DB_DataObject and the set*(), get*() functions

How is it that these function are working as they do? They aren't defined in either the child or parent classes. In reading the docs, I think I understand correctly that it is being handled by some overloading mechanism (how, exactly?) utilizing the _call() method (is that right?). But in looking at the DB_DataObject's parent class (DB_DataObject_Overload, I think it is? I can't remember off the top of my head), it looks like that class is defining the _call() method but it also looks to be calling itself (ie, this->_call()) in processing the data. Am I reading that wrong? In any case, if someone could explain exactly how the set*() and get*() methods are working when not defined, I would be very appreciative! thnx, Chris