# Group (i.e. subgraph) + Edge. OK.
(cluster_1:[Solar system]->{arrowhead: diamond}[Earth]){bgcolor: cornflowerblue; label: Locale} ->
# Group (i.e. subgraph) + Edge. OK.
(cluster_1:[Solar system]->{arrowhead: diamond}[Earth]){bgcolor: cornflowerblue; label: Locale} ->