The flag attribute type exposes a Y/N flag. Determination of whether the flag is set to Y or N for a particular record is carried out by checking whether the record in question is counted by an associated selection rule.
For example, suppose a selection rule – ‘Bought this year’ – is created that counts only those customers who have bought a product this year. To make life easier, you might choose to create a ‘Purchased recently’ flag attribute with a Customer target table. By associating the flag attribute with the ‘Bought this year’ rule, you create a Y/N indicator on the customer’s record that is set to Y if he or she has made a purchase this year, or N if not.