anchor.diff:  It only changes when deleted.")
      (owners (make-hash-table)
              :type hash-table
  -           :documentation "The key is an owner, the value is an `owner-header'.")
  -   (current-owner-header nil
  -                         :type t
  -                         :documentation "Must be one of the `owners' values."))
  +           :documentation "The key is an owner identifier (an artitrary balue),
  +the value is an `owner'.")
  +   (current-owner nil
  +                  :type t
  +                  :documentation "Must be one of the `owners' values."))
     (:export-class-name-p t)
     (:export-accessor-names-p t)
     (:accessor-name-transformer #'class*:name-identity)
  
positive.code:    (children '()
               :documentation "List of nodes.")
     (bindings (make-hash-table)
               :documentation "The key is an owner, the value is a
  `binding'.  This slot also allows us to know to which owner a node belongs.")
     (data nil
           :type t
  
negative.code:             :documentation "The owner in `origin's parent node that created this owner.
  Unless the parent was disowned by this `creator',
  
    (gethash CREATOR (bindings (origin OWNER)))
  
  should return non-nil.")
     (current nil
  