A C# interface is modeled through a Modeler Interface.
To model a C# interface in a model:
1. In the model, right-click the Model, Package or Class that is to own the interface, point to New, point to UML, point to Structure, and then click Interface.
2. Type the name of the interface.
3. Open the Interface's Property Pages, and then set the standard properties of the Interface as required.
4. If you want to specify C# specific information, such as modifiers:
a. Apply the «C# Classifier» stereotype to the Interface.