The letters were brought up during a hearing in which U.S. District Judge Dale Kimball was considering motions by the two software companies, including one in which SCO asked him to rule that it does not owe Novell fees that SCO collected for licensing the Unix operating system to Microsoft, Sun and others.
In the trial, Novell is seeking $19.9 million, the result of Kimball's decision last year that Novell still owned pre-1995 copyrights to the Unix system that it sold that year to The Santa Cruz Operation. Lindon-based SCO bought the system in 2001 from Santa Cruz, believing it owned all of the copyrights to the system used by businesses to run their computer operations.
Referring to the letters, Novell attorney Michael Jacobs told Kimball the issues in the trial needed to be sorted out "before we create our own imbroglio in the computer industry."
Jacobs was comparing Novell's possible claims against Microsoft and Sun to the controversy SCO sparked when it sued IBM in 2003. SCO claimed that IBM had used the Unix source code - the backbone of a computer operating system - to make enhancements to the Linux operating system that made it able to compete with Unix.
SCO also sent letters to large companies saying they potentially owed SCO licensing fees for use of Linux operating systems that included Unix code.
Jacobs declined after the hearing to elaborate on his remarks or the letters sent by Novell, which was founded in Utah and still has it largest office in Provo, although its headquarters are now in Massachusetts.
Jacobs told Kimball that SCO had sold Unix licensing to Microsoft at a "fire sale" price in a 2003 agreement in which SCO relinquished all claims it might have to Unix code that is found in Microsoft products.
"SCO gave Microsoft basically undiluted rights to do what it would," Jacobs said.
The 2003 Sun Microsystems license allowed Sun to open up its Solaris operating system code to the public, even though it contained Unix code.
Calls to Microsoft and Sun officials seeking comment Wednesday were not returned.
In earlier testimony Wednesday, SCO Group CEO Darl McBride tried to bolster SCO's claims that it bought all the copyrights to Unix when it purchased the system in 2001.
SCO pointed to letters Novell sent out in 1996 in which it told customers it had transferred "existing ownership interest" in Unix to Santa Cruz.