Here are links to two past threads on this subject.

This link was to a post by Pete Porro, listing the various known combinations (at that time).

http://www.thechipboard.com/cgi-bin/tcbarc10/tcbarc10.pl?read=296777

This link is to a post I made following the
2003 Convention. I was passing along information from one of the Educational Seminar guests, who was a representative of Chipco. He stated that mixed codes were not by design. They are errors, but fairly common ones.

http://www.thechipboard.com/cgi-bin/tcbarc08/tcbarc08.pl?read=225612

I was not aware that current re-orders are sans any codes. As I recall my conversation with the Chipco reppresentative, he said that it was Chipco, not the Luxor, that decided to put the UV markings on the chips. Perhaps they (Chipco) have decided to stop doing it.

Jim Follis