Add row
After you select the option, the option is visible in the properties of your ad-hoc analysis toolbar.
After you enable the option, the new row is added to your data as the first row. You can use this new row as an alternative to writeback, to enter or change values. This is particularly useful for long and complex reports.
This could be used if you want to change values for Monaco, for example, and your ad-hoc analysis displays a long list of countries. Instead of searching for Monaco, you can use the option, select Monaco in the first row header that was added, and then change the values.