If you have selected a Node, these are all the Nodes that have connected Links from your selected Node. If there are reflexive links, connecting the selected node to itself, the selected node will be included in the collection.
If you have selected a Link, the highlit part is the Node from which the Link leads. In code, this highlighting is done as follows:
// If the selected Part is a Link, cast its ToNode as a NavModelNodeData and highlight Link link = myDiagram.SelectedLink; if (link != null) { ((NavModelNodeData)link.ToNode.Data).Highlight = 1; } else { // If the selected Part is a Node, cast all the Nodes coming out of it as NavModelNodeData and highlight Node node = myDiagram.SelectedPart as Node; if (node != null) { foreach (Node other in node.NodesOutOf) ((NavModelNodeData)other.Data).Highlight = 1; } }