Conventions Used in This Book

Constant width is used for:

Constant width bold is used for:

Constant width italic is used for:

Italic is used for:

Tip

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Warning

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Significant code fragments, complete programs, and documents are generally placed into a separate paragraph, like this:

<?xml version="1.0"?>
<?xml-stylesheet href="person.css" type="text/css"?>
<person>
  Alan Turing
</person>

XML is case-sensitive. The PERSON element is not the same thing as the person or Person element. Case-sensitive languages do not always allow authors to adhere to standard English grammar. It is usually possible to rewrite the sentence so the two do not conflict, and, when possible, we have endeavored to do so. However, on rare occasions when there is simply no way around the problem, we let standard English come up the loser.

Finally, although most of the examples used here are toy examples unlikely to be reused, a few have real value. Please feel free to reuse them or any parts of them in your own code. No special permission is required. As far as we are concerned, they are in the public domain (although the same is definitely not true of the explanatory text).