Unix/Xenix =! Linux, which has been proven time and again by a number of developers who are familiar with the internals of both - and was the primary reason why SCO's litigation crashed and burned. Microsoft "bought" symbolic licenses from SCO early on in the McBride tenure, ostensibly for purposes of FUD generation. The entire case (from start to finish, including the MS 'license' purchase) was laid out on Groklaw.