digraph G { rankdir=LR; edge [color=blue]; subgraph cluster0 { legend_attribute [label="Attribute"]; legend_attribute2 [label="Attribute"]; legend_attribute3 [label="Attribute"]; legend_class [shape="box", label="Class"]; legend_rule [shape="diamond", label="Rule"]; legend_class -> legend_rule; edge [color="black"]; legend_class -> legend_attribute [label="Required"]; edge [color="gray"]; legend_class -> legend_attribute2 [label="Optional"]; edge [color="green"]; legend_class -> legend_attribute3 [label="Choice"]; labelloc="t"; label="Legend"; } labelloc="t"; fontsize=32; label=" v"; } [shape=box]; ; "" [shape=diamond]; /* Associations from */ edge [color=green]; -> ; edge [color=black]; edge [color=gray]; -> ; edge [color=black]; : /* Rules for */ / / : "" -> ;