The no-lawsuit agreement reached in June between Linspire and Microsoft earlier this year is almost useless to Linspire customers because of tight restrictions on what the deal covers, according to a high-profile open source legal commentator.

Microsoft on 5 July quietly published a text clarifying its agreement with Linspire, though the text only came to wider attention last week for the fact that it doesn't cover GPLv3 software.

Pamela Jones, editor of the website Groklaw, in an analysis published on Sunday, said the agreement has so many other loopholes that it is nearly useless for Linspire customers.

"With Linspire's agreement, you have to give up pretty much all your GPL freedoms, as far as I can make out, and more," she wrote. "The GPL-based development model is over for you. And what do Linspire customers get in return? Fonts. A media player. Voice over IM. What a deal."

Linspire, as well as other companies such as Xandros and Novell, have reached interoperability agreements with Microsoft, designed to help the exchange of technologies between Linux and Windows. But the deals have all been tied to patent agreements under which Microsoft agrees not to sue Linux users for what it claims are violations of Microsoft patents in open source software.

The text of the Linspire covenant reveals that the conditions under which Linspire customers are, in fact, protected from a lawsuit by Microsoft are absurdly limited, according to Jones.

She pointed out that the terms cover only certain pieces of paid-for Linspire software - not the company's free Freespire - and that significant upgrades invalidate coverage.

Coverage is also invalidated if customers themselves modify or redistribute the covered software - activities which open source licences are specifically designed to promote.

In addition, besides GPLv3 software, the agreement specifically excludes large categories of software that might be useful for business purposes - including any software running on a server, and any "business" software.

The terms of the agreement exclude "business applications designed, marketed and used to meet the data processing requirements of particular business functions," according to the covenant.

Protection runs out after three years, and Microsoft is also allowed to stop offering protection to new Linspire customers at any time, although in that case customers who had already bought covered products would keep their coverage.

Jones said the terms seemed designed to force customers to use Linspire products as though they were proprietary, or risk a patent lawsuit.

"Here's what you can still do: just sit there and don't make any sudden moves," she wrote. "Pretend you are using Microsoft software instead of GPL'd software... You have paid not only money for this Microsoft promise not to sue. You've paid with your GPL rights."

At the time the deal was announced, in mid-June, Linspire chief executive Kevin Carmony said Linspire customers would benefit from the agreement's interoperability provisions.

"This agreement will offer several advantages to Linspire Linux users not found anywhere else, such as Windows Media 10 support, genuine Microsoft TrueType fonts, Microsoft patent coverage, improved interoperability with Microsoft Windows computers, and so on," Carmony said in a statement.

Microsoft has said it expects to increase its revenues by selling patent protection agreements to an ever larger number of open source users.