The reason food manufacturers publish dates on products is to reveal the freshness of foods or beverages. The product or manufacturing date dictates the products' usable shelf life.
Open dates reveal the expiration date of a product and are one of two main methods to show the longevity of a food product or beverage. Sometimes manufacturers stamp products with codes to show how long the products can remain for sale on store shelves.
The code should look like a code, not a date. For example, the code "13405," representing the 134th day of 2005, is a code date for a product.