.PS 6i
.ps 20
## figure 3d
B1:	box "TCP/IP-only"
B2:	box "``HYBRID''" "" "HIGHER-LEVEL ISO" "" "TCP/IP" \
		with .w at (B1.e.x+linewid, B1.e.y)
B3:	box "``DUAL''" "" "TCP/IP" "" "FULL ISO" with .n at (B1.s.x, B1.s.y-lineht)
B4:	box "ISO-only" with .w at (B3.e.x+linewid, B3.e.y)
##
	line dashed from B2.s to B4.n
##
.PE