From the Club 100 support files (www.club100.org)...

SERIAL NUMBER SECRETS

Every Model 100, 102 and 200 has a serial number. Here is the secret meaning to that number:

The first digit is the last digit of the year of manufacture (198x).

The next two digits are the month of manufacture.

The rest of the digits are an incremental count of assembly line passage.

This explanation comes from Roger Merchberger, the keeper of the Club 100 discussion line.