The SubTotal When Value Changes option displays a Sort by Sub Totals line, with the current Sort By subtotal value, when the value of the current Sort By field changes.
When SubTotal When Value Changes is enabled and the Sort By option is set to something other than None, the Sort By SubTotal line is displayed with the current Sort By subtotal value.
When SubTotal When Value Changes is disabled, the Sort By SubTotal line is not displayed.
Note: If SubTotal When Value Changes is enabled, the Separate w/ Page Breaks parameter starts a new page after the sub-total prints.
See:
Report Manager Contents