Positions 1–3 (WMI) identify the manufacturer and assembly region. JT4/JT5 are Japan-built; 4TA/4TE are NUMMI Fremont; 5TE/5TF/5TG are San Antonio or Tijuana.
Position 10 is model year. Position 11 is the plant. Position 9 is the check digit — the Codex verifies it with the standard NHTSA weighted-sum formula.
Positions 4–8 encode body, engine, cab, and drivetrain, but Toyota's VDS mappings vary by year and aren't fully published. The Codex shows you every catalog entry consistent with the decoded year and generation rather than guess at specifics the VIN cannot guarantee.