DDR (Dynamic Document Review) The process by which Symantec Scan Engine reviews the content of the Web site before the information is passed to the user. Symantec Scan Engine scans each page and header to evaluate the information in real-time. Symantec Scan Engine compares the text on the requested site to DDR dictionaries that you have enabled. Each occurrence of a word that is contained in an active dictionary receives a numerical score. Symantec Scan Engine keeps a total score for a given amount of text. If the total score exceeds the threshold that is configured (50 is the default setting), access to the site is blocked.