DataGridColumn SortDirection Property
Integer scalar. A zero indicates no sort, a positive value indicates ascending order, a negative value indicates descending order.
The magnitude indicates the sort priority; lower absolute value is higher priority.
For example, if c is an array of of 3 DataColumns, to sort the grid in descending order on the first column, and within that sort in ascendening order by the third column, we would write:
c.SortOrder←¯1 0 2
This property only applies when ReadOnly is 1.