XML TutorialLesson 18Free preview

XML DTD

This lesson is part of XML · All levels

Summary

Document Type Definition (DTD) is a classical scheme that defines the structure of an XML document: which elements may appear, their order, and whether they are mandatory or optional. The DTD may be written internally within the document or externally in a separate file referenced by DOCTYPE. Although simple, DTD does not support the type of integer-class data or date.

Key points

DTD defines elements, attributes, and rules of the XML structure
DTD can be internal (in documents) or external (separate files)
The declaration was written via <!DOCTYPE ...>
Notation #PCDATA marks the text content
DTD does not support numerical and date data types like XSD

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