I am not one of the more experienced here so I am sure someone will give you a more definitive definition. I don't know the status of the Flamingo Hilton chips. Have they ever been the subject of a recall or "Notice of Redemption". My understanding or definition would be if the casino has issued a notice that they are redeeming the chips and that redemption has expired, than the chips would be considered Obsolete. Otherwise, if they are still redeemable at the cage they wouldn't be "Obsolete"

Would that be a correct definition?

I know there are other casinos out there that issue new editions of chips all the time but don't recall the previous. I have gone places where you find different variations at the tables all the time. As long as the basic designs remain the same, I don't know what confusion would be for the dealer. Some, that I have seen, for example all use the same basic chip. Same colors, Same spots or stripes etc. The center designs only change. SO, in a rack you can't tell one chip from another. Note some places with a lot of LEs or Commemoratives. The Orleans, Tropicana, Four Queens, I think, all come to mind. While center designs may vary, the edges are all the same and easilly destinguishable from one denomination or antother etc.

I mention The Orleans. It has been some time since they put a LE or commemorative that I know of. However, when playing, I do frequently pick up Poker Tournements 1 2 3 or 4 chips along with CCGTCC convention and y2k and an occasional Grand Opening. They also have 1996 2005 and now 2006 chips in addition to possibly others. While there are variations or stark differences in the centers, the edges and basic chip is all the same.