(defun c:3du()
(princ "\nSelect 3D Polylines:")
(setq lset(ssget (list (cons 0 "POLYLINE"))))
(setq adVal(getreal "\nType the value to be added :"))
(if (= lset nil)
(progn
(princ "\nNothing Selected")
)
(progn
(setq llen(sslength lset))
(setq lcntr 0)
(repeat llen
(setq curl(ssname lset lcntr))
(setq vt (entnext curl))
(while (/= (cdr (assoc 0 (entget vt))) "SEQEND")
(setq ed (entget vt))
(setq old (assoc 10 ed))
(setq 3dp(cdr old))
(setq nlistx(car 3dp))
(setq nlisty(cadr 3dp))
(setq nlistz(+ adVal (caddr 3dp)))
(setq new (cons 10 (list nlistx nlisty nlistz)))
(setq ed (subst new old ed))
(entmod ed)
(setq vt (entnext vt))
)
(entupd curl)
(setq lcntr(1+ lcntr))
)
)
)
(princ)
)
(princ "\nType \"3du\" to update ZValue of Verticies of 3DPolyline") (princ)