If you'd put the year after it it would be really day-month-year (like we do it in Germany) but with only month and day (or day and month) it is always hard to guess. Also the sorting month-year is much more logical for a computer as it will sort them in the right order (all files from july after the files from june) with day-month it shows all files from all month's first, then the ones from all month's seconds, and so on. So logical for files is yyyymmdd and not ddmmyyyy.