0                  Successful execution. The timeb_t structure is
                       filled in.
    -1                 Indicates an error. Failure might indicate
                       that the system's time-differential factor
                       (that is, the difference between the system
                       time and UTC time) is not set correctly.

                       If the value of the SYS$TIMEZONE_DIFFERENTIAL
                       logical is wrong, the function fails with
                       errno set to EINVAL.