SCO raised the spectre of copyright claims against Linux distributors and users earlier this year when it accused IBM of infringing SCO's rights in the UNIX operating system. SCO is suing IBM for $3 billion, alleging that IBM leaked the UNIX code in breach of a contract. SCO says that Linux contains its UNIX code and consequently is an unauthorised derivative of UNIX. In early July SCO announced that it would begin contacting companies about their use of Linux and offer them the chance to purchase a UnixWare license. The implication of this was that those companies that did not purchase the license would find themselves facing an infringement suit. SCO then announced the terms of its UnixWare license, with a promotional price of $199 for a desktop license, and $699 for a server license with one CPU. The price was due to jump dramatically after 15th October, to $1,399 for a server license, but according to CNet News, the deadline has now been extended to 31st October. SCO spokesman Blake Stowell told CNet News, "The rationale was that this pricing had not been rolled out in certain regions of the world, where we wanted to offer this introductory pricing in a timely manner". SCO has also changed its mind about the planned invoicing of commercial Linux users. Bills were expected to be sent to commercial users around the end of September but, according to the CNet report, the invoicing is no longer on the cards. "The executives have said we haven't had to do it yet," Stowell said. "They're happy with progress in the licensing program."