NOT implemented system interfaces from the Single Unix Specification, Volume 4:

    acoshl
    acosl
    aio_cancel
    aio_error
    aio_fsync
    aio_read
    aio_return
    aio_suspend
    aio_write
    asinhl
    asinl
    atan2l
    atanhl
    atanl
    cabsl
    cacoshl
    cacosl
    cargl
    casinl
    catanhl
    catanl
    cbrtl
    ccoshl
    ccosl
    ceill
    cexpl
    cimagl
    clogl
    conjl
    copysignl
    coshl
    cosl
    cpowl
    cprojl
    creall
    csinhl
    csinl
    csqrtl
    ctanhl
    ctanl
    duplocale
    endnetent
    erfcl
    erfl
    exp2l
    expl
    expm1l
    fabsl
    fattach
    fdiml
    floorl
    fmal
    fmaxl
    fminl
    fmodl
    fmtmsg
    freelocale
    frexpl
    getdate
    getdate_err
    gethostent
    getmsg
    getnetbyaddr
    getnetbyname
    getnetent
    getpmsg
    hypotl
    ilogbl
    isalnum_l
    isalpha_l
    isastream
    isblank_l
    iscntrl_l
    isdigit_l
    isgraph_l
    islower_l
    isprint_l
    ispunct_l
    isspace_l
    isupper_l
    iswalnum_l
    iswalpha_l
    iswblank_l
    iswcntrl_l
    iswdigit_l
    iswgraph_l
    iswlower_l
    iswprint_l
    iswpunct_l
    iswspace_l
    iswupper_l
    iswxdigit_l
    isxdigit_l
    ldexpl
    lgammal
    lio_listio
    llroundl
    log10l
    log1pl
    log2l
    logbl
    logl
    lroundl
    mlockall
    modfl
    munlockall
    nanl
    nearbyintl
    newlocale
    nextafterl
    nexttoward
    nexttowardf
    nexttowardl
    posix_mem_offset
    posix_trace[...]
    posix_typed_[...]
    powl
    pthread_barrier[...]
    pthread_mutexattr_getrobust
    pthread_mutexattr_setrobust
    pthread_mutex_consistent
    pthread_mutex_timedlock
    pthread_rwlock_timedrdlock
    pthread_rwlock_timedwrlock
    putmsg
    reminderl
    remquol
    roundl
    scalblnl
    scalbnl
    setnetent
    sigaltstack
    sigtimedwait
    sinhl
    sinl
    sockatmark
    sqrtl
    strcasecmp_l
    strcoll_l
    strfmon_l
    strncasecmp_l
    strtold
    strxfrm_l
    tanhl
    tanl
    tcgetsid
    tgammal
    timer_getoverrun
    tolower_l
    toupper_l
    towctrans_l
    truncl
    ulimit
    uselocale
    waitid
    wcscasecmp_l
    wcsncasecmp_l
    wcstold
    wcsxfrm_l
    wctrans_l
    wctype_l