Good catch on the re-list. Here is another couple of pennants that the original seller states came from the same group of sewn "showroom" pennants.
http://www.ebay.com/itm/Camden-NY-an...p2047675.l2557
Not sure that it proves anything one way or the other as to what ABC stands for, but for anyone looking to sink big bucks into this one, I think it would be worth discussing where they came from with the original seller.