That is:
.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
See:
http://en.wikipedia.org/wiki/OpenDocument
for a partial list of applications which supports it.
Also see:
http://en.wikipedia.org/wiki/OpenDocume ... cification
How to implement it:
Very very very simple. The OpenDocument archives are in fact Zipped XML archives. In the OpenDocument/zip file there is a file called 'thumbnail.png'. This is it. Get it and use it.
To see for yourself, download an eg. odt document (for ex. http://cloudusecases.org/Moving_to_the_Cloud.odt), change the extension to zip and look inside for 'thumbnail.png'
