Try a CSV with issues you can trace
name,postal_code,postal_code,note Ada,00123,02108,ready Lin,90210,10001,=2+2 Sam,60601
In the converter, choose Use sample, then Validate and preview. Expect 3 data rows and 4 columns, with a duplicate-header warning, a short source row 4, two leading-zero values, and one formula-like cell. Review these findings before downloading a report or normalized CSV.
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