_XOPEN_SOURCE_EXTENDED
defined(_XOPEN_SOURCE) && _XOPEN_SOURCE_EXTENDED - 0 == 1
#if defined(__hpux) && defined(_XOPEN_SOURCE_EXTENDED)
#ifndef _XOPEN_SOURCE_EXTENDED
#elif (defined(_XOPEN_SOURCE) && _XOPEN_SOURCE_EXTENDED - 0 == 1)
(_XOPEN_VERSION - 0 < 4) && !defined(_XOPEN_SOURCE_EXTENDED)