A reference to a group is created as a child of an element, group or complex type, and makes the referenced group available to its parent.
You can create a referencing group in any of the following ways:
Select the Group tool in the diagram Palette, and click on an element, group, or complex type symbol.
On the Items tab of the property sheet of a group particle, click the Add Group with Reference to Group tool (see Group particle property sheet Items tab).
For general information about creating objects, see the Objects chapter in the Core Features Guide.