Supporters of OpenDocument say a single, open standard ensures long-term compatibility, allowing archived documents saved digitally in OpenDocument to be accessible in the future. They hope that the free format will eventually become as widely used as JPEGs and GIFs are in the graphics arena.

But the plan has drawn ire from some Massachusetts politicians, who think the state is interfering in the free market, as well as groups representing people with disabilities, who say OpenDocument fails, for example, to support text-to-speech features crucial to blind users as well as Microsoft Office does.

Microsoft, which claims there are more than 400 million Office users worldwide, is supporting a new format native to Office 2007, OpenXML, which it is promoting for acceptance as an open standard.

Alan Yates, general manager of Microsoft's information worker business strategy, said Microsoft welcomes the plug-in. "We have always expected that third parties would work on this set of issues and create bridges between the two sets of XML-based formats," he said.

There are other alternatives besides Edwards' plug-in. For example, a New Zealand-based open-source project has developed free software that's designed to convert Microsoft Word files into OpenDocument. According to the project'sWeb site, the software, called DocVert, "generally" works, though "some embedded objects within MSWord may not convert successfully." However, DocVert is not conveniently embedded into Microsoft Word; it is run separately.