REDMOND, Wash. (AP) — Microsoft Corp. said Thursday it will share more information about its products and technology in an effort to make it work better with rivals' software and meet the demands of antitrust regulators in Europe.

European Union regulators, however, expressed skepticism, saying the software maker did not touch on possible monopoly abuse in the past, or address allegations it seeks to undercut rivals by illegally giving away its Internet Explorer browser with the Windows desktop operating system.

Microsoft said it is expanding access outside software developers have to information about the way its programs work. Microsoft said it will give away documentation and computer code needed to make outside applications work together with its Office suite, Windows operating system and others. In the past, Microsoft charged for the information.

The company will still charge a patent license fee to companies that want to sell software built using this information. But Chief Software Architect Ray Ozzie described the fees as ''low royalty rates.''

Microsoft said it posted 30,000 pages of documents online that will help level the playing field for non-Microsoft developers. Bob Muglia, a senior vice president of Microsoft's server and tools business, said in an interview that those documents spell out exactly how the company's programs work together _ allowing, for example, another company to build an e-mail system that works as well with Outlook as Microsoft's own Exchange Server.

Steve Ballmer, Microsoft's chief executive officer, said in a news conference that the move could boost rivals' ability to compete. But he said it also opens up Microsoft's platform for developers to build products that could keep users interested in Windows PCs — an essential ingredient if the company is going to survive an industrywide shift toward Web-based programs that don't require a particular operating system.

Ballmer said the decision will have a relatively minimal impact on Microsoft's revenue.