Question about _POSIX2_VERSION value

[Vladimir Zakharov]

Hello

Currently _POSIX2_VERSION is set to 199212L [1]:
$ grep _POSIX2_VERSION /usr/src/include/*.h
/usr/src/include/unistd.h:#define       _POSIX2_VERSION         199212L

Unfortunately, I couldn't find any authoritative open source for
possible _POSIX2_VERSION values. But, for example, GNU diff uses
value 199209 for setting conformity with POSIX 1003.2-1992 standard [2].
Example code from "Advanced Unix Programming" book [3] also uses value
199209.

So shouldn't be _POSIX2_VERSION value changed to 199209L?
Or even to 200112L (almost 14 years have passed from the commit [1])?

1: https://svnweb.freebsd.org/base?view=revision&revision=103929
2: https://www.gnu.org/software/diffutils/manual/html_node/Standards-conformance.html
3: http://basepath.com/aup/ex/ckstdvers_8c-source.html

-- 
Regards,                 | "In theory there is no difference between theory
  Vladimir Zakharov      | and practice. In practice there is."- Yogi Berra