OpenXML
From Apache OpenOffice Wiki
OpenXML is the Microsoft Office 2007 XML based file format that has been published as ECMA-376.
There are plans to support this file format in OpenOffice.org for interoperate with Microsoft Office 2007
There are 3 major types of files
There is some code in the oox module from the Xml project. The CWS is xmlfilter02 in SRC680. (view the workspace on EIS)