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Document Type Definitions (DTD)

A DTD in an XML document provides a list of the elements, attributes, comments, notes, and entities contained in the document. It also indicates their relationship to one another within the document. In other words, a DTD is the grammar of an XML document[12].

There are thousands of DTDs out there to choose from. Most of them are related to a specific industry or enterprise. Unless you have unlimited time and capital, there is probably no reason to even contemplate making a custom DTD that models your core organizational elements. The most widely distributed DTD is DocBook[10], which was originally developed for documenting computer software. Many popular DTDs, such as the Telecom Interchange Markup (TIM) are derivatives of DocBook. Because XML is extensible, you can begin with a DTD that meets your core requirements and then make minor modifications and additions to it at a later date without invalidating all your XML.

The DTD defines the taxonomy that you will use to parse information about the subject matter into re-usable form[4].


next up previous index
Next: XSL and XSLT Up: XML Basics Previous: XML Basics   Index
root 2003-07-21