Open means to be accessible in a large number of ways (here, softwares). It might be paying or not, but not trapped by a given supplier.
– OpenDocument (@wikipedia) is the ISO/IEC 26300 format used by OpenOffice.org among others. Microsoft proposes XML, however no truly open-portable-platform-agnostic format.
– Former SGML (Standard Generalized Markup Language) Open created in 1993, OASIS (Organization for the Advancement of Structured Information Standards) « drives the development, convergence and adoption of open standards for the global information society. (…). The Consortium hosts two of the most widely respected information portals on XML and Web services standards, Cover Pages and XML.org. OASIS Member Sections include Blue, CGM Open, eGov, Emergency, IDtrust, LegalXML, Open CSA, and WS-I. »
– Comparison of Office Open XML and OpenDocument | Comparison of document marked-up languages | XML (@wikipedia).
– Case studies and references to The economic impact of open data (@LinkedGov).
In short, Opendocument.xml.org gives their own presentation :
The OpenDocument Format (ODF) is an open XML-based document file format for office applications to be used for documents containing text, spreadsheets, charts, and graphical elements. The file format makes transformations to other formats simple by leveraging and reusing existing standards wherever possible.
As an open standard under the stewardship of OASIS, ODF also creates the possibility for new types of applications and solutions to be developed other than traditional office productivity applications. ODF is defined via an open and transparent process at OASIS and has been approved unanimously by the International Organization for Standardization (ISO) and the International Electrotechnical Commission (IEC) as an international standard in May 2006. It is available for implementation and use free of any licensing, royalty payments, or other restrictions.
– Liberté et non gratuité (@webOL).