CSV-File starts with strange HEX values

I have executed the following processing:

  • reading a CSV file (including column headers)
  • Adjust values in a column
  • Write the CSV file (including column headers)

Analyzing CSV file, i can see that it starts with HEX “EF BB BF”. Only after these three HEX values do the characters for the column headers follow.

What can this cause?

Regards,

Ray