Description of Date and Time Format Standards (247873)

IMPORTANT: This article contains information about modifying the registry. Before you modify the registry, make sure to back it up and make sure that you understand how to restore the registry if a problem occurs. For information about how to back up, restore, and edit the registry, click the following article number to view the article in the Microsoft Knowledge Base:

256986 Description of the Microsoft Windows Registry

SUMMARY

This article describes the sources for the formats available on the Date and Time tabs in the Regional Settings or Regional Options tool in Control Panel.

The default date and time format options originate in the following ISO standard:

ISO 8601:1988 "Data elements and interchange formats -- Information interchange -- Representation of dates and times"

The remaining date and time formats are other typically used string values for a given region, based on linguistic research performed by Microsoft.

Microsoft has made extensive efforts to be culturally aware, and to limit the choices to options that users might actually want to use. For example, 12-hour time formats are not included as options in locales that do not use them.

MORE INFORMATION

WARNING: If you use Registry Editor incorrectly, you may cause serious problems that may require you to reinstall your operating system. Microsoft cannot guarantee that you can solve problems that result from using Registry Editor incorrectly. Use Registry Editor at your own risk.

You can override the available formats by entering your own custom values in the applicable control in the Regional Settings or Regional Options tool in Control Panel.

In Windows 95 and Windows 98, all values in the default list options are stored in the [Intl] section of of the Win.ini file. Custom values are stored under the following registry key:

HKEY_CURRENT_USER\Control Panel\International

In Windows NT and Windows 2000, all date and time format settings, whether default or custom, are stored under the following registry key:

HKEY_CURRENT_USER\Control Panel\International

For additional information, click the article number below to view the article in the Microsoft Knowledge Base:

58337 Windows 3.0 Win.ini [Intl] Section

65124 Writing International Applications for Windows

REFERENCES

For additional information about ISO standards, visit the following Web site:

http://www.iso.ch/

Microsoft provides third-party contact information to help you find technical support. This contact information may change without notice. Microsoft does not guarantee the accuracy of this third-party contact information.