To pick nits with the whole "unix-based" comment, Linux wouldn't qualify for the label of Unix-based. It's a clean implementation to be UNIX-LIKE. Unix-based would imply there is some code lineage carried over from SysV or BSD, which was the crux of SCO's argument that there was some cross-pollination(or more appropriately contamination) of copyrighted "UNIX" code. I think Apple was riding on a technicality with the previous usage of UNIX-based in the past. IIRC NeXTSTEP which is the basic for Mac OS X, has some roots in the original BSD tapes. Mac OS X 10.5 on Intel machines is now an official card carrying certified UNIX and their site has dropped reference to the "UNIX-based" and states it plainly as UNIX. In all fairness though, I don't think it would be much of a stretch for Linux to pass the UNIX certification process but there isn't any one to cough up the funds for the certification process itself since every distro would have to probably pay and certify separately. I'm sure someone like CentOS would't be able to ride RedHat's coatails if RH certified RHEL with the Open Group. »