The SCO Group Wednesday announced it was abandoning its Linux business and warned commercial Linux users they may be liable for intellectual property violations that, it alleges, exist in the Linux source code.

The move follows SCO's March 7 lawsuit against IBM, in which it charged that IBM misappropriated code it had acquired during an ill-fated effort to create a common Unix for the 64-bit Itanium chip architecture. SCO and IBM were involved in that effort.

In Wednesday's warning, SCO claimed that Linux's source code contained "illegal inclusions of SCO Unix intellectual property." SCO further claimed that commercial Linux customers could be legally liable for using this code.

"SCO owns the Unix operating system, and as we've been researching our suit against IBM, we've been doing our due diligence," said Chris Sontag, the senior vice president and general manager of SCOsource. "We've started identifying more and more lines of code that are derived from our Unix System V source," he said.

SCO is moving development, sales and marketing personnel off SCO Linux projects, effective immediately, and "suspending any activities" it had with the UnitedLinux consortium, said Sontag. The Linux staff will now work on SCO's proprietary Unix products, he said.

UnitedLinux is an effort to develop and market a standard Linux distribution, run by SCO and Linux vendors Conectiva SA, SuSE Linux AG and Turbolinux.

"Suspending any activities," however, does not mean that SCO is abandoning UnitedLinux. "We are not pulling out of UnitedLinux," because company lawyers advised against it, Sontag said.

Though Sontag claimed that the Linux kernel, as well as "extended areas of Linux distributions," contain copyright violations, he declined to say where the alleged violations have occurred. Over the next few weeks, SCO will begin to present this evidence, under nondisclosure agreement, to a select group of industry analysts, Sontag said.

One person who is particularly eager to see SCO's evidence is Linux's creator, Linus Torvalds. "I'd personally love to hear what it is they consider infringing, since I'd like to go back and see where it got adopted," he said in an e-mail interview.

Torvalds said that because of the open nature of the Linux development process, it is possible to track the origin of any section of the Linux kernel. "We've got all the history available somewhere, and it should be pretty easy to show when something was added and what the lineage was," he wrote.

The IDG News Service is a Network World affiliate.