1.PS 2 Lpd: box "lpd" 3 Filter: box "Filter" with .w at Lpd.e + (.5,0) ; 4 Printer: box "Printer" with .w at Filter.e + (.5,0) ; 5 arrow <-> from Lpd.e to Filter.w; 6 arrow <-> from Filter.e to Printer.w; 7.PE 8