Usually, you define the scope of a drill-through path to match a parameter that it passes. For example, if a target report contains a list of employees, typically you only want to display the report as an available drill-through choice when a user is viewing employee names in a source report. If employee names are not in the source report and the scope was set on the employee name in the drill-through definition, the employee report does not appear on the list of available drill-through target reports in the Go To page. You can set the scope to a measure or to an item in the report.
In report-based drill-through access, where the drill-through path is associated with a specific report column, the column serves as the scope.