 the fitted
function over the range of the X errors, rather than taking the central value by adding
an <tt>Integrate(true)</tt> argument to <tt>chi2FitTo()</tt>

<p>Two new arguments, <tt>StoreError(const RooArgSet&)</tt> and <tt>StoreAsymError(const RooArgSet&)</tt>
have been added to the <tt>RooDataSet</tt> constructor to simplify the process of storing the errors
of X and Y variables along with their values in a dataset.

<p>The newly added tutorial macro <tt>rf609_xychi2fit.C</tt> illustrates the use of