Two advanced classes of Verity operators are not used with modifiers. The score operators (YESNO, PRODUCT, SUM, and COMPLEMENT) affect how the search engine calculates scores for retrieved documents. When a score operator is used, the search engine first calculates a separate score for each search element found in a document, and then performs a mathematical operation on the individual element scores to arrive at the final score for each document. The natural language operators (FREETEXT and LIKE) enable you to specify search criteria using natural language syntax. The search engine uses natural language analysis to translate the query text into Verity query language expression for evaluating and scoring documents. The following table briefly describes each advanced operator. For examples and more detailed descriptions, see Chapter 5, "Advanced Query Language."