The Subtotals option on the
Layout for Column form can be
Off or set to the number of a sorted column. Subtotals can only be produced for columns containing numeric data.
Set Subtotalling on for the Centre Line Length column, and the report will look like this:
The result of the expression (entered in the Expression text box on the
Creating Column form) will be shown for every line in the report. This is the normal setting for reports without sorting or totalling.