The SCO Group is presenting its case against the Linux operating system and IBM by spending a month showing evidence to analysts.
Last week, the company began showing code to US analysts which, it claimed, proves that the source code to the Linux operating system contains sections of code lifted directly from SCO's Unix code base.
SCO's presentation, which has been seen by analysts at Gartner and Aberdeen Group, features pieces of software that IBM contributed to the Linux code base, SCO said.
That code was derived from SCO's Unix code, itself derived from AT&T's System V Unix code, and then distributed to the Linux community in violation of SCO's licensing agreement, the company claimed.
SCO will spend June showing its evidence to analysts and journalists, said SCOsource general manager Chris Sontag.
"The one specific example that I'm showing right now is [Unix] code, line by line copied into Linux," said Sontag. He said that this code, which SCO considers to be a copyright violation, is identical in both the Linux and SCO code base.
Sontag would not say which specific parts of Unix SCO believed has been copied, but he did say that the work appeared to have been done by a company other than IBM.
SCO sued IBM for $1bn (£604m) in March, charging the company with misappropriation of trade secrets, tortious interference, unfair competition and breach of contract.
SCO claimed that IBM's 1985 Unix licence, originally signed with AT&T, but subsequently transferred to SCO, prevented IBM from distributing software derived from the Unix code base.
IBM's contributions to Linux in the areas of non-uniform memory architecture (NUMA), symmetric multiprocessing (SMP), and a journaling file system all constituted breaches of that contract, Sontag said.
SCO intended to revoke IBM's Unix licence, "due to their breach of the contract that they have with us", Sontag said .
IBM has denied engaging in any wrongdoing in the case.
SCO was able to uncover the alleged violations by hiring three teams of experts, including a group from the Massachusetts Institute of Technology mathematics department, to analyse the Linux and Unix source code for similarities.
"All three found several instances where our Unix source code had been found in Linux," said an SCO spokesman.
Open-source advocates said that it was no surprise that Linux and System V share similar code, since they both include components of the Berkeley Software Distribution (BSD) code base.
"It's clearly a fact that [Unix] contains a lot of BSD code, and Linux has some too, so there are bound to be... lines of code in common," wrote Linux creator Linus Torvalds.