<http://schema.org/about>
"It\u2019s important to know when companies use an actual expiration date on items or a sell-by date. Often, the date printed on the package is the sell-by date, so"^^<http://www.w3.org/2001/XMLSchema#string>
<http://www.mnn.com/food/healthy-eating/questions/how-accurate-are-food-expiration-dates>