Archie has it. Let me add from someplace small. On my Elko trips, I generally pick up common table chips, every year. And guess what, every year I find new UV marking variations on the latest rack chips.

I still believe that Paulson uses the UV marking to code the date of manufacture. I'd say that the variations are nothing more than batch markings from the chip makers.

Simple enough as the month and the year in the rotation and location. The marks are consistant within a batch of chips. For example you will find that all LEs of a run, will have the same markings in the same place.

Table chips have different markings, because they are re-ordered to replace worn chips.

As much as I have fun with UV markings, there are very few that are actually varitions or significant. The Luxor $1 is a good example.