While it's fine and good that ISO has defined week numbers, it has been less than helpful when working with North American firms whose weeks start on Sunday and

While it's fine and good that ISO has defined week numbers, it has been less than helpful when working with North American firms whose weeks start on Sunday and who expect January 1st to be week 1. I've ended up having to write custom code to handle this in my programs as most generic libraries support ISO and not much else.