I did a spot check while writing the DwarfExtensions page:
https://fedorahosted.org/elfutils/wiki/DwarfExtensions
Incidentally, when I looked before some of the "DWARF5 proposal" and
such links were broken. I don't recall which ones. So you should
check on those.
Some extensions have "normal" names that don't
immediately show they
are extensions - one is even a suggestion for DWARF5 so even their
constant values are not in the vendor space.
We certainly don't want to put anything into dwarf.h that isn't
actually in DWARF4, except for proper extensions that use a proper
name prefix and the proper part of the value space.
Thanks,
Roland