Follow these steps:
- 1. Open the System Preferences application.
2. Click International. The International pane appears.
3. Click the Date tab.
4. In the Long Date area, set the pop-up menus to this order:
Weekday
Day
Month
Year
5. Delete the comma in the field next to the Month pop-up menu.
6. Click the checkbox to enable "Leading zero for day".
7. In the Short Date area, choose Year/Month/Day from the pop-up menu.
8. Type a hyphen in the Separator field, and press Tab to update the field.
9. Click the checkboxes to enable "Leading zero for day", "Leading zero for month", and "Show century".
When you have finished these steps, your settings should look like those in Figure 1.
Figure 1 Date tab
10. Click the Time tab.
11. Click 24-Hour clock.
12. Click the checkbox to enable "Use leading zero for hour".
When you have finished these steps, your settings should look like those in Figure 2.
Figure 2 Time tab
13. Quit the System Preferences application.
Classic applications
To use ISO 8601:1988 date and time notation in Classic applications, you must also set the Mac OS 9 Date & Time control panel in the Classic environment. For steps on how to do this, see article 60752: "Mac OS 9: How to Set Date and Time to ISO 8601:1988 Standard."
More information
For more information on the ISO 8601:1988 standard, Open Sherlock and search for ISO 8601.
Note: Some applications included with Mac OS X, including Mail, may not use the date and time settings in the System Preferences application.