Using the Open API you can add an annotation to any base element (a model element or a symbol on the diagram pane). Annotations are used to highlight and adorn elements in the Containment tree and on the diagram pane. For example validation engine is using annotations for showing invalid elements.
Annotation has the following properties:
severity - like an error, warning, info, debug, fatal
kind - a string representing the annotation short name
text - a string representing the annotation text
target - a target base element
actions - an optional list of actions. They are shown in a diagram on a symbol’s smart manipulator.
