pplied efficiently to both <tt>RooDataSet</tt> and <tt>RooDataHist</tt>
At present a single implementation of <tt>RooAbsDataStore</tt> exists,
class <tt>RooTreeDataStore</tt>, that contains the storage implementation
formerly implement in class <tt>RooTreeData</tt>. Methods in class <tt>RooTreeData</tt>
that were not specific to the storage technology have been moved to
class <tt>RooAbsData</tt>.
<br><br>
If your user code only uses the classes <tt>RooDataSet</tt>,<tt>RooDataHist</tt> and <tt>RooAbsData</tt