Season Pass Renewal by mail

Hey, I was just reading the Season pass renewal form that I printed off the Cedar Point website and it says to send the renewal form in along with the season pass certificate. My question is what is the "season pass certificate", is it my season pass from last year or something else? Thanks for your help

Its the certificate they give you when you purchase a pass online or from the season pass office (before processing)
. You will have to purchase and receive a 2002 Season Pass certificate before you can renew by mail.