OpenDocument
Open Office XML will be an open document file format for saving office documents such as spreadsheets, memos, charts, and presentations. It is being developed by OASIS. The new format is based on, and remains extremely similar to, the XML-based file format developed by OpenOffice.org.
While Open Office XML has not yet been formally released, a "committee draft" of version 1.0 of the specification has been approved by OASIS and is available for free download.
The Open Office XML format is intended to provide an open alternative to proprietary document formats including the popular DOC, XLS, and PPT formats used by Microsoft Office. Organizations and individuals that store their data in an open format avoid being locked in to a single software vendor, leaving them free to switch software if their current vendor goes out of business or changes their software or licensing terms to something less favorable.