anchor.diff:    filename
     modified-p
     read-only-p
  -  enable-undo-p
  +  %enable-undo-p
     major-mode
     minor-modes
     head-line
  
positive.code:     (add-buffer buffer)
      buffer))
  
  (defun buffer-reset (buffer)
    (let ((line (make-line nil nil "")))
      (setf (buffer-head-line buffer) line)
  
negative.code:                                :name name
                                 :filename filename
                                 :read-only-p read-only-p
                                 :%enable-undo-p enable-undo-p
                                 :major-mode 'fundamental-mode)))
      (buffer-reset buffer)
      (setf (buffer-undo-size buffer) 0)
  