Windows Vista Metro Docs

Knowledge workers can securely collaborate by using a new, easy-to-create, XML-based, fixed-format document, code-named "Metro." This format can be created directly from any application, and is simply a page-by-page view of content as it would have been rendered by a printer. Metro documents retain all of the fidelity of the original source material and all the necessary resources such as fonts and images for rendering. In Windows Vista Beta 1, Metro documents do not require you to have the original authoring application to be viewed, but are instead viewable within the included Metro Viewer, which is hosted by Internet Explorer 7 on any Windows Vista computer with the WinFX runtime APIs installed. The Metro viewer can also be hosted by Windows XP computers with Internet Explorer 6, but likewise, WinFX must be installed. While the Metro document format is ideal for sharing content in an application-independent way, it is also an ideal archival format as well. Microsoft is freely licensing Metro, which means that the format can be created and consumed on many different platforms and classes of devices, ensuring that Metro documents will integrate well.

Information obtained from http://www.microsoft.com/windowsvista/sharing.mspx