Handling conditional errors in PL/I programs.

The authoritative book on PLI you can read it to explore more in writing programs.

PLI Key Phrases

1. ERROR
2. FIXED OVERFLOW
3. OVERFLOW
4. UNDERFLOW
5. ZERODIVIDE
6. ENDFILE
7. UNDEFINED FILE
8. KEY
9. END PAGE

I spent some of my busy schedule time on internet. This is good PDF you can read it.