://(Note that the sidebar tabs will be hidden by the search results until you click the 'x' to the right of the search box to delete the search results)//
To the right of the search box, when there are no search results displayed below it, you will find an ellipsis (...). Clicking on the ellipsis will open $:/AdvancedSearch. This tiddler contains four tabs.
*The ''standard'' tab contains another instance of the search box found in the sidebar.
*The ''system'' tab allows you to limit your search to system tiddlers.
*The ''shadows'' tab allows you to limit your search to shadow tiddlers.
*The ''filter'' tab is not a search box, per se, but a way to obtain a list of all tiddlers that meet the specific criteria described by that filter, for example, "All tags except system tags".