Users were unfazed by the latest round of saber rattling in SCO Group's intellectual property war.

In a letter to commercial Linux users distributed last week and posted online, Darl McBride, president and CEO of SCO, warned users they could be liable for intellectual property violations that, it alleges, exist in Linux source code. (See the letter). SCO's threat to commercial users comes after its March lawsuit against IBM, in which it charged that IBM misappropriated Unix code.

"We're deeply involved with Linux, and we're not turning back until the courts tell us to, which may take so much time that I'll be retired by then," says Joe Poole, technical director at Boscov's Department Stores in Reading, Pa.

"In the longer term it makes me less likely to purchase or recommend SCO products, since it appears SCO is not confident in its ability to thrive or even survive on the merits of its products and service alone," says Ian Wilson, senior consultant for Infotop Limited, a software company in Bedfordshire, England.

"I am looking into native Linux development tools and database software so that our applications can be ported to Linux without any dependency on SCO compatibility features," Wilson says. "It concerns me that SCO is acting in this way. I hope that SCO does not succeed, that the matter is resolved quickly and that SCO [will] focus on producing and supporting good quality products."

An executive from a Massachusetts software company said: "It isn't going to keep us from using Linux. This move is a necessary one on [SCO's] part to show they really believe in their legal case, even if it means losing what little [Linux] business they had."

In last week's warning, SCO said Linux's source code contains illegal inclusions of SCO Unix intellectual property.

"SCO owns the Unix operating system, and as we've been researching our suit against IBM, we've been doing our due diligence," says Chris Sontag, senior vice president and general manager of SCOsource, a business division formed to manage SCO's Unix intellectual property. "We've started identifying more and more lines of code that are derived from our Unix System V source."

Sontag says that the Linux kernel and "extended areas of Linux distributions" contain copyright violations. But he declined to say where the alleged violations are. During the next few weeks, SCO will begin to present this evidence, under nondisclosure agreement, to a select group of industry analysts, Sontag said.