er
   dimensions the z- or even the y-value may be omitted.
    </li>

    <li>You can also set the number of passed or total events for a bin directly by using the SetPassedEvents or SetTotalEvents method.</li>

    <li>If you already have two histograms filled with the number of passed and total
events, you will use the constructor <a href="http://root.cern.ch/root/html/TEfficiency.html#TEfficiency:TEfficiency%1">TEfficiency(const TH1& passed,const TH1& total)</a>
to construct the TEfficiency object. The 