A group of software and technology companies have joined the European Commission’s anti-trust case against Microsoft.

The European Committee for Interoperable Systems (ECIS) includes IBM, Oracle, Nokia, Red Hat, and RealNetworks.

The participation of these companies in the case will serve to add credibility to the case, credibility which was lessened after Sun, Novell, and the Computer and Communications Industry Association dropped out of the case after settling out of court with Microsoft.

It is not sure that the ECIS will be granted the right to officially join the proceedings, as it missed a filing deadline with the court.

But the ECIS will still be able to lend technological and legal advice, lost when the other concerns dropped out, on an unofficial basis if they are not granted official standing.

In addition, even if not granted official standing, the ECIS can also still apply to participate in the oral arguments on the appeal.