Specifications
The most common filename extensions used for OpenDocument documents are:
.odt
and.fodt
for word processing (text) documents.ods
and.fods
for spreadsheets.odp
and.fodp
for presentations.odb
for databases.odg
and.fodg
for graphics.odf
for formulae, mathematical equations
The original OpenDocument format consists of an XML document that has
as its root element. OpenDocument files can also take the format of a ZIP compressed archive containing a number of files and directories; these can contain binary content and benefit from ZIP's lossless compression to reduce file size. OpenDocument benefits from separation of concerns by separating the content, styles, metadata, and application settings into four separate XML files.
There is a comprehensive set of example documents in OpenDocument format available. The whole test suite is available under the Creative Commons Attribution 2.5 license.
Read more about this topic: OpenDocument