Find bad data using File-Aid

The Easiest and Coolest way to locate bad data is thru File-Aid's FIND command.

1. OPEN the file in FILE-AID (in either browse or edit mode) 
2. XREF with COPYBOOK. 
3. Use FMT mode. 
4. Then issue the below command. 

F /field-name INVALID
or
F /field-number INVALID

The control will take you to the first invalid data record for the given field.

Example: The FILE has 3 fields namely NAME,AGE,COUNTRY. If you want to find the invalid data in the age field, then issue F /2 INVALID.