NOT implemented system interfaces from the Single Unix Specification, Volume 4:
aio_cancel
aio_error
aio_fsync
aio_read
aio_return
aio_suspend
aio_write
endnetent
fattach
fmtmsg
getdate
getdate_err
gethostent
getmsg
getnetbyaddr
getnetbyname
getnetent
getpmsg
isastream
lio_listio
mlockall
munlockall
posix_mem_offset
posix_trace[...]
posix_typed_[...]
pthread_mutexattr_getrobust
pthread_mutexattr_setrobust
pthread_mutex_consistent
pthread_mutex_timedlock
pthread_rwlock_timedrdlock
pthread_rwlock_timedwrlock
putmsg
setnetent
sigtimedwait
timer_getoverrun
ulimit
waitid