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Index Groups 
If you have a large number of indexes at your disposal, use index groups to group indexes together according to content criteria.
This provides more clarity in the Search Options dialog box: You can switch complete index groups on or off. Indexes that are not assigned to an index group are displayed in the search options under Miscellaneous.
When you create an index, you can select a group. You can change the assignment at any time in the index properties.
To create an index group, in the input field next to the Group selection field, enter a name for the index group, and choose Add. The new index group now appears in the selection field. Save your settings.
In the Group selection field, choose the –Select- entry. This cancels the existing assignment to an index group. Save your changes.