The notecards are shown in three stacks. One contains Order cards, with attribute names and values for one order on each card. Another stack contains Product cards, written similarly. The third stack contains Order Line cards, with foreign key values from the other two plus local attribute values. The key to the exercise is to be sure that there are multiple Order Line cards that contain the same foreign key values from Orders, and Order Line cards that contain the same foreign key values from Products, but that none of the Order Line cards contain exactly the same pairing of foreign key values from the two other tables.