The NDJSON exporter validates matrix dimensions and preserves column alignment. Known Base v3 field types use their declared cell shape: array fields normalize null to [], checkboxes normalize null to false, and timestamps normalize to RFC3339. Buttons have no record value and export as null with physical type null.

Unknown field types export with manifest field_type: "not_support" and physical_type: "json". Their decoded JSON values pass through without cell normalization, including null, booleans, numbers, arrays, and nested objects. The same passthrough applies when the API explicitly returns not_support. This preserves JSON values, not original whitespace or object key order. Fallback columns report null counts without assuming a string or array shape.

The original API field types remain in the source schema so a type change between pages still fails the export, even if both types map to not_support. Malformed matrices and invalid cells of known types remain errors.