The Drill Down tag is DEPRECATED as of version 13.
The drill-down tag is similar to the link tag. It places a link in the document and requires an EndDrillDown tag for the end of the link. However, it differs in one way and also adds an additional property.
First off, the drill-down tag select points to a template file, the template for the report to generate when the drill-down is clicked. This filename must be a valid URL (file, http, etc). It cannot be a select against the data source. However, it still needs to have a data source assigned so that the tag is processed with the other tags in that data source (primarily to assign the drill-down variables).