.PS 9.5i
.ps 20
## figure T-18
B1:	box "8802.3" height 3*boxht/2
B2:	box "CLNP" with .s at B1.n
B3:	box "TP4" with .s at B2.n
B4:	box "OSI TS" with .s at (B3.n.x, B3.n.y+lineht) invis
	arrow from B3.n to B4.s
C11:	box "8802.3" with .sw at (B1.se.x+2*linewid, B1.se.y) \
		height 3*boxht/2
C12:	box "CLNP" with .sw at C11.nw width 2*boxwid
C13:	box invis with .w at C11.e height 3*boxht/2
B5:	box invis with .w at (C13.e.x+2*linewid, C11.e.y) width 2*boxwid  height 3*boxht/2
B5a:	box invis with .sw at B5.sw
B5b:	box invis with .se at B5.se
B6:	box invis with .w at (B5.e.x+2*linewid, B5.e.y) height 3*boxht/2
B7:	box "CLNP" with .sw at B6.nw width 2*boxwid
B11:	box "8802.3" with .ne at B7.se height 3*boxht/2
B8:	box "CLNP" with .w at (B7.e.x+2*linewid, B7.e.y)
B12:	box "8802.3" with .n at B8.s height 3*boxht/2
B9:	box "TP4" with .s at B8.n
B10:	box "OSI TS" with .s at (B9.n.x, B9.n.y+lineht) invis
	arrow from B9.n to B10.s
##
	line from B1.s to (B1.s.x, B1.s.y-lineht) \
		       to (C11.s.x, C11.s.y-lineht) \
		       to C11.s
	line from (B11.s.x, B11.s.y) \
		       to (B11.s.x, B6.s.y-lineht) \
		       to (B12.s.x, B6.s.y-lineht) to B12.s
##
	line dashed from B3.e to B9.w
	line dashed from B2.e to C12.w
	line dashed from C12.e to B7.w
	line dashed from B7.e to B8.w
	line dashed from B1.e to C11.w
	line dashed from B11.e to B12.w
##
Z1:	box with .nw at C13.nw height 3*boxht/2 width B6.ne.x-C13.nw.x shaded
	move to (Z1.s.x, Z1.s.y-lineht/3); "NS-tunnel"
##
.PE