Seven companies have responded to a call by Massachusetts officials for information on software plug-ins that would allow Microsoft Office users to read and write files in the OpenDocument format (ODF). Among those that replied are Sun, a strong proponent of ODF, and Microsoft, a strong opponent.

Sun and five other companies have created plug-ins that create compatibility between Office file formats and ODF, a free XML file standard based on the open-source OpenOffice.org productivity software suite. ODF was ratified as an open standard by the International Organization for Standardization (ISO) in May, according to information posted on the website of the state's IT Division.

Meanwhile, Microsoft said it is freely supplying technical documents and intellectual property rights to third-party developers working on such a plug-in.

Those developers include Sun, which said it has created two ways to convert any Office file to ODF using its own StarOffice software; OpenDocument Foundation, that said it has developed converters for Microsoft Word and Excel files and is now working on PowerPoint; and four smaller companies, all of which have developed file converters for Word, Excel or PowerPoint, but not all three.

Media Entities is typical: the two-person firm sells to publishing companies a high-priced XML file converter that can convert Microsoft Word files to ODF, said Bruce Kulik, the company's chief technology officer. "We read about this in the trade press and thought, 'Hey, we're in Massachusetts. Why don't we offer them what we've got?'" Kuliks said. "We're not big OpenOffice fanatics. But if the state wants to get out from under the Microsoft monopoly, we can provide the technology."

Massachusetts plans to make ODF its standard method for exchanging all official government documents by 1 January.

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 licence 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.

Sun said it only needs to make its converters work within the Microsoft Office interface. They could be ready for testing in two months and available for customer use a month later, the company said.

ODF is the default file format in OpenOffice, StarOffice and an increasing number of Web-based word processing and spreadsheet applications. Though used by only a small percentage of users worldwide today, ODF is supported by vendors such as Sun, IBM and Novell, who argue that its open, interoperable nature makes it suitable for organisations concerned about long-term archiving of files.

Microsoft, whose market-leading Office suite is used by more than 400 million people worldwide, has said ODF stifles innovation and customer choice. It is developing a competing format, OpenXML, that will debut in its forthcoming Office 2007. Microsoft has garnered the support of other vendors for OpenXML and is applying to ECMA International, a rival standards body to ISO, for certification as an open standard.

While Kuliks said he has only exchanged emails with Massachusetts officials, other developers, such as Gary Edwards, head of the OpenDocument Foundation, said he demonstrated his plug-ins to officials last week.

"They've been incredibly systematic, throwing hard stuff at us," he said, noting that his plug-in enables Microsoft Office to open a 16,000-row spreadsheet saved in the ODF format in 31 seconds. Opening the spreadsheet in Excel takes 43 seconds, he said.

Despite Microsoft's concerns that the rise of ODF could prove problematic for Office in the marketplace, Edwards said Microsoft was very helpful with his development efforts. Microsoft has "the best third-party developer model," he said. "They gave us what we needed, and it works beautifully."

Sun, meanwhile, said it can't guarantee that its plug-in will be able to save to ODF by default because of "information about the MS Office application that is not generally available."

"Our technical engineers feel that the ways for accessing the range of interface options in Office [are] not fully documented and fully committed to," said Douglas Johnson, corporate standards program manager at Sun. "We don't think Microsoft Office is too proprietary. We know it is."

Sun also said that it may not be able to guarantee that Office files converted to ODF retain all of their formatting and other information due to "technical or intellectual property-related reasons" related to Microsoft.