Last number is the year. CODE will indicate the date the food was packed. Next three digits is the Julian date. On second line, first digit is plant, middle 3 is Julian day of year. The next number is year, then 24-hour time.
Date is stamped.
Proof it by bringing water to the temperature in the instructions on the back. Stir in 1 tsp. of sugar and one packet of yeast. After five minutes it should begin to bubble. At the end of 10 minutes, it should have a rounded crown of foam on it. If this happens, yeast is active.