digraph {
    rankdir="LR";
    dpi=300.0;
    node [shape="record"];

    table0[label="{ <data> a | <ref> }", pos="0,1!"];
    table1[label="{ <data> 5 | <ref> }", pos="1,1!"];
    table2[label="{ <data> b | <ref> }", pos="1.4,0!"];
    table3[label="{ <data> 10 | <ref> }" pos="2.4,0!"];

    edge[tailclip="false"];
    table0:ref:e -> table1:data:w;
    table1:ref:s -> table2:data:n;
    table2:ref:e -> table3:data:w;
    table3:ref:n -> table0:data:s;
}