Fujigen F-prefix (Japan)
1987+Length distinguishes the era. 6 digits (1987–1996): the single digit after F is the year (7=1987, 8=1988, 9=1989, 0=1990, 1=1991, …, 6=1996). 7 digits (1997+): the first two digits after F are the 2-digit year.
Gotchas & format-specific sources
- Earlier decoders assumed a 2-digit year in all F-prefix cases, producing nonsense decodes like F320327 → 2032 for a 1993 instrument. The length-branch fix is authoritative per Fujigen production records.
- F + 8 digits is not a documented Fujigen format; previously accepted here, now rejected. If you have a confirmed 8-digit F-prefix Ibanez, please open an issue with the instrument details.