Four Kinds of Element Types are allowed:
Using the NODE keyword, the defined property will concern any Node (e.g. Box) in the diagram.
Using the EDGE keyword, the defined property will concern any Edge (e.g. Line) in the diagram.
Any Element Types defined in the UML2 metamodel can be used. For more information on Element Types, consult MDAccess for UML > Reference > API Reference.
You can access the MDAccess for UML documentation from the link
Any stereotype defined in the Model can be used.