Microsoft Office 2007 introduced new Open XML-based file formats for Office applications. These new file formats reduce file size, improve security and reliability, and enhance integration with external sources. To allow Windows Mobile users to work with Office documents created in the Open XML formats, Microsoft has developed an upgrade for Word Mobile, Excel Mobile, and PowerPoint Mobile applications. This upgrade to the Office Mobile applications allows viewing and editing of Word documents and Excel workbooks and viewing of PowerPoint slideshows created by using Microsoft Office 2007.