Which node is specifically designed to illustrate UI elements for extension nodes?

The Ext Demo node is specifically designed to showcase user interface (UI) elements for extension nodes within SAS Enterprise Miner. This node serves as a template or example that allows users to see how their custom nodes can interact with the application and how they can be presented in the interface. It is particularly useful for developers working on creating their own extension nodes, as it provides visual demonstrations of various UI components, such as controls, input fields, and output displays, that can be incorporated into these custom nodes.

By utilizing the Ext Demo node, users can gain insights into the design and functionality of nodes they might develop, ensuring a better integration and user experience when interacting with their custom solutions. This emphasizes the importance of the node in the context of extending SAS Enterprise Miner, as it not only serves educational purposes but also aids in the actual development process. Other nodes in the list do not serve this specific purpose related to UI elements for extension nodes.