122. Use the semicolon before the expressions, namely, as, that is, etc., or before their abbreviations, viz., i.e., etc., when they are used to introduce a series of particular terms, simple in form, which are in apposition with a general term.
At present there are four prominent political parties; namely, the Republican, the Democratic, the Prohibition, and the Socialist.
The Colon (:)
123. Use the colon after an introduction to a long or formal quotation, before an enumeration, or after a word, phrase, or sentence that constitutes an introduction to something that follows.
Mr. Royer says in his letter: "You will remember that I promised to send you a copy of my latest musical composition. I am mailing it to you to-day."
There are four essentials of a legal contract: competent parties, consideration, agreement, and legal subject matter.
124. Use the colon after the salutation of a formal letter. (See §161.)
The Dash (—)
125. Use the dash to indicate any sudden break in thought or construction.
I am pleased to meet you, Captain—what did you say your name is?