Belgium's federal government last week approved a plan to start using the format by September 2007. The Danish government has also approved a move toward open-standard technology, as has Norway, but neither has confirmed that it will require the use of ODF.

Plug-ins could allow Massachusetts or other governments to embrace ODF without having to move workers off of Microsoft Office, a move that could require costly retraining.

Kuliks estimated it would cost an additional $125,000 to develop working converters for Excel and PowerPoint. The likely price it would charge per plug-in license would be $99 per seat, he said.

Sun's solution uses StarOffice and OpenOffice as a conversion engine. One scenario would require users to fully install StarOffice or OpenOffice on their hardware. Users could save files to ODF by choosing a separate menu item or tool bar within Microsoft Office, said Sun.

A second solution involves installing StarOffice or OpenOffice on a server. Users could still convert files by choosing a menu item within Microsoft Office or an Internet-based application such as a Web browser. This method would be compatible with service-oriented architectures (SOA) and allow users to convert multiple files at once, according to Sun.