extensibility

Differences between DTDs and Schemas


XML 1.0 Document Type Definitions (DTDs) provide a particular vocabulary for constructing schemas. Schemas are tools for describing document structures and content. The World Wide Web Consortium (W3C) is currently developing an XML Schema proposal that uses XML document syntax to describe XML document structures. XML Authority uses the term 'schema' to describe both DTDs and the various other schema proposals, including DCD, DDML, SOX, XML-Data, and the schema standards currently under development at the W3C. XML Authority provides a consistent interface you can use when working with any of these schema formats.

More information on each of the newer schema formats is available in their specifications. The list below includes links to the documentation for the format.

In common usage, schemas are still contrasted to DTDs. Typically, schemas are portrayed as the 'next generation' beyond DTDs, although DTDs are really the 'first generation' of schemas. DTDs have much software support in XML 1.0-compliant parsers and applications, while all of the other schema standards are still in development and should only be considered experimental.

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