You can base a folder or item in one application location on another folder or item stored in a different location within the same server configuration. References indicate the relationships between an original folder or item and the others based on it. References can be used to decide whether the changes you have made to a folder or item in one location need to be applied elsewhere.
Found in the lower pane of the clients, the Reference tab shows the relationships between the selected item and other folders or items with which it is associated. A folder or item may be associated with more than one project, view, or parent folder in the same server configuration because of sharing or because a child view has been created. Each instance of the original folder or item has a reference. Item references (including folders) can be viewed on the Reference tab of the lower pane. You can also view folder references from the Folder tree in the left pane by selecting from the Folder tree or context menu to display a dialog.