UModelAPI - IUMLGuiAttachedNode
This GUI element is a node (possibly without a linked IUMLElement) which is directly attached to a IUMLGuiNodeLink. It disappears and pops up based on data set in the element of the IUMLGuiNodeLink it is attached to. The user usually only has control of this element via styles or the node it is attached to.
This node is used as graphical object on diagrams to represent Tagged Values for example.