When you activate SingleFeed's tracking, we append tracking codes to the end of all the product URLs in your engine feeds. There are three primary tracking codes: cvsfa, cvsfe & cvsfhu.
These variables allow us to track your SingleFeed account id, the shopping engine id and the product id, respectively. These variables get appended in addition to any other tracking codes that you have setup via the SingleFeed account center. They will not affect how your listings appear at the shopping engines.