[tssva]

Trampling it to me implies that Excel was somehow modifying the contents of the file. Which it doesn't do by double clicking on the file and just viewing it. Do you mean that the data shown in Excel wasn't what was expected because of the auto data conversion?

[XlA5vEKsMISoIln]

Believe me, I was blown away just the same. And it's not like the accountant clicked a save button of a on-close dialog, no. Opening a CSV file was enough.

[tssva]

I first used Excel on Windows 3.1 and over the decades since have opened countless CSV files with it. I have never observed this behavior.