“Unix developer The SCO Group Inc. last week stepped up its efforts to collect license fees from Linux users and reported a quarterly net loss as a result of legal costs associated with its intellectual property rights campaign.

SCO sent out letters to selected large Linux users charging them with violations of the U.S. Digital Millennium Copyright Act. The letter outlines what SCO claims are copyright violations related to Linux. Certain application binary interfaces have been copied from SCO’s Unix System V code into Linux without proper authorization or copyright attribution, the Lindon, Utah-based company said in a statement.

The letter, dated Dec. 19 and posted to the www.sco.com Web site on Monday, includes the largest listing of alleged copyright violations provided by SCO to date. It lists 71 files from the Linux 2.4.21 kernel that, it claims, are identical to SCO’s Unix System V code. These files were allowed to be re-distributed as part of a 1992 settlement agreement between AT&T Corp. and the developers of the Berkeley Software Distribution operating system, but they may not be used in Linux, SCO said.”