Forces the score of an element to 100, if the element's score is nonzero. Examples help clarify this.

<YesNo> ("Chloe")

If the retrieval result of the search on "Chloe" was 75, with the YesNo operator, the result would be 100; if the retrieval result is 0, it remains 0.

This operator allows you to limit a search to only those documents matching a query, without the score of that query affecting the final scores of the documents. For example, to search among documents that contain "Chloe", with "Mead" as the determinant for ranking, you cannot simply specify the following:

"Chloe" <AND> "Mead"

because that would produce documents ranked with scores combined from both elements. The following would do what you want:

<YesNo> ("Chloe") <AND> "Mead"

If the retrieval result of the search on "Chloe" was 50 and that on "Mead" was 75, without the YesNo operator, the combined result would be 50; with the operator, however, it is 75, because the score of AND is calculated to be the minimum score of all its search elements.