AccdDelayVariance is also modified by each intervening ST
agent as a measure, in milliseconds squared, of the
packet dispersion. This quantity can be used by the
target or origin in determining whether the resulting
stream has an adequate quality of service to support the
application. Note that it is implicitly assumed that the
requested delay variance is zero and there is no limit on
the delay variance, so there are no parameters to specify
these explicitly.