Query filters
From OpenSearchServer Wiki
The goal of this function is to apply further query parameters to refine a search result. In the screen capture above, everything that is not in Danish is being filtered out.
Simply type a standard OSS query, which will be applied to the current search results. See this page for the OSS querying language.
Making queries at this stage has the advantage of working on a smaller data set - the current search results rather than the whole body of data in the index. OSS-illiterate users can of course be provided with buttons, menus and the like that actually execute a standard query through the OSS APIs.
