Microsoft’s decision to finally support the open source Open Document Format (ODF) standard via a plug-in to Office is very good news, and the company should be commended for it. But there may be a little less here than meets the eye.

Microsoft finally backs ODF because of pressure from other countries, and also from my home state of Massachusetts, although there are some who might claim that Massachusetts is a foreign country as well.

ODF was approved by the Organisation for the Advancement of Structured Information Standards (OASIS) as a standard last year, and is also supported by IBM, Sun and Novell.

But what does supporting the standard actually mean, in Microsoft’s case? It’s not completely clear yet. The company has only announced support for the Sourceforge Open XML Translator project, which translates only between between ODF and Word 2007. Excel and PowerPoint support is in the works, but not yet finalized.

The Word translation add-in is expected to be available for free by the end of 2006. Microsoft says add-ins for Excel and PowerPoint will be released some time in 2007.

But beyond that, a Microsoft press release warns, “Certain compromises and customer disclosures will be a necessary part of translating between the two formats.”

What exactly does that mean? It could just be boilerplate that lawyers insisted be slipped into the relase — or it could be that there really will be compatiblity issues. We’ll have to wait to find out.