I’m just getting into Google Merchant Center and I’m Figuring it out but I’m stuck on UPCs. We sell comic books which have a sort of extended UPC where the extended (5 digits) denotes issue number, variant cover and printing (1st, 2nd, etc.). Google does not recognize these as valid numbers. If I chop off the “extra” five digits, what the numbers represent are a publisher and series (DC Comics Batman 2011 series for instance). Comics before the mid 1970s didn’t have any number at all. So, how can I deal with this? When I post our 150,000 items, the majority of them are flagged for not having valid numbers or no number at all. I have tried searching Google just using UPCs (both with and without the five digits) and got lots of results but none of them were even comic books. Any ideas?