• Validate assigned ISO 639-2 bibliographic and terminology language codes plus the qaa–qtz local-use range.
• Apply the same explicit rule consistently during ingest, quality control, reporting, or preservation planning.
• Expose records that need human review without silently rewriting the source data.

Twenty-one languages have distinct bibliographic and terminology codes; both forms are accepted as synonyms by ISO 639-2.^[1]

• The validator does not accept arbitrary ISO 639-3 codes and does not map a code to a language name or preferred terminology form.
• Preserve the original value and record the rule version when using this result in an archival workflow.

• Country Code ISO 3166 Alpha-2 Validator

  Use Country Code ISO 3166 Alpha-2 Validator to validate normalized values against the 249 assigned ISO 3166-1 alpha-2 country codes rather than letter-count formatting alone. Choose this tool when you need to validate assigned ISO 639-2 bibliographic and terminology language codes plus the qaa–qtz local-use range.

• ISO 8601 Date Interval Format Validator

  Use ISO 8601 Date Interval Format Validator to validate a practical ISO 8601 start/end interval subset with real Gregorian dates, clock ranges, offsets, and durations. Choose this tool when you need to validate assigned ISO 639-2 bibliographic and terminology language codes plus the qaa–qtz local-use range.