Inheritance with respect to error handling? That will be quite a paper considering inheritance (with encapsulation and polymorphism being the other hallmarks of object-oriented programming) has more to do with data structures as opposed to being used as an error handling mechanism. What properties will the error inherit from a parent error? The fact that it is an error?

Errors - you have Oracle pre-defined, and user defined (error codes in the -20000 to -20999 range and named programmer-defined exceptions). You/Oracle can propagate errors. How do you see an error inheriting properties?