Confident it has proved that Novell has no claim to own Unix, SCO is now preparing for its showdown this week with IBM.

Last month Novell said that it, not SCO, retained the copyright to Unix. But last week SCO produced a document from 1996 in which a number of copyrights were transferred to it from Novell.

Novell admitted the document supported SCO's claim to some copyrights. With that argument out of the way, SCO can focus on its showdown with IBM, according to Darl McBride, SCO president and chief executive.

"Novell stood up and said we didn't own Unix. We have put that to bed and now we can focus on the breach of copyright and misappropriation of code," he said.

In a $1bn lawsuit, SCO accused IBM of breaching its contract and misappropriating trade secrets to include SCO's Unix System V source in the Linux version 2 kernel.

When SCO filed against IBM, it gave a 100-day period before it revoked Big Blue's licence to sell AIX systems. That period ends on midnight, Friday 13 June.

"We are still looking to resolve the issue with IBM but, if that fails, we have a number of options at our disposal," said McBride.

"If we reach the night of 13 June and no resolution has been found we will finalise our decision at that time."

SCO did not comment on what it would expect AIX users to do if an agreement failed to be reached by Friday. But it warned of possible repercussions for Linux users.

"We maintain that Linux users should obtain opinions from their own counsel to guide their actions," said McBride.

Analyst firm Gartner is advising AIX users to ask IBM if it will indemnify them against any potential legal action.

But whether the case will be settled or come to court remains uncertain. "IBM has deep pockets and can fight this all the way, or it could opt for a settlement," said George Weiss, vice president and research director at Gartner.

"Friday 13 June will be a major turning point in seeing how both companies will move forward."

SCO could opt to take legal action to prevent IBM from any further AIX sales affecting AIX customers, he said.

"AIX users are in a state of limbo. Even if IBM manages to get an injunction to block any potential SCO action, until it is settled there will be uncertainty hanging over future procurement of AIX."

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