Google Sheets CSV export
The file produced by File → Download → Comma-separated values, or by the /export?format=csv link. People assume it is the whole workbook rendered faithfully; it is one tab, locale-formatted, with formula errors baked in.
The shape, how the file is really laid out
A CSV download captures only the active sheet, the other tabs of a
multi-tab workbook are silently omitted. Formulas are exported as their
computed values, which is helpful, but a cell showing an error exports the
error as literal text: #REF!, #N/A, #DIV/0!, #VALUE!. Numbers, dates, and
decimal separators follow the spreadsheet's locale setting, so a sheet set to
a European locale can emit "1.234,56" and day-first dates. Checkbox cells
export as TRUE/FALSE. Values Sheets auto-coerced on entry are exported in
their coerced form, an ID like "1-2" that became a date, a long account
number pushed into scientific notation, or a figure clipped to about 15
significant digits. A leading-zero code kept as text ("00734") survives only
if it was stored as text; if Sheets saw a number, the zero is already gone.
The traps
Assuming the CSV is the workbook loses every tab but the active one, and the missing tab is often the lookup table the numbers depend on.
- Every trap in this export, worked through
- The reconciliation anchor, the total the file asserts about itself
- The refusal cases, when to stop and ask instead of guess
Reference: Google Docs Editors Help, "Download · print & export files in Google Docs · Sheets · Slides" · Google Docs Editors Help, "Change your locale & language / number formats"