Belgium has become the first country to mandate the use of the OpenDocument format (ODF) for office files, albeit tentatively.

From September next year software in all Belgian government departments must be able to read ODF files. If the experiment is successful, ODF will become the standard interchange format - although departments will still be able to exchange office files in proprietary formats internally.

Early last month the ISO voted unanimously to approve the OpenDocument format - an XML specification that originated from Sun's OpenOffice project, and which for a time was known as Open Office XML.

Although Microsoft hasn't changed its Office file formats since 1997, it's fighting OpenDocument with its own rival XML interoperability initiative, on the grounds that the new ISO format "stifles innovation". Microsoft is also pushing its own XML format through the ISO standardization tracks.

It's the most significant federal mandate yet, following the trail blazed by the US state of Massachusetts. An immediate problem facing adopters is that the most up to date version of Microsoft Office, Office 2003, doesn't natively support ODF.

Massachusetts state IT department published a Request For Information for an Office plug-in last month. In response to the RFI, Microsoft says it's supplying technical documentation and granting IP rights to any developers who want to work on such a plug-in.

It's also given Massachusetts state education software licenses worth $30m - or $800 for each college student and $2,400 for each student in further education. ®