12c serial number oddity?

[Morgan]

I've read the explanation of the serial numbers for both the "old" style formatting and the newer formatting. I looked on the back of my 12c (purchased approx. 18 months ago) and found the serial number: CNC51207503. I know the CN refers to china, the 05 to 2005...etc. What does the second "C" refer to? I haven't been able to figure this out. All the other examples I've seen only have two letters.

[Gene]

Most I have start with CNA...

The CN is China, while I believe the 3rd letter is a plant location or some such.

I have not seen a China unit made in the last 3 years or so without a third letter.

Gene