In addition to naming the report, the RD entry defines the format of each page of the report by specifying the vertical boundaries of the region within which each type of report group can be printed. The RD entry also specifies the control data items. When the report is produced, changes in the values of the control data items cause the detail information of the report to be processed in groups called control groups.
Each report named in the REPORT clause of a file description entry in the file section must be the subject of a RD entry in the report section. Furthermore, each report in the report section must be named in one and only one file description entry.
The report groups that will comprise the report are described following the RD entry. The description of each report group begins with a report group description entry; that is an entry that has a 01 level-number and a TYPE clause. Subordinate to the report group description entry, there can appear group and elementary entries that further describe the characteristics of the report group.