I don't have my Nevada Gaming Commission rules with me nor the AC rules. An obsolete chip by our terms means one not only no longer in play but one a casino will not take back for value. Gene or someone can lay out the NGC rules governing the destruction of chips and Casino liability. Sometimes racks are removed but not destroyed; these "retired" chips can come back in use. I know this has been the case with some AC casinos. A retired chip, therefore, has to be considered current. Take the Binion LV Horseshoe, for example; there are old old chips still in play. The casino must honor any chip if notice of cancellation has not been given in accordance with NGC rules.