\subsubsection{The Z mass and width}

The Z mass was determined at LEP from the line shape scan to be  $91187.5 \pm 2.1$~MeV. The statistical error of 1.2~MeV would be reduced below 5 keV at TLEP. The systematic uncertainty was dominated by the error pertaining to the beam energy calibration (1.7~MeV). As seen in Section~\ref{sec:exp}, a continuous measurement with resonant depolarization of single bunches should allow a reduction of this uncertainty to well below 100 keV. Other errors include the theoretical uncertainties in the calculation of initial state radiation ($\le 100$~keV), in the production of additional lepton pairs ($\le 300$~keV), and in the theoretical line-shape parametrization ($\le 100$~keV). It is clear that revisiting the QED corrections will be a high priority item when embarking in a new program of precision measurements at TLEP. \\
\textbf{\textit{An overall uncertainty of 100~keV or better is therefore a reasonable target for the Z mass precision at TLEP}}.

The Z width was also determined from the line shape scan at LEP to be  $2495.2 \pm 2.3$ MeV. The statistical error of 2 MeV would be reduced to less than 10 keV at TLEP. The systematic uncertainty from the LEP energy calibration was 1.2 MeV, clearly dominated by the reproducibility issues of the beam energy calibration. Again, this uncertainty is expected be reduced to below 100 keV at TLEP. 
The theory systematic uncertainties on $\Gamma_{\rm Z}$ were estimated at the level of 200 keV and should be revisited.\\
\textbf{\textit{An overall uncertainty of 100 keV or better is a reasonable target for the Z width precision at TLEP}}.
  

