This is particularly funny because I just received a ticket saying that the CSV import in our product doesn't work. I asked for the CSV, and it uses a semicolon as a delimiter. That's just what their Excel produced, apparently. I'm taking their word for it because... Excel.

To me, CSV is one of the best examples of why Postel's Law is scary. Being a liberal recipient means your work never ends because senders will always find fun new ideas for interpreting the format creatively and keeping you on your toes.