XML Schemas Compared to DTDs
As we saw in Chapter 4, “Structuring XML Documents with DTDs,” Document Type Definitions can either be internal or external sets of declarations and definitions that describe the XML document structure.
Document Type Definitions are a holdover from the days of SGML. However, DTDs when used with XML are more limited in what can be accomplished than with SGML. DTDs basically provide a mechanism for specifying elements, attributes, entities, and notations. Now, that does not mean that DTDs are not useful. In fact, there are many applications of XML in which DTDs are exceptionally powerful.
But there are many applications in which DTDs fall short, and many users find that authoring XML Schemas is simpler than authoring ...
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