My bag has a sticker on the bottom.
UK0301HI11
Going by the lot/batch code, this was made in Nov 3, 2006.
I just found this, which says DowFlake 77-80%, what we use, is being replaced by DowFlake Xtra 83-87%.
http://news.dow.com/prodbus/2006/20060717c.htm
What I get out of this is any DowFlake is good. All the new stuff made in 07 is the DowFlake Xtra.
Makes sense because I got the last bag of DowFlake at the supply store and all the new pallets were Xtra.