internal void CopyHeadingAggregates(PivotHeading heading)
 {
     if (heading != null)
     {
         heading.CopySubHeadingAggregates();
         CopyAggregates(heading.Aggregates, m_aggregates);
         CopyAggregates(heading.PostSortAggregates, m_postSortAggregates);
         CopyAggregates(heading.RecursiveAggregates, m_aggregates);
     }
 }