Link serial numbers to geographical area
I would like to help someone track down the individuals or families that 'dog tags' belong to. It would help tremendously if I had a clue where to look, and I understand that the first 3 or 4 digits of a serial number were assigned based on some geographical area. I would like to know more about what, if anything, I can deduce from the numbers. If there is a scheme then I hope to find some general source, as there are more than one numbers to be looked up. Any advice would be greatly appreciated.