A lot of the time when people say CSV they mean “character separated values” rather than specifically “comma separated values”.

In the text files we get from clients we sometimes see tab used instead of comma, or pipe. I don't think we've seen semicolon yet, though our standard file interpreter would quietly cope¹ as long as there is nothing really odd in the header row.

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[1] it uses the heuristic “the most common non-alpha-numeric non-space non-quote character found in the header row” to detect the separator used if it isn't explicitly told what to expect