The first publicly released sample that The SCO Group claims was improperly added to the Linux source code has every right to be in Linux, according to open-source advocate Bruce Perens.

SCO executives released the 15-line code snippet during a keynote at the company's annual user conference, SCO Forum, in Las Vegas Monday, claiming that the code had been inappropriately copied, line by line, into Linux. The slide showing the code was photographed and published by a reporter for the German publisher, Heise, and then analysed by Perens.

The code in question was copyrighted by AT&T, whose Unix rights were later transferred to SCO, but also released under the BSD (Berkeley Software Distribution) licence, which would allow it to be included in Linux, Perens said. It represents an algorithm that can be used to manage a computer's memory, he said.

The Linux source code has been at the centre of a US$3 billion legal dispute between SCO and IBM Corp., which SCO accuses of inappropriately contributing code to the open-source operating system. SCO launched a lawsuit against IBM in March, and Big Blue countersued in August, charging SCO with patent violations, breach of contract and breach of the GNU General Public License.

SCO itself released the code to the open-source community in 2002, when it distributed its 16-bit "Ancient Unix" code under an open-source licence, he claimed.

"First of all, it's not a trade secret. Second, it's copyrighted, but used under license in Linux," he said.

SCO spokesman Blake Stowell had not viewed Perens' analysis, but he reasserted his company's belief that the code was inappropriately contributed. "At this point it's going to be his word against ours," he said of Perens.

The creator of Linux said he is not surprised by Perens analysis. "It sure as hell looks like it's BSD-licensed and has been around forever," Linus Torvalds said in an e-mail interview. "This was what we claimed was the likely source of any common code in the first place: BSD code and various vendor stuff."

Perens code analysis illustrates how important it is for SCO to make its claims public, Torvalds said. "If there is anything really suspicious, I want to remove it ASAP. But I'm absolutely not surprised at all when it turns out that it isn't suspicious."