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COBOL Tutorial

COBOL FIRST Clause

The FIRST clause represents a fundamental page control mechanism within COBOL's Report Writer facility, serving as the primary specification for defining the initial line position where detail content begins on each report page. This clause embodies the principles of structured page layout management by providing precise control over vertical positioning, enabling sophisticated report formatting capabilities, and supporting consistent page structure across multi-page documents while maintaining optimal readability and professional presentation standards in enterprise reporting environments and business documentation systems.

Syntax and Usage

FIRST DETAIL Syntax
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RD report-name
    PAGE LIMIT IS integer LINES
    HEADING integer
    FIRST DETAIL integer
    LAST DETAIL integer
    FOOTING integer.
Report Writer
Page Control
Layout Management

Comprehensive FIRST Implementation

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IDENTIFICATION DIVISION.
PROGRAM-ID. FIRST-CLAUSE-COMPREHENSIVE.
 
ENVIRONMENT DIVISION.
INPUT-OUTPUT SECTION.
FILE-CONTROL.
    SELECT EMPLOYEE-INPUT-FILE
        ASSIGN TO 'EMPLOYEES.DAT'
        ORGANIZATION IS SEQUENTIAL
        ACCESS MODE IS SEQUENTIAL
        FILE STATUS IS INPUT-FILE-STATUS.
    
    SELECT PAYROLL-REPORT-FILE
        ASSIGN TO 'PAYROLL.RPT'
        ORGANIZATION IS SEQUENTIAL
        ACCESS MODE IS SEQUENTIAL
        FILE STATUS IS REPORT-FILE-STATUS.
 
DATA DIVISION.
FILE SECTION.
FD  EMPLOYEE-INPUT-FILE
    BLOCK CONTAINS 0 RECORDS
    RECORD CONTAINS 150 CHARACTERS.
01  EMPLOYEE-INPUT-RECORD.
    05  EMP-ID                  PIC 9(6).
    05  EMP-NAME                PIC X(30).
    05  EMP-DEPARTMENT          PIC X(20).
    05  EMP-POSITION            PIC X(25).
    05  EMP-SALARY              PIC 9(7)V99.
    05  EMP-HIRE-DATE           PIC 9(8).
    05  EMP-STATUS              PIC X(10).
    05  FILLER                  PIC X(40).
 
FD  PAYROLL-REPORT-FILE
    BLOCK CONTAINS 0 RECORDS
    RECORD CONTAINS 132 CHARACTERS.
01  PAYROLL-REPORT-RECORD      PIC X(132).
 
REPORT SECTION.
RD  PAYROLL-REPORT
    CONTROLS ARE FINAL
                 EMP-DEPARTMENT
    PAGE LIMIT IS 66 LINES
    HEADING 1
    FIRST DETAIL 8
    LAST DETAIL 58
    FOOTING 62.
 
*> Report Header with FIRST positioning
01  REPORT-HEADER TYPE IS REPORT HEADING.
    05  LINE NUMBER IS 1.
        10  COLUMN 1            PIC X(25) VALUE 'EMPLOYEE PAYROLL REPORT'.
        10  COLUMN 50           PIC X(10) VALUE 'PAGE'.
        10  COLUMN 61           PIC ZZ9 SOURCE IS PAGE-COUNTER.
        10  COLUMN 70           PIC X(5) VALUE 'DATE:'.
        10  COLUMN 76           PIC X(10) SOURCE IS WS-CURRENT-DATE.
    05  LINE NUMBER IS 2.
        10  COLUMN 1            PIC X(80) VALUE ALL '='.
    05  LINE NUMBER IS 4.
        10  COLUMN 1            PIC X(6) VALUE 'EMP ID'.
        10  COLUMN 10           PIC X(20) VALUE 'EMPLOYEE NAME'.
        10  COLUMN 35           PIC X(15) VALUE 'DEPARTMENT'.
        10  COLUMN 55           PIC X(15) VALUE 'POSITION'.
        10  COLUMN 75           PIC X(10) VALUE 'SALARY'.
        10  COLUMN 90           PIC X(10) VALUE 'HIRE DATE'.
        10  COLUMN 105          PIC X(6) VALUE 'STATUS'.
    05  LINE NUMBER IS 5.
        10  COLUMN 1            PIC X(110) VALUE ALL '-'.
 
*> Detail Line starting at FIRST DETAIL line 8
01  EMPLOYEE-DETAIL TYPE IS DETAIL.
    05  LINE NUMBER IS PLUS 1.
        10  COLUMN 1            PIC 9(6) SOURCE IS EMP-ID.
        10  COLUMN 10           PIC X(20) SOURCE IS EMP-NAME.
        10  COLUMN 35           PIC X(15) SOURCE IS EMP-DEPARTMENT.
        10  COLUMN 55           PIC X(15) SOURCE IS EMP-POSITION.
        10  COLUMN 75           PIC ZZZ,ZZ9.99 SOURCE IS EMP-SALARY.
        10  COLUMN 90           PIC 99/99/9999 SOURCE IS WS-FORMATTED-DATE.
        10  COLUMN 105          PIC X(6) SOURCE IS EMP-STATUS.
 
