How do I read a Balenciaga tag?

Balenciaga metal tags for items after 2003 use an alphanumeric code. The first line of numbers will be followed by a letter that will tell you the season and year of the bag. The brand started at Z with its Spring/Summer collection in 2005, the next season was its Fall/Winter collection, and that letter was Y and so on. For some reason, it skipped the letter X, but the rest fall predictably in place. Shop a collection of authentic Balenciaga purses from some of the world’s top boutiques on 1stDibs.