Microsoft has unveiled a set of principles for future versions of its Windows operating system that aim to ensure transparency and interoperability with competitors' products. 

The vow comes as Microsoft faces wide-ranging sanctions from the European Union for failing to meet interoperability requirements. The European Commission last week imposed a €280m fine on the software firm.

Microsoft did not mention the ongoing dispute with the EU in a press release announcing the "voluntary" programme.

The tenets were described a way to guarantee openness beyond November 2007, when Microsoft's 2001 antitrust settlement with the US Department of Justice is set to expire.

But Matt Rosoff, senior analyst at Directions on Microsoft, told vnunet.com that the move is aimed in part at letting the EU know that Redmond is going to play fair with Windows Vista.

Microsoft general counsel Brad Smith said in a speech at the National Press Club in Washington: "Our goal is to be principled and transparent as we develop new versions of Windows.

"These voluntary principles are intended to provide the industry and consumers with the benefits of ongoing innovation, while creating and preserving robust opportunities for competition.

"The principles incorporate and go beyond the provisions of the US antitrust ruling."

The "principles" address developers, computer manufacturers and end users. Microsoft has promised to structure its licences for manufacturers to allow them to bundle either Microsoft or non-Microsoft products.

This would enable a manufacturer to bundle Java or the open source Firefox browser, for example, or set Google as the default search engine for Internet Explorer.