Greg is very close to the right answer. When the inlays are made, there is a transparency for each color. Say that the black transparency is layed down first and photographed. Then the green transparency is placed on top and photographed. Then the last color, purple transparency is place on top and photographed. A few thousand inlays may be run and they start over for the next run. The transparencies will not be placed exactly as they were on the first set. There may be differences every time that there is a new run. You may collect as many variants as you wish. Some collectors do and some don't. We feel that if we listed each and every variant, TCR would be a lot thicker. There is no change of value so why assign a new code and list them?