Report Writer Basics

Report Writer is an optional COBOL feature that lets a programmer describe the desired layout of a printed report declaratively, in the REPORT SECTION of the DATA DIVISION, instead of writing procedural logic to track line counts, page breaks, and control totals by hand. The RD (Report Description) entry links a report to an output file declared with REPORT IS in the FD, and beneath it, 01-level report group entries describe headings, detail lines, and footings using clauses like TYPE IS PAGE HEADING, TYPE IS DETAIL, and TYPE IS CONTROL FOOTING, with the runtime automatically handling page overflow via LINE-COUNTER and PAGE-COUNTER special registers that the programmer never has to increment manually.

A report is built from named report groups, each an 01-level entry under the RD with a TYPE clause: TYPE IS REPORT HEADING prints once at the very start, TYPE IS PAGE HEADING prints at the top of every page (often via automatic overflow), TYPE IS DETAIL (abbreviated DE) prints one line per data record via the GENERATE statement, TYPE IS CONTROL FOOTING prints subtotal lines whenever a designated control field changes value, and TYPE IS REPORT FOOTING prints once at the very end for grand totals. Individual fields within these groups use LINE NUMBER and COLUMN NUMBER (or PLUS n for relative positioning) to place data precisely, and a SUM clause on a control footing field, such as 05 TOTAL-BY-REGION PIC 9(9)V99 SUM REGION-SALES, tells Report Writer to automatically accumulate and reset the total whenever the control break occurs — no manual ADD or MOVE-to-zero logic required.

Report Writer is driven procedurally by three statements: INITIATE opens the report and resets its internal counters and control fields, GENERATE produces output — either GENERATE detail-name for a specific detail line (which also triggers any due control footings and headings automatically) or GENERATE report-name to force just the control-break logic without a detail line, and TERMINATE closes out the report, firing any final CONTROL FOOTING and the REPORT FOOTING before the underlying file can be closed. Because GENERATE handles page overflow, heading repetition, and control-break totaling internally, the procedural code in a Report Writer program is dramatically shorter than the equivalent hand-coded report logic, though this conciseness comes at the cost of a steep learning curve and reduced flexibility for irregular, non-tabular layouts.