NOT implemented system interfaces from the Single Unix Specification, Volume 3:

    acoshl
    acosl
    aio_cancel
    aio_error
    aio_fsync
    aio_read
    aio_return
    aio_suspend
    aio_write
    asinhl
    asinl
    atan2l
    atanhl
    atanl
    bsd_signal
    cabsl
    cacos
    cacosf
    cacosh
    cacoshf
    cacoshl
    cacosl
    carg
    cargf
    cargl
    casin
    casinf
    casinh
    casinhf
    casinhl
    casinl
    catan
    catanf
    catanh
    catanhf
    catanhl
    catanl
    cbrtl
    ccos
    ccosf
    ccosh
    ccoshf
    ccoshl
    ccosl
    ceill
    cexp
    cexpf
    cexpl
    cimag
    cimagf
    cimagl
    clock_getcpuclockid
    clog
    clogf
    clogl
    conj
    conjf
    conjl
    copysignl
    coshl
    cosl
    cpow
    cpowf
    cpowl
    cproj
    cprojf
    cprojl
    creal
    crealf
    creall
    csin
    csinf
    csinh
    csinhf
    csinhl
    csinl
    csqrt
    csqrtf
    csqrtl
    ctan
    ctanf
    ctanh
    ctanhf
    ctanhl
    ctanl
    endnetent
    erfcl
    erfl
    exp2l
    expl
    expm1l
    fabsl
    fattach
    fdiml
    feclearexcept
    fegetenv
    fegetexceptflag
    fegetround
    feholdexcept
    feraiseexcept
    fesetenv
    fesetexceptflag
    fesetround
    fetestexcept
    feupdateenv
    fgetwc
    fgetws
    floorl
    fmal
    fmaxl
    fminl
    fmodl
    fmtmsg
    fputwc
    fputws
    frexpl
    fwide
    fwprintf
    fwscanf
    getcontext
    getdate
    getdate_err
    gethostent
    getmsg
    getnetbyaddr
    getnetbyname
    getnetent
    getpmsg
    getwc
    getwchar
    hypotl
    ilogbl
    initstate
    isastream
    ldexpl
    lgammal
    lio_listio
    llround
    llroundf
    llroundl
    log10l
    log1pl
    log2l
    logbl
    logl
    lroundl
    makecontext
    mlockall
    modfl
    munlockall
    nanl
    nearbyintl
    nextafterl
    nexttowardl
    posix_mem_offset
    posix_spawn[...]
    posix_trace[...]
    posix_typed_[...]
    powl
    pthread_attr_getguardsize
    pthread_attr_getstack
    pthread_attr_getstackaddr
    pthread_attr_setguardsize
    pthread_attr_setstack
    pthread_attr_setstackaddr
    pthread_barrier[...]
    pthread_condattr_getclock
    pthread_condattr_setclock
    pthread_getcpuclockid
    pthread_mutex_timedlock
    pthread_rwlock_timedrdlock
    pthread_rwlock_timedwrlock
    pthread_setschedprio
    pthread_spin_[...]
    putmsg
    reminderl
    remquol
    roundl
    scalblnl
    scalbnl
    setcontext
    setnetent
    sigaltstack
    sigtimedwait
    sinhl
    sinl
    sockatmark
    sqrtl
    strfmon
    strtold
    swabcontext
    swprintf
    swscanf
    tanhl
    tanl
    tcgetsid
    tgammal
    timer_getoverrun
    truncl
    ulimit
    vfwprintf
    vfwscanf
    vswprintf
    vswscanf
    vwprintf
    vwscanf
    waitid
    wcsftime
    wcstod
    wcstof
    wcstoimax
    wcstok
    wcstold
    wcstoumax
    wcswcs
    wordexp
    wordfree
    wscanf