The new 2007 Microsoft Office system file format is called Open XML Formats and applies Word, Excel, and PowerPoint.
When using the 2007 Office release, you can share your files with those using an earlier version of Office by saving your file in the 97-2003 file format.
Keyboard shortcut To open the Save As dialog box, press ALT, F, A.
A file name extension is a set of characters added to the end of a file name that determine which program should open it.
The default 2007 Microsoft Office system file format is new and is not compatible with earlier versions of Microsoft Office. For Word 2007, Excel 2007 and PowerPoint 2007, the new default extensions are .docx, .xlsx and .pptx. These new formats help:
The 2007 Microsoft Office system can open files created in earlier versions of Microsoft Office. The files are opened in Compatibility mode, and you know that you are in Compatibility mode when you see (Compatibility mode) after the file name in the title bar.
If you use Microsoft Office 2003 or earlier, and you are sent a 2007 Microsoft Office system file, you will get one of the following error messages when you try to open the file, if it is not saved in a format that is compatible.
To work with the file, you can request that the sender save the file in a format that is compatible with your version of Office. For information about saving in a compatible format, see the "Save a file for use in Office 2003 or earlier" section below.