The back of each panel of Jerry's map tells us a lot about the history of that version of the panel. The one shown above, S4/E17, generation III, was copied from generation II on July 18, 2013. It was modified some time after that and was retired when it was copied on September 6, 2014. The copy became generation IV. Once Gen III was copied and archived it became eligible for exhibition. This sample panel has been shown five times after being retired and the museums where it has been shown are stamped on the back.
