The ELF format isn't the one that I'm the most concerned about, but for example compressed sections were updated in the past decade. The ABI for x86-64 is out-of-date (actually, the site it links to is now a 404, but my recollection was that was a version around 2013)--missing things like _Float16 rules, DWARF register naming for AMX and APX registers, microarchitecture levels, new relocation types,
I'm aware of that (and peeved that they've got runners set up for the x86-64 ABI but not the i386 ABI, so there's no nice PDF version of the i386 version I can use).
