strict digraph M {
    "Top" [shape=box,style="rounded,filled",fillcolor="/blues5/1",label=<<b>Top</b><br align="left"/>>];
    "station0" [shape=box,style="rounded,filled",fillcolor="/blues5/2",label=<<b>station0..station2</b><br align="left"/>>];
    "tankerco" [shape=box,style="rounded,filled",fillcolor="/blues5/2",label=<<b>tankerco</b><br align="left"/>>];
    "tankerco.truck0" [shape=box,style="rounded,filled",fillcolor="/blues5/3",label=<<b>truck0..truck1</b><br align="left"/>>];

    "station0" -> "tankerco" [];
}