The base exception stereotype, all exception stereotypes extend from this stereotype. Allows the definition of an enumeration type. Enumerations can only contain attributes with optional default values. If the default value is not specified, the name of the attribute will be used for the enumeration value as well as the literal name. Defines the role name (if it should be different than the actual name of the actor that represents the role). Allows the object to be exposed as a value object. Value objects are those objects that will be presented to the calling client. An exception thrown an unexpected exception occurs. A reference to exception, you would use this if you did NOT want to generate the exception but instead generate a reference to an exception that you woulid then implement. Represents a exception that could occur during normal application flow. Placed on a parameter to indicate whether or not a null parameter should be allowed.