_POSIX_CHOWN_RESTRICTED	_PC_CHOWN_RESTRICTED
_POSIX_NO_TRUNC	_PC_NO_TRUNC
_POSIX_VDISABLE	_PC_VDISABLE
POSIX_ASYNC_IO	_PC_ASYNC_IO
POSIX_PRIO_IO	_PC_PRIO_IO
POSIX_SYNC_IO	_PC_SYNC_IO