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At higher centre-of mass energies (240 or 350 GeV, energies,  the beam energy can be determined from the precise knowledge of the Z mass withtwo processes:  (i) the $\epemto {\rm Z}\gamma$ process; and (ii) the $\epemto {\rm ZZ}$ process; making use of the energy-momentum conservation in the kinematic fits. At Whit five years of data taking at $\sqrt{s} = 240$ GeV, these two processes allow the average beam energy (and its spread) with a statistical precision better than 1 MeV. With five years of data taking at  $\sqrt{s} = 350$ GeV, the knowledge of the W mass and the $\epemto {\rm WW}$ production is a tool are tools  of choice for the beam energy measurement determination  in a scan of the $\ttbar$ threshold. threshold, with a similar statistical precision of 1 MeV or better.  With 500 $\infb$, each detector would collect one million gZ events (with Z!e+e,m+m) and 400,000 ZZ events (with none of the two Zs decaying into nn). With techniques similar to those developed to measure the   W mass at LEP2 from WW production, a statistical uncertainty of 5 MeV on the average beam   energy can be obtained with ZZ production for each detector. The measurement of the beam   energy with gZ production was studied in detail Ref. [14]. With one million such events, a   statistical uncertainty of 3 MeV is achievable. A combination of these two measurements per-   formed with four detectors can lead to an ultimate precision of 1 MeV.