ISO 8601:2004 is applicable whenever representation of dates in the Gregorian calendar, times in the 24-hour timekeeping system, time intervals and recurring time intervals or of the formats of these representations are included in information interchange. It includes

• calendar dates expressed in terms of calendar year, calendar month and calendar day of the month;
• ordinal dates expressed in terms of calendar year and calendar day of the year;
• week dates expressed in terms of calendar year, calendar week number and calendar day of the week;
• local time based upon the 24-hour timekeeping system;
• Coordinated Universal Time of day;
• local time and the difference from Coordinated Universal Time;
• combination of date and time of day;
• time intervals;
• recurring time intervals.

ISO 8601:2004 does not cover dates and times where words are used in the representation and dates and times where characters are not used in the representation.

ISO 8601:2004 does not assign any particular meaning or interpretation to any data element that uses representations in accordance with ISO 8601:2004. Such meaning will be determined by the context of the application.