 .
			8	2 . . .
			9	2 1 . .
			end

		The misings are converted to the scaled number corresponding 
		to zero (x0# y0# z0#).
*/