anchor.diff:                                 :filename filename
                                  :read-only-p read-only-p
                                  :enable-undo-p enable-undo-p
  -                               :major-mode 'fundamental-mode))
  -        (line (make-line nil nil "")))
  +                               :major-mode 'fundamental-mode)))
  +    (buffer-reset buffer)
  +    (setf (buffer-undo-size buffer) 0)
  +    (setf (buffer-undo-stack buffer) nil)
  +    (setf (buffer-redo-stack buffer) nil)
  +    (setf (buffer-undo-node buffer) 0)
  +    (setf (buffer-saved-node buffer) 0)
  +    (setf (buffer-markers buffer) nil)
  +    (setf (buffer-truncate-lines buffer) t)
  +    (setf (buffer-variables buffer) (make-hash-table :test 'equal))
  +    (unless (ghost-buffer-p buffer)
  +      (push buffer *buffer-list*))
  +    buffer))
  +
  +(defun buffer-reset (buffer)
  +  (let ((line (make-line nil nil "")))
       (setf (buffer-head-line buffer) line)
       (setf (buffer-tail-line buffer) line)
       (setf (buffer-cache-line buffer) line)
  
positive.code: 
  (defun buffer-erase (buffer)
    (buffer-delete-char buffer 1 0 t)
    (let ((line (make-line nil nil "")))
      (setf (buffer-head-line buffer) line)
      (setf (buffer-tail-line buffer) line)
      (setf (buffer-cache-line buffer) line)
      (setf (buffer-cache-linum buffer) 1)
      (setf (buffer-mark-p buffer) nil)
      (setf (buffer-mark-overlay buffer) nil)
      (setf (buffer-mark-marker buffer) nil)
      (setf (buffer-keep-binfo buffer) nil)
      (setf (buffer-nlines buffer) 1)
      (setf (buffer-overlays buffer) nil)
      (dolist (marker (buffer-markers buffer))
        (setf (marker-point marker) (make-point 1 0)))))
  
  (defun buffer-check-marked (buffer)
    (cond ((buffer-mark-marker buffer) t)
  
negative.code:     (setf (buffer-mark-p buffer) nil)
      (setf (buffer-mark-overlay buffer) nil)
      (setf (buffer-mark-marker buffer) nil)
      (setf (buffer-keep-binfo buffer) nil)
      (setf (buffer-nlines buffer) 1)
      (setf (buffer-overlays buffer) nil)))
  
  (defun buffer-p (x)
    (typep x 'buffer))
  