Starting in 1977, Gibson adopted the current date-based serial system which codes for the year and day of production. The first number of the sequence indicates the decade of production, followed by the three digit day of the year, and finally the year. For example, the serial number 90237XXX corresponds to a production date of 1/23/97. The last three (or four as of 2005) digits signify the location of production and batch number, respectively, but this information isn’t necessary to.