Handling Exceptions

Research has exposed many exceptions to the general rules about addresses. See the "brainstorming" post for some of them.

After considering some options, such as using branching procedures to deal with them, I've decided to focus on the most typical cases. The exceptions can be sprinkled into the content as warnings not to be surprised or lost if you run across them. And to spice the lessons up. Just need to be careful not to confuse the learner with too many or frequent exceptions.