$ cat test.csv
="12.34567890124312341234123412341234",="1-5"
$ open -a Microsoft\ Excel test.csvJUST TREAT THE NUMBERS LIKE TEXT YOU STUPID PROGRAM.
000001 === 000001 != 1
Thus, you can actually write formulas in your CSV and excel will interpret appropriately:
$ cat test.csv
=1+1,="1-5"
$ open -a Microsoft\ Excel test.csv
The documentation diverges from the excel implementation in so many places that there's a special document (which itself is incomplete): http://msdn.microsoft.com/en-us/library/dd922181(v=office.12...
"Are the rules for Excel CSV parsing written down anywhere?"
They are loosely described in ECMA-376 section 18.8.30 under the "General" format code. But like with most details surrounding XLS and XLSX, the documentation is barely coherent and incorrect in some places.