o<face> sub
	; o<face> call [x][y] [x][y] [ztop][zbot] [stepover_ratio]

	G90	  ; absolute x,y,z
	G90.1 ; absolute i,j,k
	M101  ; enable Z-axis (M102 disables)
	G17   ; select XY plane for arcs

	#<td> = #5410
	#<tr> = [#<td>/2]
	o1 if [EXISTS[#<_z_clearance>]]
		#<z_clearance> = #<_z_clearance>
	o1 else
		#<z_clearance> = #5
	o1 endif
	o2 if [EXISTS[#<_rampang>]]
		#<rampang> = #<_rampang>
	o2 else
		#<rampang> = 5 ; degrees
	o2 endif
	o3 if [#7 GT 0]
		#<stepover> = [#<td>*#7]
	o3 elseif [EXISTS[#<_stepover>]]
		#<stepover> = #<_stepover>
	o3 else
		#<stepover> = [#<td>*0.9]
	o3 endif

	#<minx> = #1
	#<maxx> = #3
	o11 if [#3 LT #1]
		#<minx> = #3
		#<maxx> = #1
	o11 endif

	#<miny> = #2
	#<maxy> = #4
	o12 if [#4 LT #2]
		#<miny> = #4
		#<maxy> = #2
	o12 endif

	#<cx> = [[#<minx>+#<maxx>]/2]
	#<cy> = [[#<miny>+#<maxy>]/2]
	#<rx> = [[[#<maxx>-#<minx>]-#<td>]/2]
	#<ry> = [[[#<maxy>-#<miny>]-#<td>]/2]

	#<y> = [#<miny> + #<tr>*0.8]
	#<xside> = [-1]

	G0 Z#<z_clearance>
	G0 X#<minx> Y#<y>
	G0 Z#5
	G1 Z#6

	o100 while [#<y> LT [#<maxy>]]

		G1 Y#<y>

		o101 if [#<xside> LT 0]
			G1 X#<maxx>
		o101 else
			G1 X#<minx>
		o101 endif

		#<xside> = [-#<xside>]
		#<y> = [#<y> + #<stepover>]
		
	o100 endwhile



	G0 Z#<z_clearance>


o<face> endsub