Conventions This book uses the following typographical conventions:Italics Used for program names, filenames, system names, email addresses, and URLs, and for emphasizing new terms. Constant width Used in examples showing programs, output from programs, the contents of files, or literal information. Constant-width italics Used for general syntax and items that should be replaced in expressions.
 | Indicates a tip, suggestion, or general note. |
|
 | Indicates a warning or caution. |
|
|