NOT implemented system interfaces from the Single UNIX® Specification Version 5:

    _Fork
    dcgettext_l
    dcngettext_l
    dgettext_l
    dngettext_l
    endnetent
    fmtmsg
    getdate
    getdate_err
    gethostent
    getnetbyaddr
    getnetbyname
    getnetent
    getresgid
    getresuid
    gettext_l
    mlockall
    munlockall
    ngettext_l
    posix_mem_offset
    posix_typed_mem_get_info
    posix_typed_mem_open
    pthread_mutex_consistent
    pthread_mutexattr_getrobust
    pthread_mutexattr_setrobust
    setnetent
    setresgid
    setresuid
    waitid