First recorded Serial Number for each year. Guitars and Basses had their own numbering system, the only other instrument to receive it's own system was the Broadcaster.
All systems incorporate a seven-digit sequence.
While designating serial numbers to instruments, not all numbers were used. Sometimes the bridge or plate was defective and unsuitable for use. When the plates were stamped the spray filled in the numbers making them illegible. Another problem with serial numbers is the stock piling of stamped bridges and plates, causing them to be used up sporadically. Some instruments have only neck dates, which appear to have been stamped at their time of final construction, then stockpiled for later use.