Details of SCO's evidence in its multi-billion dollar suit against IBM are beginning to emerge, but analysts remain split over SCO's chances of winning.

The lawsuit claims that IBM broke its contract with SCO by allowing parts of SCO's Unix V source code, licensed to IBM for use in AIX, to be used in the rival Linux operating system kernel.

In the past few weeks, SCO has been showing evidence of its case against IBM to selected analysts. Some examples of what it considers to be appropriated code are now emerging.

Source code delivering non-uniform memory architecture (Numa) and symmetric multiprocessing capabilities in Linux are very close to those in SCO's System V source code.

But analysts indicated that ownership of the code is far from clear.

Sequent Systems developed the NUMA technology and was subsequently acquired by IBM in 1999. "IBM can argue that SCO has no rights concerning that code," said George Weiss, vice president and research director at Gartner.

SCO insists that, although companies contributing code to Unix maintain ownership, control of its use remains with the owner of Unix.

This means that the case could be less about straight duplication than about the nature of SCO's licensing contracts.

The company admits that its contracts are tight as they date back to Unix's original owner, AT&T.

"In the 1970s and 1980s AT&T was extremely powerful and was able to insist on strict language in its contracts," said SCO spokesman Blake Stowell.

According to analysts that language could prove too strict. "SCO will have to prove to a jury that it has not made unreasonable demands," explained Weiss.

Even if SCO can defend its licensing terms, there could be real problems in proving its claim for billions of dollars in damages.

"Despite Linux, there is still a strong Unix market with many competitors," said Weiss.

In addition, the analyst maintains that there is little evidence that SCO's Unix offerings - SCO Open Server and UnixWare - could ever have built a sizeable market share even if Linux never existed.

"It is far from clear that they have built a scaleable 64-bit operating system for the marketplace even now," said Weiss.

Other analysts are less certain. "SCO Unix revenues went from $200m-$250m in 1999 to $60m. That could certainly be considered material impact," stated Laura DiDio, senior industry analyst at the Yankee Group.

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