Rule Definition
The EVALUATE statement allows the implementation of case structures in Cobol. Each case is managed by a WHEN phrase activated by a specific test of a variable. This variable can be the result of a database access, a file record type, the return code of a subprogram or an error code. The WHEN OTHER phrase allows the management of all the cases which have not been taken into account by the previous WHEN phrases. If the variable to be tested contains a new value that is not currently managed then the absence of the WHEN OTHER phrase will lead to a situation in which no process will be performed for this value and the program may have uncontrolled or undefined behavior.

Remediation
Add a WHEN OTHER clause into each EVALUATE statement.

Violation Code Sample

* If WS-STATUS is 3 then there is not action performed
EVALUATE WS-STATUS
  WHEN 1
    MOVE X TO Y
  WHEN 2
    MOVE Z TO Y
END-EVALUATE.

Fixed Code Sample

EVALUATE WS-STATUS
  WHEN 1
    MOVE X TO Y
  WHEN 2
    MOVE Z TO Y
  WHEN OTHER
    PERFORM DISPLAY-ERROR-MESSAGE
END-EVALUATE.