Which is why my last three employers all mandated that all employees use a format of DD/MMM/YY (so today is "11/JAN/11"). They all are US companies with significant presence outside the US, in cultures where date formats can vary. And being FDA regulated (as well as by other countries' equivalents of our FDA), it's important to have clarity of meaning on such items. Both 01/11/11 and 11/01/11 could be January 11 or November 1, depending on where you are.