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 Inc., who argue that its open, interoperable nature makes it suitable for organizations concerned about long-term archiving of files.

Microsoft, whose market-leading Office suite is used by more than 400 million people worldwide, has said the 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 e-mails 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.