Dates of the year are described in many ways in different languages. To avoid confusion in international communications, the International Organization for Standardization (ISO) adopted in 1986 an international standard (ISO 8601) for representation of dates and times. The ISO 8601 format for dates is YYYY-MM-DD, where YYYY is the year number, MM is the month (01 through 12) and DD the day number. Hyphens, not slashes, must be used as the separators in the representation (if separators are used at all; YYYYMMDD is also acceptable). Thus 2001-04-05 is the representation for the date called April 5, 2001, in traditional U.S. notation. The international standard covers numeric representations only; it doesn't prohibit traditional statements of the date, using words, in whatever the local style is. Thus "April 5, 2009" remains perfectly acceptable in U.S. usage. However, non-standard numeric representations, such as 04/05/09, should not be used, because these representations are interpreted differently in different countries. For additional information, See ISO's Date and Time Format FAQ