Microsoft's declaration last week that it would finally support OpenDocument Format and join in further development of the rival document format was applauded by many critics as a major step forward, but the outcome of those steps will be under review for years to come, observers say.

After winning a 15-month acrimonious battle to get Office OpenXML (OOXML) approved as a standard by the International Standardization Organization, Microsoft last week said it would add support for alternative file formats in Office 2007 by the middle of 2009. Support for the ISO version of OOXML will likely come in the same time frame as part of the next full release of Office.

Foremost among those alternatives is ODF, which was juxtaposed as the rival format during the time OOXML was winding its way first through the standardization process at industry standards association ECMA and then at the ISO.

The European Commission, which in January opened an antitrust investigation into Microsoft Office, said in a statement that it would welcome any Microsoft effort toward more interoperability, consumer choice and less vendor lock-in.

But the commission, weary of dealing with Microsoft, added in a statement, "The Commission will investigate whether the announced support of OpenDocument Format in Office leads to better interoperability and allows consumers to process and exchange their documents with the software product of their choice."

Critics say Microsoft will be under continued scrutiny given that it does not plan to implement support for ODF for another year. The company says it will issue a Service Pack for Office 2007 that will add support for ODF, Portable Document Format (PDF) 1.5, PDF/A and XML Paper Specification (XPS), which is another Microsoft-developed format.

"If Microsoft follows through on this it is a very positive development," says Marino Marcich, executive director of the OpenDocument Format Alliance. "But I think we have seen that states, governments and others are looking for actions not words."

Marcich says that is particularly true given that Microsoft's first attempt at ODF support came via a translator that so far has garnered mixed results at best.

"It is a question of whether Microsoft is throwing ODF into the back of the bus or into the front of the bus with OOXML," says Marcich. "What do they mean by support? The devil is in the details."