| IActionableNode | A tree node whose contents is actionable. |
| ICodeNode | A special interface for nodes holding code items. |
| INode | A tree node definition, the main constituent of tree documents. |
| INodeCoordinates | A coordinates system for nodes inside an ITreeDocument. |
| ITreeDocument | A tree document is used to represent hierarchical structures. |
| IVisualNode | A visual node. |