| The following is a list of the typographical conventions used in this book: - Italic
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Used to indicate new terms, URLs, filenames, file extensions, and directories and to highlight comments in examples. For example, a path in the filesystem will appear as /Developer/Applications. - Constant width
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Used to show code examples, the contents of files, commands, or the output from commands. Constant width bold -
Used in examples and tables to show commands or other text that should be typed literally. - Constant width italic
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Used in examples and tables to show text that should be replaced with user-supplied values. - Color
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The second color is used to indicate a cross-reference within the text. - RETURN
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A carriage return (RETURN) at the end of a line of code is used to denote an unnatural line break; that is, you should not enter these as two lines of code, but as one continuous line. Multiple lines are used in these cases due to page width constraints. - Menu symbols
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When looking at the menus for any application, you will see some symbols associated with keyboard shortcuts for a particular command. For example, to open an old chat in iChat, you would go to the File menu and select Open . . . (File  Open . . . ), or you could issue the keyboard shortcut,  -O. The symbol corresponds to the key (also known as the "Command" key), located to the left and right of the spacebar on any Macintosh keyboard. You should pay special attention to notes set apart from the text with the following icons:  | This is a tip, suggestion, or general note. It contains useful supplementary information about the topic at hand. |
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 | This is a warning or note of caution. |
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The thermometer icons, found next to each hack, indicate the relative complexity of the hack: |
beginner
moderate
expert