Opening old workbooks in Excel 2002

From Microsoft Exel 2002 Help
Using Excel 2002 files with earlier versions of Excel
Opening old workbooks in Excel 2002

Change the default file format By default, Excel saves workbooks in the most recent file format, which was introduced with Excel 97. If others you work with use an earlier version of Excel or another spreadsheet program, you can change the default file format that Excel 2002 uses when saving workbooks. For example, if many people in your company use Excel version 5.0, you can save your Excel 2002 workbooks in Microsoft Excel 5.0/95 Workbook format. All workbooks will be saved in this format unless you specify a different file format in the Save As dialog box (File menu).

Use the dual file format If an earlier version of Excel is still widely used in your workplace, and you want to continue to use Excel 2002 format but still share your workbook with others, you can save your Microsoft Excel 2002 workbooks in a special dual file format.

What is the dual file format? The workbook is saved in a single file that includes Excel 97-2000 and Excel 5.0/97 file formats. Users of Excel 2002 can continue to work in a workbook saved in the dual format without losing any features or formatting unique to this version. When users of Excel 95 open the workbook, a message is displayed that recommends they use the file read-only. However, if users ignore the recommendation and save the workbook in a format other than the dual file format, features and formatting that are available only in later versions of Excel are lost.
Protect your work To avoid losing work created in the latest version of Excel, you can protect a workbook from changes by requiring a password to change the workbook or by making the workbook read-only.
You can save specific workbooks in the dual file format by using the Save As command on the File menu, or you can specify the dual file format as the default file format for saving all of your workbooks. Workbooks saved in the dual file format are larger than those saved in a single format.