Microsoft Makes XML the File Format for the Next Version of Microsoft Office: "PressPass: So what's new about the Microsoft Office XML Open Format?
Sinofsky: The Microsoft Office XML Open Format introduces significantly enhanced XML formats for Microsoft Word and Excel, and the first XML format for Microsoft PowerPoint. The formats use consistent, application-specific XML markup and are completely based on XML and use industry-standard ZIP-compression technology.
The new formats improve file and data management, data recovery, and interoperability with line-of-business systems beyond what's possible with Office 2003 binary files. And any program that supports XML -- it doesn't have to be part of Office or even from Microsoft -- can access and work with data in the new file format. Because the information is stored in XML, customers can use standard transformations to extract or repurpose the file data."