Graphviz question - vertical then horizontal alignment

Question

Looking for help on below with Graphviz I've managed to alight subgraphs vertically (cluster0->cluster1->cluster2->etc) by using rankdir=TB and then invisible connection.

But how to order numbers within a cluster from left to right? so it would look like first row: 1 2 3 4 5 6 second row: 11 22 33 44 55 66 ...etc...

Thus top to bottom by cluster number, then left to right by node within a cluster.

Thanks in advance!

digraph G {
node [shape=box,style=filled];
newrank=True;
rankdir=TB;
splines=ortho;

1-> 11[style=invis];
11->111[style=invis];
111->1111[style=invis];
subgraph cluster_0 {
rank=same;
1
2
3
4
5
6
}
subgraph cluster_1 {
rank=same;
11
22
33
44
55
66
}
subgraph cluster_2 {
rank=same;
111
222
333
444
555
666
}
subgraph cluster_4 {
rank=same;
1111
2222
3333
4444
5555
6666
}
1->6666
}

Tried all sorts of things.

Answer 1

Using the node shape as record was the solution.

digraph G {
node [shape=record]
newrank=True;
rankdir=TB;
#splines=ortho;
ranksep=0.7;
#clusterrank=local;

D0:1-> D1:1[style=invis];
D1:1-> D2:1[style=invis];
D2:1-> D3:1[style=invis];
subgraph cluster_0 {
rank=same;
D0[label="<1>Port1|<2>Port2|<3>Port3|<4>Port4"]
}
subgraph cluster_1 {
rank=same;
D1[label="<1>Port1|<2>Port2|<3>Port3|<4>Port4"]
}
subgraph cluster_2 {
rank=same;
D2[label="<1>Port1|<2>Port2|<3>Port3|<4>Port4"]
}
subgraph cluster_4 {
rank=same;
D3[label="<1>Port1|<2>Port2|<3>Port3|<4>Port4"]
}
D0:1->D3:4
}

Result: