anchor.diff:  
   (defclass standard-graph-output-record (graph-output-record
                                           standard-sequence-output-record)
  -  ((orientation
  -    :initarg :orientation
  -    :initform :horizontal)
  -   (center-nodes
  -    :initarg :center-nodes
  -    :initform nil)
  -   (cutoff-depth
  -    :initarg :cutoff-depth
  -    :initform nil)
  -   (merge-duplicates
  -    :initarg :merge-duplicates
  -    :initform nil)
  -   (generation-separation
  -    :initarg :generation-separation
  -    :initform '(4 :character))
  -   (within-generation-separation
  -    :initarg :within-generation-separation
  -    :initform '(1/2 :line))
  -   (hash-table
  -    :initarg :hash-table
  -    :initform nil)
  -   (root-nodes
  -    :accessor graph-root-nodes) ))
  +     ((orientation
  +       :initarg :orientation
  +       :initform :horizontal)
  +      (center-nodes
  +       :initarg :center-nodes
  +       :initform nil)
  +      (cutoff-depth
  +       :initarg :cutoff-depth
  +       :initform nil)
  +      (merge-duplicates
  +       :initarg :merge-duplicates
  +       :initform nil)
  +      (generation-separation
  +       :initarg :generation-separation
  +       :initform '(4 :character))
  +      (within-generation-separation
  +       :initarg :within-generation-separation
  +       :initform '(1/2 :line))
  +      ;; removed HASH-TABLE slot and stuffed it into
  +      ;; GENERATE-GRAPH-NODES method definition [2005/07/25:rpg]
  +      (root-nodes
  +       :accessor graph-root-nodes)
  +      ))
   
   (defclass tree-graph-output-record (standard-graph-output-record)
  -  ())
  +     ())
  +
  +;;;(defmethod initialize-instance :after ((obj tree-graph-output-record) &key merge-duplicates)
  +;;;  (when merge-duplicates
  +;;;    (warn "Cannot use a TREE layout for graphs while merging duplicates.")))
   
   (defclass dag-graph-output-record (standard-graph-output-record)
  -  ())
  +  (
  +   ))
   
   (defclass digraph-graph-output-record (standard-graph-output-record)
     ())
  
positive.code:                                (incf v within-generation-separation)))
                             (graph-root-nodes graph-output-record)))))))))))
  
  #+ignore
  (defmethod layout-graph-edges ((graph-output-record standard-graph-output-record)
                                 stream arc-drawer arc-drawing-options)
  
negative.code:                     #'cont
                      (find-graph-type graph-type)
  		    nil
  		    ;; moved to local variable... [2005/07/25:rpg]
                      ;; :hash-table (make-hash-table :test duplicate-test)
  		    graph-options 
  		    ))))
        (setf (output-record-position graph-output-record)
              (values cursor-old-x cursor-old-y))
        (with-output-recording-options (stream :draw t :record nil)
  