A reference guide for the Search Processing Language commands and syntax that you can access from the search bar. When search assistant is active it displays typeahead information as you type terms into the bar. When you type a search command into the bar, search assistant displays information for how to use the command, usage examples, a history of recent searches you built that use the command, and so on. Search assistant also includes a link to the search command's documentation.
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In the Search Manual: