code: function _fnSortingClasses( settings )
  	{
  		var oldSort = settings.aLastSort;
  		var sortClass = settings.oClasses.sSortColumn;
  		var sort = _fnSortFlatten( settings );
  		var features = settings.oFeatures;
  		var i, ien, colIdx;
  	
  		if ( features.bSort && features.bSortClasses ) {
  			// Remove old sorting classes
  			for ( i=0, ien=oldSort.length ; i<ien ; i++ ) {
  				colIdx = oldSort[i].src;
  	
  				// Remove column sorting
  				$( _pluck( settings.aoData, 'anCells', colIdx ) )
  					.removeClass( sortClass + (i<2 ? i+1 : 3) );
  			}
  	
  			// Add new column sorting
  			for ( i=0, ien=sort.length ; i<ien ; i++ ) {
  				colIdx = sort[i].src;
  	
  				$( _pluck( settings.aoData, 'anCells', colIdx ) )
  					.addClass( sortClass + (i<2 ? i+1 : 3) );
  			}
  		}
  	
  		settings.aLastSort = sort;
  	}
docs: Set the sorting classes on table's body, Note: it is safe to call this function
  when bSort and bSortClasses are false
  @param {object} oSettings dataTables settings object
  @memberof DataTable#oApi