strict digraph M {
    subgraph "cluster_Top" {
        label=<<b>Top</b>>
        style="filled"
        fillcolor="/blues5/1"
        "Top" [shape=box,style="dotted,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"/>
            <br/>
            <i>_monitor_reservoir</i><br align="left"/>
            <i>_traffic_generator</i><br align="left"/>>];
        subgraph "cluster_tankerco" {
            label=<<b>tankerco</b>>
            style="filled"
            fillcolor="/blues5/2"
            "tankerco" [shape=box,style="dotted,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"/>
                <br/>
                <i>_dispatch_loop</i><br align="left"/>>];
        }
    }

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