The Open Document Format (ODF) is an open source standard for office documents (text, spreadsheets, presentations etc.). It is used e.g. by OpenOffice or StarOffice and other similar open source tools. Since Microsoft Office 2007 started its own (only partially open...) XML format called "OpenXML" there is a "war of formats" going on because each standard tries to become THE standard for office documents. eLML offers a ODF converter because the team thinks that ODF is the better standard and deserves support from the open source community. Read this comparison to know more about the differences between ODF and OpenXML. There are many tools around to convert one format into another one and good office tool even support both by default so don't worry :-)
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