Citat din
http://support.microsoft.com/kb/214058:
When the date system in Microsoft Excel was originally created, it was designed to be fully compatible with date systems used by other spreadsheet programs.
However, in this date system, the year 1900 is incorrectly interpreted as a leap year. Because there is no February 29 ("leap day") in the year 1900, the day of the week for any date before March 1, 1900 (the day after the "leap day"), is not computed correctly.
Vezi şi
http://support.microsoft.com/kb/205719:
In the Microsoft Office Spreadsheet Component, the value 0 evaluates to the date December 30, 1899 and the value 1 evaluates to December 31, 1899. This is different from Microsoft Excel. In Excel, the value 0 evaluates to January 0, 1900 and the value 1 evaluates to January 1, 1900. The date January 0, 1900 does not exist in the Microsoft Office Spreadsheet Component.
In addition, the Office Spreadsheet Component does not recognize the year 1900 as a leap year. After March 1, 1900, however, dates in the Microsoft Office Spreadsheet Component and Microsoft Excel begin to match.
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