Introduction to new file-name extensions

The 2007 Microsoft Office system introduces a new file format based on XML. It is called Open XML Formats and applies to Microsoft Office Word 2007, Microsoft Office Excel 2007, and Microsoft Office PowerPoint 2007. This article describes what the new file name extensions are, how you can share the 2007 Office release files with people using earlier versions of Office, and you can learn about the benefits.

In this article

What are the new file name extensions?

Can different versions of Office share the same files?

What are the benefits of Open XML Formats?

What are the new file name extensions?

Documents, templates, worksheets, and presentations that you create in the 2007 Office release are saved with new file-name extensions with an x or an m. For example, when you save a document in Word, the file now uses the .docx extension, instead of the .doc extension.

  • The x signifies an XML file with no macros.

  • The m signifies an XML file that does contain macros.

Saving file as .docx

The following tables list the file extensions in Office Word 2007, Office Excel 2007, and Office PowerPoint 2007.


XML file type




Macro-enabled document




Macro-enabled template



XML file type




Macro-enabled workbook




Macro-enabled template


Non-XML binary workbook


Macro-enabled add-in



XML file type




Macro-enabled presentation




Macro-enabled template


Macro-enabled add-in




Macro-enabled show




Macro-enabled slide


Office theme


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Can different versions of Office share the same files?

The 2007 Office release includes both compatibility checkers and file converters to ease file-sharing between different versions of Office.

Opening previous-version files in the 2007 Office release     You can open and work on a file that was created in an earlier version of Office, and then save it in its original format. To prevent introduction of features in the 2007 Office release. The 2007 Office release uses a compatibility checker that reports those features to you and then you can remove them before continuing with the save.

Opening the 2007 Office release files in earlier versions of Office     You can open and edit a 2007 Office release file in an earlier version of Word, Excel, or PowerPoint by downloading file converters. On the computer with an earlier version of Office, go to the Download Center and download the Microsoft Office Compatibility Pack for 2007 Office Word, Excel and PowerPoint File Formats.

Important: Your version of Microsoft Office must be updated to one of the service packs in the following list. After you install the service pack for your version of Office, then download the converter.

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What are the benefits of Open XML Formats?

The Open XML Formats introduces several benefits — not only for developers and the solutions that they build, but also for individual people and organizations of all sizes:

  • Compact files     Files are automatically compressed and can be up to 75 percent smaller in some cases. The Open XML Formats uses zip-compression technology to store documents, offering potential cost savings because it reduces the disk space required to store files, and decreases the bandwidth needed to send files via e-mail, over networks, and across the Internet. When you open a file, it is automatically unzipped. When you save a file, it is automatically zipped again. You do not have to install any special zip programs to open and close files in the 2007 Office release.

  • Improved damaged-file recovery     Files are structured in a modular fashion that keeps different data components in the file separate from each other. This allows files to be opened even if a component in the file (for example, a chart or table) is damaged or corrupt.

  • Better privacy and more control over personal information     Documents can be shared confidentially, because personally-identifiable and business-sensitive information, such as author names, comments, tracked changes, and file paths can be identified and removed by using Document Inspector. For details, see Remove hidden data and personal information from Office documents.

  • Better integration and interoperability of business data     Using Open XML Formats as the data interoperability framework for the 2007 Office release set of products means that documents, worksheets, presentations, and forms can be saved in an XML format available for anyone to use and to license, royalty free. Office also supports customer-defined XML schemas that enhance the existing Office document types. This means that customers can unlock information in existing systems and use it in familiar Office programs. Information that is created by Office programs can be used by other business applications. All you need to open and edit an Office file is a zip utility and an XML editor.

  • Easier detection of documents that contain macros     Files that are saved by using the default x suffix (such as .docx, .xlsx, and .pptx) cannot contain Visual Basic for Applications (VBA) macros and XLM macros. Only files with file-name extension that end in an m (such as .docm, .xlsm, and .pptm) can contain macros.

Note: You might need to save your files in the binary file format that was used in earlier versions of Office. For example, you might be working on a document with someone who has an earlier version of Office. For this reason, the 2007 Office release still allows you to save files in previous versions.

Saving file as type

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