The XRSubreport control is used to embed other reports into a report; this allows you to solve the following tasks.
This can be useful if there is a particular report structure that needs to be included in many reports, and if it needs to have a consistent appearance and functionality. A good example is a report header that always contains the same information.
Create side-by-side reports.
By placing two subreports side-by-side, you can create an effective comparison of data coming from two different reports. For more details on this, see Create a Side-by-Side Report.
Create master-detail reports.
Another reason for using subreports is to create master-detail reports (reports with hierarchically linked data). For more details on this, see Create a Master-Detail Report with Subreports.
In the End-User Designer, double clicking a subreport opens its associated report in a new Design Panel tab.