Deriving by Union

You can derive an element or simple type by union to define it as a collection of built-in and simple data types.

1. Open the property sheet of an element or simple type, and select Union in the Derivation list.

   For elements, the Embedded type field is set to Simple.

2. Click the Properties tool to the right of the Derivation box to open the union property sheet and complete the following properties:

   Property	Description
   ID	ID of the simple type union. Its value must be of type ID and unique within the model containing the simple type union.
   Member Types	White space separated list of built-in data types. Values must be qualified names.

3. [optional] Click the Union Types tab and add appropriate simple types to the union.
4. Click OK to close the union property sheet and return to the element or simple type.