Now that you have had a few weeks to digest the first lesson on semicolons, I'd like to offer you an additional option for using this sometimes maligned mark of punctuation. In the 15th edition of The Chicago Manual of Style (you all have copies on your desk, right?), there are six rules for the use of the semicolon. Here is Rule 6.60:
"In a series. When items in a series involve internal punctuation, they should be separated by semicolons."
Perhaps that rule isn't very clear. Let me try to explain just what it means. Have you ever been confused when reading a list? I would bet that the reason for confusion is because the writer included supplemental information in the list. What do I mean? It's easier to give examples than to explain.
Here is an example of a sentence that includes a confusing list:
Representing the United States are Joe Biden, Vice President, John Kerry, Secretary of State, Leon Panetta, Secretary of Defense, and Arne Duncan, Secretary of Education.
Mind you, the above sentence is grammatically correct. You certainly may use commas to separate the items in the list and their titles, but when you read the list, you have to wonder just how many people are in attendance. To make this list easier to follow, use a colon AFTER the descriptor. I've underlined the semicolons to make them stand out.
Representing the United States are Joe Biden, Vice President; John Kerry, Secretary of State; Leon Panetta, Secretary of Defense; and Arne Duncan, Secretary of Education.
Here is another example of using a semicolon in a series:
The trip includes stops in Dublin, Ireland; London, England; Paris, France; Rome, Italy; and Athens, Greece.
Another advantage of using the semicolon in this example is that it forces the writer to keep the list parallel. Notice that each item gives the name of city followed by the country rather than a hodgepodge of cities and countries. The reader knows exactly what the trip includes.
By using a different (and stronger) mark of punctuation to separate the items in a list, it is easier for the reader to grasp what you are trying to communicate. While it's easy to forget sometimes, our job as writers is to make our meaning clear. Punctuation is designed to help. If it doesn't help, then we need to either use punctuation differently or rewrite the sentence to make the meaning clear.