anchor.diff:      (:edge attribute)
       (:ranksep float)
       (:ordering (:out))
  -    (:rankdir ("LR" "RL" "BT"))
  +    (:rankdir ("LR" "RL" "BT" "TB"))
       (:dir ("forward" "none"))
       (:pagedir text)
       (:layout text) ;; neato, twopi, etc.
  
positive.code:     (:bgcolor text)
      (:url text)
      (:target text)
      (:stylesheet text)))
  
  (defparameter *node-attributes*
    '((:height float)
      (:width float)
      (: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))
      (:fontsize integer)
      (:fontname text)
      (:color text)
  
negative.code: (in-package cl-dot)
  
  (defparameter *graph-attributes*
    '((:compound boolean)
      (:label label-text)
      (:size text)
      (:page text)
      (:ratio (:fill :compress :auto)) ;; Could actually be a float number too
  