Read the SortOrder property value to determine which sort order is currently applied to the column. Assign a value to this property to sort data by the current column's values. Note that any previous sorting is not cleared when changing the SortOrder property value. The new sort order applies an additional sorting condition to that previously applied. The newly sorted column is added to the sorted columns. Its index within the collection can be obtained using the SortIndex property.
To clear the sorting applied previously, call the control's TreeList.ClearSorting method.
To learn more about sorting, see the Sorting topic.