The node's name in the DOT source, which edges name it by.
What the drawing says on the node: its <text> elements, in drawing
order, joined by spaces. Empty for a node drawn with no text, such as
shape=point.
The clusters the node is drawn inside, by their labels, outermost first. Empty for a node outside every cluster.
The node's group.
One node Graphviz drew: a
<g class="node">.