Microsoft has lodged a new appeal against the European Commission's anti-trust ruling.

"Microsoft has filed an application for an annulment with the Court of First Instance specifically concerning the issue of broad licenses for the source code of communication protocols," said spokesman for the software giant. "This filing is the result of the agreement reached with the Commission in June to put this particular issue to the court for guidance and to avoid further delay in the process."

The decision to file a new appeal follows a letter sent by the European Commission to Microsoft on 1 June, saying that it did not accept the terms under which the company was prepared to make available the communication protocols for its workgroup server software.

Microsoft has refused to allow its source code to be licensed under the General Public License (GPL), which gives users the right, among other things, to freely modify and redistribute software, like most open-source software.

The Commission, the European Union's executive branch and market regulatory body, agreed that this issue would be settled by the European Court of First Instance, which is hearing Microsoft's appeal of the anti-trust ruling.

"We are taking this step so the court can begin its review of this issue now, given its far-reaching implications for the protection of our intellectual property rights around the world," Brookes said.

In June, the Commission announced that Microsoft had agreed to make a number of changes to the terms on which it grants access to its protocols - though the company still did not agree to license the protocols for use in open-source products. The Commission maintained, nevertheless, that if the court upheld the Commission's ruling that protocols should be available, they should be publishable under GPL terms, provided they did not embody "innovations".

Meanwhile, the Commission continues to seek response from Microsoft rivals and other industry players about the terms that Microsoft has offered.

An independent monitoring trustee will have the job of deciding whether Microsoft is complying with the Commission ruling and will also evaluate which parts of the protocols are innovations and identify whether the fees Microsoft is planning to charge for some of the protocols are reasonable.

The Commission and Microsoft have not yet agreed on who should be appointed as trustee.

Hearings on Microsoft's appeals are not expected to start until next year. The hearing and final ruling are expected to take up to four years.