anchor.diff:    (iterate-elements
      (data data-set)
      (lambda (datum)
  -     (format out "~{~A ~}~C" datum #\Linefeed)))
  +     (format out "~{~S ~}~C" datum #\Linefeed))) ; gnuplot wants strings/labels/... quoted
     (format out "e~C" #\Linefeed))
   
   (defmethod make-plot ((plot-kind symbol) data 
  
positive.code: 
  (defmethod make-data-point ((point-kind (eql :box)) datum
                              &key (x-coord 'first) (y-coord 'second) (width 0.5)
                              (offset nil)
                              &allow-other-keys)
    (append 
  
negative.code:            (if first?
               (format out "plot")
               (format out ","))
  	   (if (labelsp plot)
  	       (format out " '-' using 1:2:3:xticlabels(4) with ~A " (style data-set))
  	       (format out " '-' with ~A " (style data-set)))
             (write-plot-settings data-set out)
             (setf first? nil)
             (incf index))))
  