Control position of clusters in Graphviz - graphviz

Question

I have a graphiz project where I would like to position my clusters horizontally from left to right with cluster_c2 (called QGIS) in the middle. I have attempted to use the newrank=true; as described here without success. The current output of my graphviz script is:
My current script is:
digraph {
node [shape=record, fontname="Arial"];
rankdir=LR;
L [label="Line"]
ML [label="Multi-Line"]
QL [label="Line"]
QML [label = "Multi-Line"]
QCS [label = "Circular-String"]
QCC [label = "Compound-Curve"]
P [label="PolyLine"]
subgraph cluster_c1 {
label = "SpatiaLite";
fontname="Arial";
L;
ML;
}
subgraph cluster_c2 {
label = "QGIS";
fontname="Arial";
QL;
QML;
QCS;
QCC;
}
subgraph cluster_c3 {
label = "Shapefile";
fontname="Arial";
P;
}
L -> QL [dir=both];
QCS -> L [color=grey];
QCS -> ML [color=grey];
QCC -> ML [color=grey];
QML -> ML [dir=both];
QCC -> L [ color=grey];
QML-> L [color=grey];
QL -> ML [color=grey];
QCS -> P;
QCC -> P;
QML -> P [dir=both];
QL -> P ;
}

Answer 1

I don't know how it works, but it seems that combination of newrank="true" and rank=same inside each subgraph works:
digraph {
node [shape=record, fontname="Arial"];
newrank=true;
rankdir=LR;
L [label="Line"];
ML [label="Multi-Line"];
QL [label="Line"];
QML [label = "Multi-Line"];
QCS [label = "Circular-String"];
QCC [label = "Compound-Curve"];
P [label="PolyLine"];
subgraph cluster_c1 {
rank=same;
label = "SpatiaLite";
fontname="Arial";
L;
ML;
}
subgraph cluster_c2 {
rank=same;
label = "QGIS";
fontname="Arial";
QL;
QML;
QCS;
QCC;
}
subgraph cluster_c3 {
rank=same;
label = "Shapefile";
fontname="Arial";
P;
}
L -> QL [dir=both];
ML -> QML [dir=both];
QCS -> L [color=grey];
QCS -> ML [color=grey];
QCC -> ML [color=grey];
QCC -> L [ color=grey];
QML-> L [color=grey];
QL -> ML [color=grey];
QCS -> P;
QCC -> P;
QML -> P [dir=both];
QL -> P ;
}