Do not silently interpret parenthesized values as negative numbers

Parentheses do not have one universal meaning

Confirm what the source means before converting the value so the spreadsheet does not turn an assumption into a calculation.

Test an invoice with the dates, quantities or amounts you find hardest to copy accurately. ParseMill puts extracted invoice fields beside the source for review and correction before export. Open the downloaded workbook in your usual spreadsheet application and check those values there too.

Retain the complete string and inspect the source heading, legend and surrounding notation. Record the convention only for the field or section where it is established. A familiar appearance is a reason to investigate, not evidence of the correct interpretation.

Compare these synthetic cases

Each row is an invented example of a different context. The uncertainty-like string is deliberately unresolved. This worksheet does not claim that every trailing parenthesis has a particular scientific meaning or that an estimate should be treated as an ordinary unqualified observation.

NIST: Basic uncertainty definitions explains that uncertainty is associated with measurement results. If parentheses refer to uncertainty, preserve the relevant definition rather than forcing the notation into a negative-number rule.

Make the conversion decision reviewable

1. Capture the raw string, field name and source location before changing its type. Check whether parentheses are printed in the source or introduced by spreadsheet formatting.
2. Find an explicit convention in the report or its governing documentation. Save the evidence and its applicable range.
3. Create a separate interpreted value only when the convention is confirmed. Add an interpretation label such as negative amount or estimated result.
4. Test both parenthesized and unparenthesized examples from the same range. Keep unresolved cases out of automatic scalar conversion.

Microsoft: Table.TransformColumnTypes changes column types using stated conversions. Type conversion is a mechanical step after a notation decision; it does not establish what the parentheses meant in the source.

Handle display and data separately

A spreadsheet may display an existing negative number with parentheses even when the imported text had a minus sign. That display choice should not be confused with source transcription. Keep a raw-text field if the exact reported notation matters to review.

If parentheses were stripped earlier, return to the original document to recover them. Do not infer their original location from the current numeric sign. They may have enclosed only an annotation or uncertainty term rather than the complete value.

Use an explicit unresolved outcome

For the fixture, only the first row has evidence supporting a negative conversion. The other rows preserve their distinct roles, and the uncertainty-like expression awaits clarification. Record this result in the handoff so a later user does not repeat the same unsupported conversion.

Try an invoice with a parenthesized amount and a description containing ordinary parentheses. Compare both with the source and inspect any unresolved value before export. Use the non-accounting examples above as separate review criteria for a broader document assessment.