The many different kinds of software discussed in this book made it a real struggle to come up with consistent typographical conventions. Here are the rules I’ve tried to follow:
Used for generic, HTML, SQL, and XML code. Also used for message headers.
Constant Width Bold
Used for user input.
Constant Width Italic
Used for replaceable elements, including markers and abstract markers.
Used for commands, filenames, functions, GUI labels, modules, newgroups, script names, URLs, and URL fragments. Also used to introduce new terms and for emphasis.