Items appearing in the book are sometimes given a special appearance to set them apart from the regular text. Here's how they look:
Used for citations to books and articles, commands, email addresses, URIs, filenames, emphasized text, and first references to terms.
Used for literals, constant values, code listings, and XML markup.
Constant width italic
Used for replaceable parameter and variable names.
Constant width bold
Used to highlight the portion of a code listing being discussed.
This icon signifies a tip, suggestion, or general note.
This icon indicates a warning or caution.