When you generate a report, you typically select a Business Intelligence and Reporting Tools (BIRT) report design, which has the file name extension RPTDESIGN. Alternatively, you can select an Extensible Stylesheet Language Transformation (XSLT) report template.
You can use the reporting feature to create report designs, but you can generate a report without knowing how to design them. For information about designing reports, see the topic "Creating report designs."