anchor.diff:      (:bgcolor text)
       (:url text)
       (:target text)
  -    (:stylesheet text)))
  +    (:stylesheet text)
  +    (:splines text)))
  +
  +(defparameter *node-shapes*
  +  '(:box :polygon :ellipse :oval
  +    :circle :point :egg :triangle
  +    :plaintext :plain :diamond :trapezium
  +    :parallelogram :house :pentagon :hexagon
  +    :septagon :octagon :doublecircle :doubleoctagon
  +    :tripleoctagon :invtriangle :invtrapezium :infhouse
  +    :Mdiamond :Msquare :Mcircle :rect
  +    :rectangle :square :star :none
  +    :underline :cylinder :note :tab
  +    :folder :box3d :component :promoter
  +    :cds :terminator :utr :primersite
  +    :restrictionsite :fivepoverhang :threepoverhang :noverhang
  +    :assembly :signature :insulator :ribosite
  +    :rnastab :proteasesite :proteinstab :rpromoter
  +    :rarrow :larrow :lpromoter :record))
   
   (defparameter *node-attributes*
  -  '((:height integer)
  +  `((:height integer)
       (:width integer)
       (:fixed-size boolean)
       (:label label-text)
  -    (:shape (:box :polygon :ellipse :oval
  -             :circle :point :egg :triangle
  -             :plaintext :plain :diamond :trapezium
  -             :parallelogram :house :pentagon :hexagon
  -             :septagon :octagon :doublecircle :doubleoctagon
  -             :tripleoctagon :invtriangle :invtrapezium :infhouse
  -             :Mdiamond :Msquare :Mcircle :rect
  -             :rectangle :square :star :none
  -             :underline :cylinder :note :tab
  -             :folder :box3d :component :promoter
  -             :cds :terminator :utr :primersite
  -             :restrictionsite :fivepoverhang :threepoverhang :noverhang
  -             :assembly :signature :insulator :ribosite
  -             :rnastab :proteasesite :proteinstab :rpromoter
  -             :rarrow :larrow :lpromoter :record))
  +    (:shape ,*node-shapes*)
       (:fontsize integer)
       (:fontname text)
       (:color text)
  
positive.code:     (:style (:filled :solid :dashed :dotted :bold :invis))
      (:layer text)
      (:url text)
      (:target text)))
  
  (defparameter *edge-attributes*
    '((:minlen integer)
      (:weight integer)
      (:arrowhead ("normal" "inv" "dot" "invdot" "odot" "invodot" "none" "tee" "empty" "invempty" "diamond" "odiamond" "ediamond" "crow" "box" "obox" "open" "halfopen" "vee" "circle"))
      (:label label-text)
      (:fontsize integer)
      (:fontname text)
  
negative.code:     (:constraint boolean)
      (:layer text)
      (:url text)
      (:target text)
      (:tooltip text)))
  