No move by Microsoft to share information with its competitors will ever be taken at face value, and certainly yesterday's new Interoperability Principle will come under very close scrutiny. Is this the opening of the floodgates the EC has been demanding?

In incremental, measured, if slow steps, Microsoft has made some efforts to comply with directives from the European Commission to make its software and protocols more interoperable with products from other manufacturers. Yesterday, the company surrendered one more boundary between its interoperability policy and the EC's dream situation, making a huge chunk of the information it published in response to the EC's order available to developers free of charge.

The company's newly published Interoperability Principle spells out the terms to which Ballmer referred: "Microsoft will publish its documentation for these Open Protocols and Open APIs on its website so that all developers will have the benefit of this technical information in a manner that takes advantage of the nature of open discussion on the web. Microsoft will not require developers to obtain a license, or to pay a royalty or other fee, to have access to all this information."

But free access, the Principle makes clear, does not mean free use. While Microsoft will no longer charge fees or royalties for parties seeking information on how to make their software interoperable, it may yet charge royalties for the way others use that information.

"Some of Microsoft's Open Protocols are covered by patents," reads the Principle. "Microsoft will indicate on its website which protocols are covered by Microsoft patents and will license all of these patents on reasonable and non-discriminatory terms, at low royalty rates. To assist developers in clearly understanding whether or not Microsoft patents may apply to any of the protocols, Microsoft will make available a list of the specific Microsoft patents and patent applications that cover each protocol."

The use of APIs to access those protocols, however, will not require a license, even if the service with which software is communicating is itself protected by Microsoft patents. So the company is making it clear, interoperability will not require licenses or incur fees, but like operability (building a product using a design inspired by Microsoft's patented IP) may very well.

The Principle does specify the products to which it applies: "Windows Vista including the .NET Framework, Windows Server 2008, SQL Server 2008, Office 2007, Exchange 2007, and Office SharePoint Server 2007, and future versions of these products." Previous editions of those products were not listed.

But while Ballmer and others referred to Office 2007 interoperability yesterday, there actually was no mention of Open Document Format, the basis of competing applications suites and the first such format to receive international standardization. Microsoft did open up access -- or at least, open it up somewhat more -- to its principal current products, so it did specify the "to what" part of the change argument, to borrow Rep. Barbara Jordan's famous phrase once again. But it did not specify the "from what."

Thus the status of an ODF plug-in for Office 2007 was not clarified yesterday, even though some got the impression that's what Ballmer was referring to.

The absence of any such mention was not lost on Red Hat chief counsel Michael Cunningham, in a response posted to his company's Web site yesterday afternoon.

But Linux Foundation board member and attorney Andrew Updegrove thought yesterday's announcement was about ODF, in a sense...for the way in which it skillfully omitted mention of it.

"With respect to ODF, it will be important to see what kind of plug ins are made available, how they may be deployed, and also how effective (or ineffective) those translators may be," Updegrove said yesterday, in a statement shared with BetaNews. "If they are not easy for individual Office users to install, or if their results are less than satisfactory, then this promise will sound hopeful but deliver little. I am disappointed that the press release does not, as I read it, indicate that Microsoft will ship Office with a 'save to' ODF option already installed. This means that ODF will continue to be virtually the only important document format that Office will not support 'out of the box."'

The fact that Microsoft's making any movement in this direction at all, Updegrove added, is an indication to him that "multiple market forces" -- which, he said, included the EC investigation and the popular uprising of ODF support -- "are pushing and pulling Microsoft in a direction that it would have been highly unlikely to travel otherwise."

Yesterday's statement from the European Commission apparently was intended to serve as a reminder to everyone, including Microsoft, that its definition of "interoperability" is deeper than the mere dissemination of APIs. It said its current investigations are focused on "the alleged illegal refusal by Microsoft to disclose sufficient interoperability information across a broad range of products, including information related to its Office suite, a number of its server products, and also in relation to the so called .NET Framework and on the question whether Microsoft's new file format Office Open XML, as implemented in Office, is sufficiently interoperable with competitors' products."

Microsoft's APIs, as defined yesterday, provide open access by software with other software for the purposes of sharing information and functionality -- which is actually the way professional developers typically understand APIs and interoperability to work. But the legal definition is often fuzzier, as indicated by the EC's reminder yesterday that Microsoft needs to make its OOXML file format -- as opposed to Office 2007, the software which utilizes the format -- "sufficiently interoperable."

That would require not an API as Ballmer describes it but a plug-in as Updegrove describes it. Microsoft has said it is participating with open, community efforts to produce such plug-ins, though critics continue to question why the company doesn't just produce one on its own. Backers of Microsoft's efforts pose the counter-argument that it shouldn't be Microsoft's responsibility to ensure one-to-one correlation between its own format and every other one that comes along, whether or not it's an international standard.