A report definition contains data retrieval and layout information for a report. Report Definition Language (RDL) is an XML representation for report definition. The RDL is an open schema; developers can extend RDL with additional attributes and elements. The standard file extension for report definition files is .rdl. Its MIME type is text/xml. An Aspose.Cells template is an Excel workbook that contains the report layout information and it will be saved into RDL Files (Format) after the user has completed the template design work. When user opens an RDL file that does not contain Aspose.Cells template, only its data sources and queries is available for usage in Aspose.Cells.Report.Designer. When a user opens an RDL file that contains Aspose.Cells template, the template will be retrieved first and then opened as an Excel Workbook in MS Excel.