When a new horse race track & slots-only casino opened here a few years ago, I got some of their blank slotcards and offered to send them free to collectors. Janice asked for one, but insisted she send me some slotcards in return. She sent several and each card had a yellow post-it note on the back indicating what was different about that particular card as compared to another that might look just like it. I've still got the slotcards and her notes attached.