This policy setting determines the state of the user option, "Save date and time values using ISO 8601 date format". This ...

This policy setting determines the state of the user option, "Save date and time values using ISO 8601 date format". This option enforces the use of ISO 8601 date formats when saving Excel files, which may limit Excel's ability to interoperate with other spreadsheet applications or with earlier versions of Excel.

If you enable the policy setting, the user option will be set.

If you disable the policy setting, the user option will not be set.

If you do not configure the policy setting, the user option will not be set by default.