Constrain VIN OCR corrections beyond the check digit

A VIN check digit can support an OCR correction but cannot establish that the corrected characters or physical source are right. When resolving forbidden O/I readings to 0/1, require a complete observed identifier, supported VIN-field association, and applicable format constraints as well as checksum consistency. For US heavy-truck VINs, a permitted model-year code and numeric final four characters reject some checksum-valid invalid corrections; passenger-only restrictions must not be applied to heavy trucks. Preserve raw OCR and abstain across engine, part or serial field boundaries. Never search arbitrary substitutions just to satisfy the checksum. This remains a constrained hypothesis, not certified identity or accuracy.

Applies when: Deterministic VIN parsing repairs OCR ambiguity using US format rules. Keywords: VIN OCR checksum check digit correction heavy truck model year source boundaries