(defun C:elevation-0-all-spline ( / ssnab x list-spline new-safearray- safearray- new-list )
  (load_global_variable)
  (setq ssnab (ssget "_I"))
  (if ssnab
    (progn
      
      (vla-StartUndoMark active_document)
      (setq list-spline (convert_ss_to_list ssnab))
      (foreach x list-spline
	(setq safearray-(convert-safearray-to-list-points(vlax-variant-value(vla-get-ControlPoints (vlax-ename->vla-object x)))3))
	(foreach y safearray-
	  (setq new-list (append new-list (list (list (nth 0 y)(nth 1 y) 0.0))))
	  )
	(setq new-safearray-(convert-list-points-to-polyline-safearray new-list))
	(vla-put-ControlPoints (vlax-ename->vla-object x) new-safearray-)
	)
      (vla-EndUndoMark active_document)
      )
    (princ "N")
    )
  (princ)
  )