Editing COBOL (section)

====Scope termination====
Some statements, such as {{code|IF}} and {{code|READ}}, may themselves contain statements. Such statements may be terminated in two ways: by a period (''{{dfn|implicit termination}}''), which terminates ''all'' unterminated statements contained, or by a scope terminator, which terminates the nearest matching open statement.

<syntaxhighlight lang="cobolfree">
*> Terminator period ("implicit termination")
IF invalid-record
    IF no-more-records
        NEXT SENTENCE
    ELSE
        READ record-file
            AT END SET no-more-records TO TRUE.

*> Scope terminators ("explicit termination")
IF invalid-record
    IF no-more-records
        CONTINUE
    ELSE
        READ record-file
            AT END SET no-more-records TO TRUE
        END-READ
    END-IF
END-IF
</syntaxhighlight>

Nested statements terminated with a period are a common source of bugs.{{sfn|ISO/IEC JTC 1/SC 22/WG 4|2014|p=899}}{{sfn|McCracken|Golden|1988|loc=§ 8.4}} For example, examine the following code:

<syntaxhighlight lang="cobolfree">
IF x
    DISPLAY y.
    DISPLAY z.
</syntaxhighlight>

Here, the intent is to display <code>y</code> and <code>z</code> if condition <code>x</code> is true. However, <code>z</code> will be displayed whatever the value of <code>x</code> because the <code>IF</code> statement is terminated by an erroneous period after {{code|DISPLAY y|lang=cobolfree}}.

Another bug is a result of the [[dangling else problem]], when two <code>IF</code> statements can associate with an <code>ELSE</code>.

<syntaxhighlight lang="cobolfree">
IF x
    IF y
        DISPLAY a
ELSE
    DISPLAY b.
</syntaxhighlight>

In the above fragment, the <code>ELSE</code> associates with the &nbsp;{{code|IF y|lang=cobolfree}}&nbsp; statement instead of the &nbsp;{{code|IF x|lang=cobolfree}}&nbsp; statement, causing a bug. Prior to the introduction of explicit scope terminators, preventing it would require &nbsp;{{code|ELSE NEXT SENTENCE|lang=cobolfree}}&nbsp; to be placed after the inner <code>IF</code>.{{sfn|McCracken|Golden|1988|loc=§ 8.4}}