FailAt sets the return code limit of the current shell script. If
any command returns with a failure code of this value or higher
the script shall abort.
Common failure codes are:
0 - No error
5 - Warning
10 - Error
20 - Failure
The normal value for the return code limit is 10.
If we have a script with the commands
Copy RAM:SomeFile DF0:
and the file RAM:SomeFile does not exist, the Copy command will
Copy: object not found
Copy: returned with error code 20
and the script will abort. However if you include the command
then the script will complete since the return code from Copy is
less than the return code limit.