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Office Open XML I: Exploring the Office Open XML Formats

Office Open XML Formats in Word, Excel, and PowerPoint

Macro-free and macro-enabled Office Open XML Formats are available for both documents and templates in Word, Excel, and PowerPoint, as well as for PowerPoint shows.

The file extensions for the Office Open XML Formats use four characters. Most of these file extensions start with the three-character extensions you know from earlier versions, such as .doc and .xls, and then add a fourth character (in most cases, either the letter x or the letter m) at the end.

  • The letter x at the end of a file extension (such as .docx or .xlsx) means that macros cannot be stored in the file.
  • The letter m at the end of a file extension (such as .docm or .xlsm) indicates that you can store macros in the file.

Several file types, such as documents and templates, are available in both macro-enabled and macro-free formats.

Note     Macro-free files are an easy way to help protect both your security and the privacy of your proprietary content. For example, when you finish a document that contains a set of custom macros, you may want to save a macro-free copy of that document to share with others. However, when you want to save macros in your document, be sure to change the Save as type option to a macro-enabled format when saving the file.

Default file format

To help protect your computer from malicious macros, macro-free formats are the default file formats for Word, Excel, and PowerPoint. That is, .docx for a Word document, .xlsx for an Excel workbook, and .pptx for a PowerPoint presentation. To change the default file format for new documents that you save in any of the referenced programs, do the following:

  1. In Word, Excel, or PowerPoint, click the Microsoft Office Button Button image and then click <Program> Options, which you'll find at the bottom of the menu.
  2. In the dialog box that opens, click the Save tab.
  3. Select the file type you want to use as a default from the list labeled Save files in this format.

Several document, template, and Web-based file types are available as the default formats for Word and Excel. For PowerPoint, the default must be a presentation format, but you can select from macro-free or macro-enabled Office Open XML Formats, or use the legacy presentation format.

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