A data type is an instance of the DataType metaclass defined in the UML metamodel. A data type declares a type of class attribute. That type is available as a string you can include when you define attributes for other elements in a model.
For example, you can use a data type to declare a Money type. Then, you can add price : Money as an attribute to a class called Order. The UML Model Diagram template in Microsoft Office Visio includes the common data types for C++, VB, IDL, and C#, and you can add data types of your own.
Name a Data Type shape and add other property values
Open the element's UML Properties dialog box by double-clicking the icon that represents the element in the tree view or the shape that represents the element in a diagram.
Control which property values display on a shape in a diagram by right-clicking the shape, and then clicking Shape Display Options. In the UML Shape Display Options dialog box, select and clear options to display or hide property values.
Hide the operations section of a Data Type shape
Right-click the shape, click Shape Display Options, and then, under Suppress, select Operations.
Control which property values are displayed on the Data Type shape
Right-click the shape, click Shape Display Options, and then select or clear options to show or hide values.
Navigate to other views of the data type
Right-click the shape, click Views, select the view you want, and then click OK.
Show, in a view, the relationships between the data type and other elements
Right-click the shape, and then click Show Relationships.