The Subreport control is a placeholder for data from a separate report. In ActiveReports, for better performance, we recommend using data regions instead of Subreport controls wherever possible. The reason is that the report server must process every instance of each subreport, which can become burdensome in very large reports with a large number of subreports processed many times per report. Using data regions to display separate groups of data can be much more efficient in such reports. For more information, see Report Controls.
You can also pass parameters to the subreport from the main report so that data related to the main report displays in each instance of the subreport.
Subreports make sense when you need to nest groups of data from different data sources within a single data region, or when you can reuse a subreport in a number of reports. Here are some things to keep in mind while designing subreports.
With the control selected on the report, in the Commands section at the bottom of the Properties window, you can click the Property dialog command to open the dialog.