_XOPEN_SOURCE
#if defined(_XOPEN_SOURCE_EXTENDED) || (defined(_XOPEN_SOURCE) && (_XOPEN_SOURCE - 0 >= 500))
#ifndef _XOPEN_SOURCE
#if defined(OMITTED__D_XOPEN_SOURCE_600) && !defined(_XOPEN_SOURCE)
#ifdef _XOPEN_SOURCE
# if (_XOPEN_SOURCE - 0 >= 800)
# elif (_XOPEN_SOURCE - 0 >= 700)
# elif (_XOPEN_SOURCE - 0 >= 600)
# elif (_XOPEN_SOURCE - 0 >= 520)
# elif (_XOPEN_SOURCE - 0 >= 500)