dcpromo.csv

Comma-separated values Reference

A .csv file contains table data as comma-separated values. Each line is one record, and commas split the fields. The format is plain text, thus every tool can read and write it. Spreadsheets and databases import and export .csv files. Details such as separators and quoting differ between programs.

A file extension is only a part of the file name. It does not give a guarantee about the format or the content of a file. But on Windows, the extension selects the program that opens the file.