The SCO Group is sticking to its ultimatum of revoking its licence to IBM for the use of Unix, which is set for next week.
Unless IBM corrects the wrongdoing charged by SCO by midnight, or settles the case, SCO intends to revoke the licence it sold to IBM and weigh up its further legal options.
"They need to correct their actions as outlined in our complaint. If those terms aren't met, then we will announce what our actions are on Monday," said SCO spokesman Blake Stowell. "We would intend to revoke the AIX licence."
AIX is IBM's flavour of Unix, but SCO owns the rights to some elements of Unix. Revoking the licence would invalidate all AIX customer licences, so users of the software would be operating with an invalid licence, according to SCO.
AIX is sold with IBM's pSeries servers and other products.
SCO sued IBM in March, claiming that IBM used proprietary Unix code for the open-source Linux operating system, violating the Unix licence agreement in the process.
SCO seeks at least $1bn in damages and set a 100-day deadline for IBM to cease its "anticompetitive" practices.
IBM denied the charges brought by SCO and does not believe its licence can be revoked.
"IBM believes that our contract is irrevocable and perpetual," IBM spokeswoman Trink Guarino said. "IBM will continue to ship, support and invest in AIX."
Joris Evers writes for IDG News Service