This compute block creates a comment that says "Sales substantially above expectations." for every store where sales exceeded 15% of the sales for all stores. Of course, on the summary row for the report, the value of Pctsum is 100. However, it is inappropriate to flag this row as having exceptional sales. The automatic variable _BREAK_ distinguishes detail rows from summary rows. In a detail row, the value of _BREAK_ is blank. The THEN statement executes only on detail rows where the value of Pctsum exceeds 0.15.
      if sales.pctsum gt .15 and _break_ = ' '
      then comment='Sales substantially above expectations.';
      else comment=' ';