The following conditions are useful in testing and debugging your programs:
Running your program with these conditions decreases performance, but ON-units for these conditions can serve as powerful tools for finding out the sources of errors in your program. You can enable any of these conditions by writing an ON-unit for them. Then, if the condition is raised, your ON-unit can define an action that tells you the cause of the error.
For example, if your program raises FIXEDOVERFLOW, it is useful to issue PUT DATA to discover the values of your data that led to the condition being raised.
In addition, the PREFIX option is useful because you can enable conditions without having to edit your program.