SCO cancels Sequent's Unix licence

SCO, owner of several key copyrights related to the Unix operating system, has been aggressively defending its intellectual property holdings connected to the software and filed a $3bn (£1.87bn) lawsuit against IBM earlier this year. The suit claims that IBM has committed trade-secret theft and breach of contract for allegedly copying proprietary Unix source code into its Linux-based products.

The company reported that it terminated Sequent's Unix contract for improper transfer of source code and development methods into Linux. Based on the move, SCO claims that IBM no longer has the right to use or license Dynix/ptx, and said that customers should not be able to acquire a licence for the software.

Sequent representatives could not immediately be reached for comment on the SCO announcement.

SCO said it gave Sequent-IBM two months' written notice prior to the termination, as required by the terms of the contract. The company claims that Sequent-IBM chose not to address the purported breach of contract and did not offer any resolution to the disagreement.

The System V contract allowed Sequent to market derivative works and modifications of Unix software "provided the resulting materials were treated as part of the Original System V Software," according to SCO.

Earlier this month, an IBM executive downplayed the threat of the pending SCO lawsuit, telling attendees at the LinuxWorld Conference and Expo that the case would become a forgotten chapter in Linux history. However, IBM did file a countersuit rebutting SCO's claims.

Other Linux industry players have also responded to SCO's intellectual property suit aggressively. Red Hat, one of the two major distributors of Linux software, filed its own countersuit demanding that SCO retract its copyright infringement claims.