Here are the include/asm-i386 header files, and you can see elf.h, a.out.h, errno.h, ipc.h, all of which SCO claims [PDF] it owns and has never authorized to be used in Linux or under the GPL:

And here's a look inside elf.h, and you might note the reference to SVR4/i386 ABI and dynamic linking:

And streams, another thing SCO is suing about [for anyone new to this, here's more info on Streams, where you will find that SCO said SCO's expert, Thomas Cargill's report found the following: "For example, the Cargill report alleges that IBM has misused the 'totality of the Streams framework', drawing in every line in over 150 new files...." but here it is under the GPL, put there by SCO, as it looks to me]:

And finally, the README file which says that OpenLinux is a Caldera Systems-maintained distribution of Linux, starting with a standard kernel and adding "other unique features":

Is this not utterly ridiculous?