A very good question, but I'm not sure if it would be useful. I don't know if this is true or not ("I think I'm right but don't quote me"), but I think that UN

A very good question, but I'm not sure if it would be useful. I don't know if this is true or not ("I think I'm right but don't quote me"), but I think that UNIX certification applies to the effective equivalent of "that bunch of files over there". Change the checksum and the certification doesn't apply anymore. Yay. But it's not the end of the world. The people that want to buy UNIX licenses - Solaris, HP/UX, AIX, z/OS guys, etc - are those steeped in vendor lockin from legacy systems. The number of people still part of that tradition is decreasing; most new tech stacks are built on Linux, and its new mindset. So, a UNIX cert for Linux would ultimately be 95% geek cred, 4.9% "oh hey, let's go this way" for those from the aforementioned groups who want familiarity, and 0.1% practical in terms of ROI. Once the personal status quo of each individual in those groups shifts so that UNIX won't pay their bills anymore, those who wants to keep their jobs will switch. NB. I know this comment is mildly flat in terms of only looking at this from one angle. I don't have any experience or knowledge to comment on the many other interpretations of the issues I've mentioned, replies are welcome to do so.