A gridiron pattern is a retail plan consisting of fixtures and aisles in a repeating or rectilinear pattern, best exemplified by a variety store or the food department of a standard supermarket. Secondary aisles run perpendicular to the main aisles, and each aisle is typically the same width for its length. The name "gridiron" comes from the appearance of this pattern on a diagram called a "gridiron sale slip". Before the advent of the sales counter, shoppers would place their purchases on a gridiron sale slip, which was then used by store employees to tally prices and collect debts. The pattern was also useful in preventing overstock and ensuring that items were not missed during counting. Gridiron sales slips are still used in some small stores and mainly for inventory control purposes today. They allow the manager to see at a glance how much of each item remains in stock. If an item has sold since it was last tallied, then a new slip is generated to reflect the change in status. Of course, computers can also be used for this purpose nowadays, but gridiron sales slips are still used in many small businesses because they offer another method of recording data besides simply writing it down. The pattern was first used by F.W. Woolworth Company in 1919 when they introduced the concept into the American market.