Last year, as it was trying to come to terms with European antitrust regulators, Microsoft publicly promised to give Microsoft Office 2010 users in Europe a chance to select from various default file formats -- including the Open Document Format used by the rival OpenOffice software -- the first time they launch Office.

This "ballot screen" approach will sound familiar to anyone who followed Microsoft's Internet Explorer case in Europe, where Windows now prompts users to select one of several web browsers. Also sounding familiar will be the initial response from competitors, who say Microsoft's preview of the Office 2010 format ballot screen doesn't live up to the company's promise to be "unbiased."

Tech site Neowin, which spotted the selection screen in the Office 2010 beta in Europe last week, posted a screen shot that shows the language Microsoft is using describe to ODF in the ballot screen:

OpenDocument formats: Choose this option to set your defaults to use the ODF file formats designed to support the features of third-party productivity applications that also implement ODF. Many features of Microsoft Office are supported by ODF but some content or editability may be lost upon save.

As you might imagine, that's leaving ODF supporters feeling a bit like neighbors who were invited over for a potluck, only to have the host question the taste of their chicken salad in front of the other guests.

Neowin quotes Richard Stallman of the Free Software Foundation saying, "It is clear that Microsoft is trying to make ODF sound like a bad choice, so that few users will really use ODF. I conclude that Microsoft wants to be able to say it offers ODF support, while having few users for it."

The issue is important because document compatibility between programs can foster competition, keeping people and companies from getting locked into one particular piece of software. Microsoft Office still dominates the market, but it's facing strong competition from OpenOffice, Google Docs and many others.

Office 2010 is slated for release in June, so it isn't in final form, and there would conceivably still be time to change the ballot language. Microsoft responded to initial criticism in the IE case by changing the ballot. However, Mary Jo Foley of ZDNet quotes a Microsoft representative saying that the company doesn't currently have any plans to make changes in the Office ballot.

Microsoft offers support for ODF in the latest Office versions around the world, not just in Europe, although the OpenDocument Format Alliance has called for Microsoft to implement stronger technical support for the format. The Office 2010 ballot screen is designated just for the European market, as a result of concerns raised by regulators there. Other users around the world would need to manually change the format without prompting.

We've reached out separately to Microsoft and the ODF Alliance for comment, and we'll provide updates if the situation changes.

Update: Marino Marcich, managing director of the ODF Alliance, had this to say via email this morning:

The ballot screen, although it may at first look like it gives users a fair choice between OOXML and ODF, doesn't give ODF a fair shake, and it isn't likely to have much impact. Not only does the ballot offer OOXML as the first option, but more significantly, it provides what is essentially a warning -- OOXML is designated to support "all the features" of the software, while ODF is explained to enable "many features," but "some content or editability may be lost."

At the end of the day, the key issue here is the level of ODF support and functionality. A ballot is no substitute for a quality implementation of the format. In this case, a ballot that offers the user the choice of ODF in MS Office is only significant if the ODF support in MS Office is complete, current, and interoperable with other ODF applications. Previous attempts, in Office 2007 SP2 fell far short of this. We have not yet evaluated the level of ODF support in Office 2010."

Update 2 Microsoft's statement, echoing its comments to Neowin:

“Our customers have complex needs that no single vendor can address, so we need to be collaborative with the rest of the industry and make our products as interoperable as possible. This is why Microsoft Office has built-in support for more than 18 file formats. With Office 2010 we are continuing to deliver on our commitments to interoperability and customer choice and make it easy for customers to set their default file format in Microsoft Word, Excel and PowerPoint with this prompt box.”