property Node.Image as Long
Retrieves or sets a value that indicates the index of icon to display in the node.

TypeDescription
Long A long value that indicates the index of the icon in Images collection. The Images collection is 1 based.
Use the Image property to assign an icon to a node. The node's icon is displayed on the left side of the node. The node's picture is displayed on the child level area. Use the Picture property to assign a picture to a node. Use the Images method to load icons to the control.

In case you are using the LoadXML method, the Image property of the Node indicates the type of XML node being added. The type of valid XML nodes are:

Use the Images method to add images to the control, so each type of element in your XML file, has a specific representation. The first icon in the Images collection indicates the NODE_ELEMENT type, the second icon in the Images collection indicates the NODE_ATTRIBUTE type, and so on.