.KF .PS boxht = boxht/1.5 arrow "user" "write" move up boxht/2 line right boxwid/2 then down boxht then left boxwid/2 move by (boxwid/2, boxht/2) spline -> right linewid then down boxht right linewid then right linewid move up boxht line up boxht/2 line right boxwid/2 move down boxht line left boxwid/2 then up boxht/2 move right boxwid/2 arrow <- "user" "write" move down boxht left linewid arrow -> right "user" "read" move down boxht/2 left linewid line left boxwid/2 then up boxht move up boxht/2 spline -> left linewid then down boxht left linewid then left linewid move up boxht/2 line down boxht then left boxwid/2 move up boxht/2 arrow left "user" "read" .PE .sp .5 .ce Figure 3. A pipe. .sp .KE