"United Linux was an attempt by a consortium of Linux distributors to create a common base distribution for enterprise use, so as to minimize duplication of engineering effort and form an effective competitor to Red Hat. The founding members of United Linux were SUSE, Turbolinux, Conectiva (now merged with MandrakeSoft to form Mandriva) and Caldera International (later renamed to The SCO Group). The consortium was announced on May 30, 2002. The end of the project was announced on January 22, 2004."

It never really worked from a business perspective but Caldera becoming faux-SCO was pretty much the final straw.