text.mod/graphviz.mod/graphviz/tests/graphs/layers.gv

digraph G {
	layers="local:pvt:test:new:ofc";

	node1  [layer="pvt"];
	node2  [layer="all"];
	node3  [layer="pvt:ofc"];		/* pvt, test, new, and ofc */
	node2 -> node3  [layer="pvt:all"];	/* same as pvt:ofc */
	node2 -> node4 [layer=3];		/* same as test */
}