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