Understand the output of Heinz

[CicoZhang]

graph G {
	overlap=scale
	layout=neato
	2 [label="K10213\n3.13773\n0\n2"]
	9 [label="K01488\n2.03864\n0\n9"]
	19 [label="K04765\n1.26814\n0\n19"]
	46 [label="K05851\n0.52899\n0\n46"]
	56 [label="K01510\n0.196619\n0\n56"]
	86 [label="K11751\n-0.0996626\n0\n86",shape=box]
	label="Total weight: 7.07046"
	9 -- 2
	2 -- 86
	9 -- 86
	19 -- 46
	56 -- 19
	19 -- 86
	56 -- 46
	56 -- 86
}

A minor question, what does 0 stand for in, for example, [label="K10213\n3.13773\n0\n2"]? 0 has appeared in this label.