There is no exact or accepted definition of obsolete. To me, "obsolete" means that an item is no longer available from the original source. If we are talking about a casino table chip, then if it is no longer being used on the tables, either because the casino is closed, the tables are closed or because there is a new rack in play, then the chips are "obsolete". The catch is that with my definition, the status can change. Occasionaly, a chip that has been "obsolete" will become "live" again at the same or even a different casino. The Harrah's $1 PMSC (brass core) chips were originally used at Harrah's Lake Tahoe. They were replaced with a newer rack and became obsolete. Then they became live chips at Harrah's Reno.