digraph "Imposm Mapping" {
	graph [rankdir=LR ranksep=3]
		subgraph railway_linestring {
			node [fixed_size=shape "width:"=20]
				railway_linestring [shape=box]
				key_railway [label=railway shape=box]
					key_railway -> railway_linestring [label="rail
light_rail
subway
narrow_gauge
preserved
tram"]
		}
}