Headlines and Titles of Works
Q. When referring to a movie or book title while posting to Internet newsgroups, it’s generally impossible to indicate with italics or underscoring. I usually use all upper-case letters (THE LORD OF THE RINGS, FIDDLER ON THE ROOF, for example). What does CMOS suggest?
A. Notwithstanding the tradition among publishers of presenting book titles in full capitals in industry correspondence, interdepartmental memos, and the like—the practice was popular because it saved time on typewriters that required extra keystrokes for underscoring—we recommend avoiding all capitals to express titles that would otherwise be italicized. Instead, use the underscore key (type Shift plus the hyphen key on standard keyboards) when italic type is unavailable:
When I first read _The History of the Siege of Lisbon_, I was so grateful to discover a book about a proofreader that Saramago’s hypnotic stringing together of sentences nearly sent me into an ecstatic trance.
Sometimes asterisks rather than the underscore key are used to express emphasis (e.g., I can’t *stand* one more day of separation from you), but asterisks can be more strictly interpreted as indicating boldface.