Who Owns UNIX?
The UNIX code has a complex ownership history. To understand SCO's claim to own the original UNIX code, we need to trace the chain of title that's illustrated by the flowchart in Figure 1.
Bell Laboratories originally developed and owned the UNIX code. In 1984, a court order broke up Bell Systems, and AT&T received ownership of the UNIX code. In February 1985, AT&T granted to IBM a nonexclusive license to the UNIX System V source code. AT&T also had a similar contract with Sequent, later acquired by IBM, which licensed Sequent's version of UNIX (called Dynix/ptx).
In 1990, AT&T reorganized its business and transferred title to UNIX System Laboratories, Inc. (USL), a new wholly owned subsidiary. In 1991, Novell and USL formed a joint venture called Univel, and USL contributed its rights to UNIX to the joint venture. Two years later, Novell bought out USL's interest in Univel and renamed it the Novell UNIX Systems Group. In 1994, Novell transferred the UNIX trademark to X/Open (now called The Open Group). In 1995, Novell sold UNIXWare (Novell's variation of UNIX) and the original Bell Labs version of UNIX to SCO. In 2001, SCO sold the SCO brand, SCO OpenServer (SCO's version of UNIX), and the Bell Labs version of UNIX to Caldera, which now does business under the SCO name.
Through this series of transactions, SCO believes that it acquired all of the rights to the UNIX code and has assumed all of the licensing and sublicensing agreements granting third-party rights to UNIX. For example, SCO believes that it has assumed AT&T's rights under the licensing agreement between IBM and AT&T from 1985.
However, there remain significant disputes over what rights SCO acquired and how Linux infringes those rights. Twice, SCO has offered proof that Linux contains code copied from the original Bell Laboratories UNIX code base. The first time, SCO showed Linux code that appears identical to UNIX, even including developer comments and spelling errors from the original UNIX code. In December 2003, SCO claimed that portions of 72 Linux files had been copied verbatim from SCO's "copyrighted UNIX code base." In response to each SCO offer of proof, the open source community declared that SCO does not own the code it claims was copied-and, even if it did, the code was traceable to other legal UNIX sources.
SCO's rights may also be limited by the terms of a confidential 1993 settlement agreement that derives from a lawsuit SCO's predecessors (USL and Novell) brought against the University of California Berkeley and Berkeley Systems Development (among others) over another variation of UNIX called 4-4BSD. Because the case file was sealed, we don't know what USL/Novell agreed to, but the continued public availability of BSD may favorably affect other variations of UNIX as well.