.PS
.ps 20
## figure 16
B1:	box "\xx APPL-$\alpha$"
B2:	box "\xx switch" dashed with .sw at (B1.se.x+3*linewid/2, B1.sw.y) \
		height boxht/2
B2a:	box with .s at B2.n "\xx APPL-$\beta$"
B3:	box "\xx APPL-$\gamma$"  with .sw at (B2.se.x+3*linewid/2, B1.sw.y)
##
B4:	box "ISO" "" "STACK" with .n at ((B1.s.x+B2.s.x)/2, B1.s.y-lineht) \
		height 2*boxht width 3*boxwid/2
B5:	box "TCP" "" "STACK"with .n at ((B3.s.x+B2.s.x)/2, B3.s.y-lineht) \
		height 2*boxht width 3*boxwid/2
##
B6:	box "MEDIA" "DRIVER" with .n at ((B4.s.x+B5.s.x)/2, B4.s.y-lineht) \
	width 2*boxwid
##
	line from B1.s to (B4.n.x-boxwid/6, B4.n.y)
	line from (B2.s.x-boxwid/6, B2.s.y) to (B4.n.x+boxwid/6, B4.n.y)
	line from (B2.s.x+boxwid/6, B2.s.y) to (B5.n.x-boxwid/6, B4.n.y)
	line from B3.s to (B5.n.x+boxwid/6, B5.n.y)
	line from B4.s to (B6.n.x-boxwid/6, B6.n.y)
	line from B5.s to (B6.n.x+boxwid/6, B6.n.y)
	line from B6.s to (B6.s.x, B6.s.y-2*lineht)
	line from (B1.w.x-2*linewid, B6.s.y-2*lineht) \
	     to   (B3.e.x+2*linewid, B6.s.y-2*lineht)
##
B7:	box dashed with .nw at (B1.nw.x-linewid, B2a.nw.y+lineht) \
		width B3.e.x-B1.w.x+2*linewid \
		height B2a.n.y-B6.s.y+2*lineht
##
.PE