(1) For the compound document format, see
OpenDoc.
(2) An XML-based file format for office applications standardized by OASIS in 2005 and ISO in 2006. Officially the "OpenDocument Format for Office Applications," OpenDocument is supported in OpenOffice, StarOffice and other word processors as well as text-based applications.
An Open Standard
OpenDocument was designed to be used without licensing restrictions and is an alternative to Microsoft's proprietary Office formats as well as Open XML.
A Lot of "Open" Formats
The Apache OpenOffice suite supports the OpenDocument format; however, OpenDoc and Office Open XML are not related to OpenDocument. See
Apache OpenOffice,
OpenDoc and
Office Open XML.