The move comes as Novell works to intercept SCO's copyright claim by registering for copyrights on several versions of Unix System V with the U.S. Copyright Office over the past quarter.
Meanwhile, Linus Torvalds, creator of the Linux kernel, characterized SCO's latest intellectual property (IP) claim as technically hollow and baseless.
Nevertheless, in SCO's letter, and in a conference call held Monday to detail its latest IP claim, SCO insisted that use of its IP by Linux customers in a commercial setting violates company rights according to U.S. Copyright Law and the Digital Millennium Copyright Act (DMCA).
"Certain copyrighted application binary interfaces have been copied verbatim from our copyrighted Unix code base and contributed to Linux for distribution under the General Public License (GPL) without proper authorization and without copyright attribution," SCO writes in the letter. "The Unix ABIs were never intended or authorized for unrestricted use or distribution under the GPL in Linux.
"And distribution of Linux by a software vendor or re-distribution of Linux by an end user that contains any of the identified Unix code violates SCO's rights under the DMCA," the letter concludes.
This latest claim, separate and distinct from the contractual violation charges that SCO filed against IBM last March, maintains that the use of the ABIs by customers -- and vendors -- violates SCO's copyright rights.
SCO has not yet proved any claims against Linux in a court of law, a fact that has caused consternation among Linux vendors, customers and open source advocates who vehemently dispute all of SCO's highly publicized IP claims.
An SCO spokesman also said the company sent out hundreds of letters to Unix licensees demanding they provide written certification that each licensee is in full compliance with the AT&T Unix source code agreement. SCO has approximately 6,000 licensees total.
One spokesman dubbed the move as an "audit."
SCO claims that customers could be subject to fines of $30,000 for each instance of innocent infringement and up to $150,000 fine for willful infringement.
During the conference call Monday, SCO CEO Darl McBride said companies can avoid penalties by ceasing use of Linux, removing the offending files from the Linux software they use or by paying SCO a licensing fee.
SCO makes a distinction between what it dubs proprietary ABIs and application programming interfaces (APIs). The company acknowledges that some APIs have been made available through POSIX and other Unix open standards but alleges that the binary interfaces are protected under its ownership of Unix System V.
In an e-mail exchange with CRN, Torvalds, a fellow with the Open Source Development Labs, snubbed SCO's latest series of allegations as hollow and said the so-called violations relate to a group of simple header files, not significant IP.
"As you can see, it's basically something like five files, it's just that several of them are replicated for every single architecture out there," Torvalds wrote, pointing to the files listed on the letter. "And the thing is, those files don't even contain any code. They contain things like the error number lists -- and, yes, we made the error numbers match with traditional Unix on purpose, since, for example, Linux/alpha wanted to be binary-compatible with OSF/1. Ask any programmer what this is, and he'll tell you it's just a C header file that gives symbolic names to static error numbers."
Torvalds also said Novell apparently the SCO copyrights are being contested.
While acknowledging that filing a case against an end user is an unpopular and aggressive legal tactic, McBride claimed that IBM, Red Hat and others have exposed their customers by allegedly hiding behind the GPL. "Everyone points to a clause where they don't have liability, they are pushing the liability down to the users," he said.
Meanwhile, SCO narrowed its losses during its fourth fiscal quarter to $1.6 million from $2.7 million a year ago, although it would have reported a $7.4 million profit in the quarter before the $9 million in legal fees it paid out to fund its expanding litigation.
The price tag could get higher as SCO opponents gird for legal battle.
According to Groklaw, Novell has registered for the copyrights on Unix System V 2, 3.0, 3.1, 3.2, 3.2/386, 4.0, 4.1, 4.1ES, 4.1ES/386, 4.2, and 4.2MP with the U.S. Copyright Office during the last four months. Novell's planned acquisition of Suse Linux would make it -- along with Red Hat -- subject to copyright infingement since both vendors provide Linux distributions on the market.
And by early next month, SCO must provide IBM attorneys with the code that Big Blue reportedly donated illegally to the Linux kernel so the judge can verify if the company's claims should move forward in a Utah courtroom.
As the two prepare to face off in Utah court on Jan. 23, SCO will lay bare for attorneys key Linux code it claims IBM illegally donated to the Linux kernel, notably, the Journaling File System (JFS) code, a SCO spokesman said.
And SCO is also awaiting word on Red Hat's counterclaim, which seeks to throw out SCO's legal claims to Linux.
However, SCO's McBride said he is not intimidated by the legal backlash by key Linux vendors and that the company is serious about filing a copyright infringement case against a Linux customer no later than mid February.
He claims SCO will crush Novell's copyright claims as fraudulent.
He also claimed that SCO's rights to Unix under the DCMA will prevail over the GPL.
"We're stepping up our enforcement activities, " said McBride, noting the letter sent out last week will tie into the pending litigation. "There's a huge amount of copying of Linux going on ... copyrights are there to protect people from making copies and at the end user level is where the substantial amount of copying going on. That's the target area with litigation coming."