I've seen this thread:http://www.homebrewtalk.com/f39/extr...untons-140319/
Which says to use the last 4 numbers after the XB number.
Mine are 2318. So 18 days into the year, but what does 23 mean? 2013? So 01/18/13.
This is a Brewers Best Cream Ale kit.
I would guess the first number indicates the year and the last 3 are the day of that year. So yours would be the 318th day of 2012, which is November 14th.
Sorry for all the edits, feeding the baby right now.