The expected approval of the GPLv3 (GNU General Public License version 3) could further muddy the waters for Microsoft's claims it will collect payment on its patents for Linux technology, as there is a question about whether the company's interoperability deal with Novell will violate the forthcoming final draft.

The current version of the GPL, the open source license for Linux, does not have specific protection against patent litigation for companies distributing Linux. However, GPLv3, which is expected to be in final release in the next couple of months, has a provision promising patent safety to those who receive software, such as Linux, distributed under the license.

The provision was put in specifically to make deals such as the one Microsoft struck with Novell "useless" to Microsoft so that it cannot make similar pacts that include royalty payments with other companies, said Eben Moglen, chairman of the Software Freedom Law Center and a Columbia University professor of law and legal history who cowrote the GPLv3 draft with the Free Software Foundation's Richard Stallman.

"Rather than discriminating among parties so customers feel safe [from litigation] and not developers, we instead will be turning the Microsoft-Novell deal into a patent-insurance factor for everybody," he said.

The catch is that no one is sure if Microsoft's agreement to distribute coupons for Suse Linux Enterprise Support through the Novell deal would deem it a Linux distributor and require the company to be compliant with the GPL. And Moglen, who has examined the Microsoft-Novell deal but is under a nondisclosure agreement forbidding him from revealing specifics, said that the answer will remain unclear unless Microsoft and Novell go public with that element of their deal.

Microsoft declined to comment on the issue Wednesday through its public relations firm on the grounds that GPLv3 is still in draft form. However, Moglen thinks the company is being deliberately vague about compliance with GPLv3 for the same reason it said this week it would seek royalties on technology in Linux it claims to hold patents for: To cause fear among customers who want to adopt Linux and other open source software over its commercial products.

"They have to climb out of the car crash that is [Windows] Vista and go out and spend hundreds of millions of dollars to make software the way they should make it," he said. "Vista has nothing that isn't available for free. Microsoft must come out and start again from behind, and it's not a position they've been in before. It's not a position in which they can compete successfully."

There also is a question of how a court would interpret Microsoft's deal with Novell and the GPLv3 provision if it should ever be raised as a key issue in patent litigation.

"There's a clever attempt in the latest GPLv3 draft to ensnare a company just for promoting a GPLv3 product, but this will never hold up for any number of reasons," said Jonathan Zuck, president of the Association for Competitive Technology, an advocacy group in Washington, D.C., that formed in the wake of the government's antitrust case against Microsoft. The company is a member of the group. "It's hard to imagine where giving out support coupons constitutes product promotion."

That could be one view a court would take, agreed Andrew Updegrove, an attorney with Gesmer Updegrove LLP in Boston. But it's hard to predict how any particular legal authority would view the definition or the provision if it were challenged, he said.