WORKING-STORAGE SECTION.
01  FILE-STATUS-CODES.
    05  INPUT-FILE-STATUS       PIC XX.
        88  INPUT-SUCCESS       VALUE '00'.
        88  INPUT-EOF           VALUE '10'.
    05  REPORT-FILE-STATUS      PIC XX.
        88  REPORT-SUCCESS      VALUE '00'.
 
01  REPORT-CONTROL-VARIABLES.
    05  WS-CURRENT-DATE         PIC X(10).
    05  WS-FORMATTED-DATE       PIC 99/99/9999.
    05  WS-EMPLOYEE-COUNT       PIC 9(3) VALUE 1.
 
PROCEDURE DIVISION.
MAIN-PROCESSING.
    OPEN OUTPUT EMPLOYEE-INPUT-FILE
    OPEN OUTPUT PAYROLL-REPORT-FILE
    
    INITIATE PAYROLL-REPORT
    
    PERFORM UNTIL INPUT-EOF
        READ EMPLOYEE-INPUT-FILE
            AT END
                CONTINUE
            NOT AT END
                GENERATE EMPLOYEE-DETAIL
        END-READ
    END-PERFORM
    
    TERMINATE PAYROLL-REPORT
    
    CLOSE EMPLOYEE-INPUT-FILE
    CLOSE PAYROLL-REPORT-FILE
    STOP RUN.

Key Features and Benefits

Page Layout Control
  • • Defines starting position for detail lines
  • • Ensures consistent spacing after headers
  • • Controls vertical page utilization
  • • Maintains professional appearance
Report Writer Integration
  • • Works with HEADING clause
  • • Coordinates with LAST DETAIL
  • • Integrates with FOOTING positioning
  • • Supports automatic page breaks

Interactive Tutorial

Hands-On Exercise: Report Layout Design
Practice using FIRST DETAIL for optimal page layout

Exercise 1: Basic Page Layout

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RD CUSTOMER-REPORT
    PAGE LIMIT IS 60 LINES
    HEADING 1
    FIRST DETAIL 6
    LAST DETAIL 52
    FOOTING 56.
 
*> This creates:
*> Lines 1-5: Header area
*> Lines 6-52: Detail area (47 lines available)
*> Lines 53-55: Gap before footer
*> Lines 56-60: Footer area

Exercise 2: Optimized Layout

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RD SALES-REPORT
    PAGE LIMIT IS 66 LINES
    HEADING 1
    FIRST DETAIL 8
    LAST DETAIL 58
    FOOTING 62.
 
*> This provides:
*> Lines 1-7: Extended header area
*> Lines 8-58: Detail area (51 lines available)
*> Lines 59-61: Footer buffer
*> Lines 62-66: Footer area

Best Practices

Knowledge Check

Test Your Understanding

Question 1: Page Layout

If PAGE LIMIT IS 66 LINES, HEADING 1, and FOOTING 62, what's the optimal FIRST DETAIL setting?

Answer: FIRST DETAIL 6 or 8 would be optimal, allowing 4-6 lines for headers and maintaining good spacing before detail content begins.

Question 2: Error Prevention

What happens if FIRST DETAIL is set to line 3 with HEADING 1?

Answer: This creates insufficient space for headers, potentially causing overlapping content or formatting errors. Headers need adequate space before detail lines begin.

Question 3: Best Practice

How do you determine the optimal FIRST DETAIL line number?

Answer: Consider header content (titles, column headers, separators), control break headers, and visual spacing. Allow 2-3 buffer lines after the last header element.

Common Patterns

Standard Business Report
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RD BUSINESS-REPORT
    PAGE LIMIT IS 66 LINES
    HEADING 1
    FIRST DETAIL 8
    LAST DETAIL 58
    FOOTING 62.
 
*> Provides:
*> 7 lines for headers
*> 51 lines for details
*> 4 lines for footers
Compact Report Layout
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RD COMPACT-REPORT
    PAGE LIMIT IS 60 LINES
    HEADING 1
    FIRST DETAIL 6
    LAST DETAIL 54
    FOOTING 58.
 
*> Provides:
*> 5 lines for headers
*> 49 lines for details
*> 3 lines for footers

Frequently Asked Questions

Related Concepts

Report Writer

COBOL Report Writer facility and page control

Page Layout

Report page structure and formatting

Line Positioning

Report line control and spacing management