How can you check a towing CSV before using its totals?

Establish what the records mean

The local lab supports UTF-8 comma-separated CSV up to 256 KB and 2,000 data rows. It expects a header, equal row widths, explicit dates and plain decimal money. Quoted commas and doubled quotation marks are supported; malformed quoting, duplicate IDs and invalid references stop calculation.

A worked example

Harmless test strings such as =1+1 or @example can be ordinary text in a source label but may be interpreted by spreadsheet software when exported carelessly. The lab neutralizes formula-like text cells with a leading apostrophe while preserving legitimate numeric amounts, including negative payment adjustments. That distinction prevents turning every negative number into unusable text.

Choose the next action

Inspect column mapping and a sample of source rows. Do not assume a file ending in .csv contains a compatible schema. Reject or isolate unexpected columns containing customer details before using a teaching tool. Keep filenames and raw contents out of logs, analytics and screenshots shared publicly.

Check whether it worked

Open the exported file and verify row counts, dates, IDs, unknowns and negative amounts. Test a malformed row intentionally with synthetic data to confirm a helpful error. Clearing the lab removes in-memory state but does not delete files already downloaded to your device. Review local file handling separately.

A repeatable review order

1. Format and size. Record the evidence and mark any missing answer as unknown.
2. Header and row-width check. Record the evidence and mark any missing answer as unknown.
3. IDs, dates and numeric rules. Record the evidence and mark any missing answer as unknown.
4. Formula-like text test. Record the evidence and mark any missing answer as unknown.
5. Reopened export verification. Record the evidence and mark any missing answer as unknown.