@niconiconi @crmsnbleyd @pinkforest A quick grep on https://github.com/illumos/illumos-gate makes some Novell copyright notices show up (HAL, Kerberos, …) so at least for illumos I'd be surprised if it wouldn't be clear.

In fact kind of fun to see SGI, Sun, Novell, … in a single notice: https://github.com/illumos/illumos-gate/blob/master/usr/src/lib/libdwarf/common/dwarf_elf_access.c

And an interesting one is seeing a lot of files with just Sun followed by AT&T, makes me wonder if Sun passed a deal with AT&T directly. At least I'm not seeing any Santa Cruz / SCO copyright notices, just things like documentation and USB/PCI IDs.
And Caldera only shows up in an antique Grub module of all the things: https://github.com/illumos/illumos-gate/blob/master/usr/src/grub/grub-0.97/netboot/tlan.c