Measurement of the Mass and Width of the W boson                               
  
        The mass and width of the W boson are measured using the Opal          
        detector at LEP. Results are obtained from approximately               
        500 pb-1 of data recorded at centre-of-mass energies of between        
        161-202 GeV.                                                           
  
 Parallel session :5                   
 Plenary  session :6a