Unix seconds versus milliseconds
The same digits can describe different instants when their units change.
Choose the unit first
Unix time starts at 1970-01-01T00:00:00Z. Seconds 0 is that instant. Seconds −1 is 1969-12-31T23:59:59Z. Milliseconds divide each second into a thousand parts.
Use explicit ISO timestamps
An ISO timestamp with Z or a numeric offset identifies an instant. An ISO local timestamp without an offset also needs a named zone and any DST decision. Ambiguous slash dates are rejected.
Keep bad rows visible
In Batch Time Lab, choose the representation and column yourself. Blank or invalid cells stay in order with errors. The valid-row total excludes them, and exports retain their row identity.
Published by TrueHour · Calculation rules, sources and limitations · Report a correction