.PS 5.0i
.ps 20
## figure 5
## SERVICE PRIMITIVES (cont.)
B1a:	box invis
B1b:	box invis with .n at B1a.c
B1c:	box invis with .n at B1b.s
B1d:	box invis with .n at B1c.s
B15:	box invis with .n at B1d.c
	line from B1a.nw to B15.sw; line from B1a.ne to B15.se
##
REQ:	box invis with .e at (B1b.nw.x-linewid, B1b.nw.y)
	move to REQ.e; "F-xxx.REQUEST\ " rjust
	arrow from REQ.e to B1b.nw
	arrow from B1b.nw to B1b.se dashed
IND:	box invis with .w at (B1b.se.x+linewid, B1b.se.y)
	move to IND.w; "\ F-xxx.INDICATION" ljust
	arrow from B1b.se to IND.w
RSP:	box invis with .w at (B1d.ne.x+linewid, B1d.ne.y)
	move to RSP.w; "\ F-xxx.RESPONSE" ljust
	arrow from RSP.w to B1d.ne
	arrow from B1d.ne to B1d.sw dashed
CNF:	box invis with .e at (B1d.sw.x-linewid, B1d.sw.y)
	move to CNF.e; "F-xxx.CONFIRMATION\ " rjust
	arrow from B1d.sw to CNF.e
##
.PE