Nice try, numbnuts.
That's from 1983. SysV R4 was issued in … 1988. Now HP/UX was pretty good, better than the SysV R3 it was based on, in 1983, but I'm fairly sure it didn't have time travel capabilities. It may not have actually moved to the SysVR4 codebase, I'm not sure*, but it certainly moved to a SysVR4 system and userland layout with the introduction of HP/UX 10 or so. Loads of files moved, which was a code-breaking issue, particularly for some of the middleware we were using at the time.
As for AIX, again, early versions of AIX were based on SysVR3, and AIX 3.1 and later were based on - ta-daaaa - SysVR4. Maybe you should try grepping Caldera's complaints and discovery requests for 'AIX'.
Irix, BTW, got SysVR4 in 1991.
I'm sure you can find some emails from 1927 "disproving" my actual real world experience, though.
* The beauty of *n*x systems is that you almost always** don't care what actual kernel is running under your code. But I thought it was SysVR4 that brought shared library support around 1990 or so. Not a code breaking issue, but we had to rejig build systems.
** About the only major issue I hit that involved much more than a recompile was Sun's decision to go from their own threading mechanism to pthreads. That one hurt.