  The mass of the $\tau$-lepton has been measured in the decay modes $\tau \to
3\pi \nu_\tau$ and $\tau \to 3\pi \pi^0\nu_\tau$ using a pseudomass technique.
The preliminary result is $1776.71\pm 0.25 {(stat)} \pm 0.62 {(syst)}$ MeV. The
preliminary value of an upper limit on the relative mass difference between
positive and negative $\tau$ leptons is
$|(M_{\tau^+}-M_{\tau^-})|/M_{\mathrm{average}}$ is $5.0 \times 10^{-4}$ at 90%
CL.
