One of the first observers to see the evidence in the SCO Group's intellectual-property claim against IBM and the Linux community says there are direct similarities between the Unix code that SCO claims control over and the Linux operating system.

"My impression is that [SCO's claim] is credible," says Laura DiDio, a Yankee Group analyst who was shown the evidence by SCO Group earlier this week. "It appears to be the same" code. But DiDio says the developing battle could hinge on legal fine points that are hard to sort out in the current atmosphere of claims, denials, and counterclaims.

Apparently the most telling evidence is that parts of the SCO code and Linux code include identical annotations made by developers when they wrote the programs, says DiDio, who compares such notes to the signature or fingerprint of a developer's work. "The fact that these appear to be transposed from Unix System V into Linux I find to be very damaging." DiDio says she was shown several instances where the source code and developer's comments in one operating system were the same as in the other operating system.