_XOPEN_SOURCE     229 sys/cdefs.h    #ifdef _XOPEN_SOURCE
_XOPEN_SOURCE     230 sys/cdefs.h    # if (_XOPEN_SOURCE - 0 >= 600)
_XOPEN_SOURCE     234 sys/cdefs.h    # elif (_XOPEN_SOURCE - 0 >= 520)
_XOPEN_SOURCE     238 sys/cdefs.h    # elif (_XOPEN_SOURCE - 0 >= 500)