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XML Pocket Consultant
Author William R. Stanek
Pages 416
Disk N/A
Level All Levels
Published 01/16/2002
ISBN 9780735611832
Price $29.99
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Chapter 3: Creating DTDs

Chapter 3  Creating DTDs

In the previous chapter you learned about the basic structures for creating XML documents. As mentioned previously, XML documents can contain many different types of markup, including elements, attributes, and entity references. Whether you generate documents manually in an editor, programmatically in an application, or automatically using a document management system, you'll often need to ensure that documents conform to a specific set of rules. That is, you'll want to ensure that not only are the data structures in the documents formatted correctly, but also that the documents can be understood by the applications that will process them. What you need is a way of expressing the necessary data structures as a set of rules and ensuring conformity. What you need is a custom application of XML. Enter document type definitions (DTDs) and schemas.

Both DTDs and schemas allow you to create XML applications. An XML application defines a custom markup language that describes specific types of data and uses the rules set out in the associated DTD or schema. The DTD/schema rules specify items that are allowed or required in compliant documents. Once you create an XML application using a DTD or schema, you can write documents that conform to your custom markup language. Application software, database systems, and other programs can use the DTD/schema to interpret compliant documents and ensure conformity to the rule set. DTDs are the focus of this chapter. You'll learn more about schemas in Part III, "XML Schemas."


Last Updated: January 17, 2002
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