digraph OL {
    fontname=arial;
    style=filled;
    node [fontname=arial, shape=box, style=filled, color=grey80];
    edge [fontname=arial, fontsize=10, dir=both];
    
    subgraph cluster0 {
        color=grey90;
        POE [ label="POE" ];
        Wheels -> POE -> Selects;
    }
    OL1 [ label="Object layer\n(Addressing | Routing | Monitoring)" ];
    OL2 [ label="Other object layer\n(Addressing | Routing | Monitoring)" ];


    IKC [ label="IKC\n(Addressing | Routing | Monitoring)"];
    ROUTE2 [ label="Stem-compatibility\n(Addressing | Routing | Monitoring)"];
    
    POE2 [ label="Remote kernel"];

    OL2 -> POE;
    OL1 -> POE;
    POE -> IKC -> POE2;
    POE -> ROUTE2 -> Stem ;

}