88 Condition name in COBOL acts like a Two-Way switch

COBOL allows conditions to be assigned names. 

Basically, we use Condition-names to indicate when an AT END condition is reached. The syntax of 88 condition name is as follows:

88 condition name VALUE literal

An 88 level entry is usually coded in the WORKING-STORAGE section. The 88 level has only a VALUE clause associated with it. The Values which we provide in the VALUE clause should be of same data type defined in the preceding level. For example,

05 MASTER-FILE-SW     PIC X(1) VALUE 'N'.
      88 EOF-FILE              VALUE 'Y'.

Here, we have defined 88 condition name as an End of File switch for the Master file. Assuming the 88 condition name as a tube light, we've got two ways to switch on the light (to signify the end of file). We can either MOVE 'Y' to MASTER-FILE-SW field or set EOF-FILE condition name to TRUE. The COBOL code will be as follows:

READ MASTER-FILE 
AT END MOVE 'Y' TO MASTER-FILE-SW.

READ MASTER-FILE 
AT END SET EOF-FILE TO TRUE.

Remember, we can't MOVE 'Y' to EOF-FILE. You can only MOVE the value to the data field defined with a PIC clause (MASTER-FILE-SW in this example)  and use the 88 level as a condition. If the MASTER-FILE-SW is equal to 'Y', we call that condition as EOF-FILE.

Examples:

1.

Output:

WS-A BEFORE SET: 
WS-A AFTER SET:A

Remarks: If SW is set to true, then the value of WS-A field will be 'A' else the value will be a space.

2.

Output:
WS-A: S

Remarks: WS-SW is a condition that is met if WS-A field has a value 'S' or 'X' or 'N'. When displaying the field after setting the condition name to TRUE, it shows the first value.

Note: Only level 88 items may have multiple values.

3.

Output:
NOT END OF FILE

Remarks: The 88 condition-name isn't set to TRUE. Hence the output.

Q&A:

Given a scenario like below, which condition name will be set before and after executing the initialize statement? Post your answers in the comments section. 

01 VAR-1     PIC     X(1)     VALUE 'A'.

     88            CHAR       VALUE 'A' THRU 'Z'.

     88            NUMERIC    VALUE '0' THRU '9'.

     88            SPECIAL    VALUE '$','%',' ','&'.

     88            STRING     VALUE '*','#'.

(...)

INITIALIZE VAR-1

That's it! Thanks for reading.

Should you have any questions or suggestions, please let me know through comments.

References:

Structured COBOL programming - 8th edition - STERN / STERN.
COBOL Coding ground by Tutorials point.