digraph G {
  graph [URL="default.html", BGURL="background.gif"]
  node [URL="\N.html", style=filled]

  // edge URLs are not supported by imagemap clients, but they are allowed.
  edge [URL="\N.html"] 
 
  hi [color=red]
  medium [color=yellow]
  lo [color=green]
 
  hi->medium->lo
  hi->lo
}
