digraph G {
    rankdir=LR; // Left to Right direction
    node [shape=box];

    block1 [label="1"];
    block2 [label="2"];
    block3 [label="3"];
    block4a [label="4a"];
    block4b [label="4b"];
    block5 [label="5"];
    block6 [label="7"];
    block7a [label="7a"];
    block8a [label="8a"];

subgraph cluster_foocoin {
    block7b [label="7b"];
    block8b [label="8b"];
    block9 [label="9"];
    block10 [label="10"];
    block11 [label="11"];

    labelloc = "t"
    label = "Using new rules"
}

    block1 -> block2 [dir=back];
    block2 -> block3 [dir=back];
    block3 -> {block4a,block4b} [dir=back];
    block4a -> block5 [dir=back];
    block5 -> block6 [dir=back];
    block6 -> {block7a,block7b} [dir=back];
    block7a -> block8a [dir=back];
    block7b -> block8b [dir=back];
    block8b -> block9 [dir=back];
    block9 -> block10 [dir=back];
    block10 -> block11 [dir=back];
}