XML DTDLesson 75Free preview

DTD Introduction

This lesson is part of XML · All levels

Summary

Document Type Definition (DTD) is a set of rules that define the elements, attributes, and structure of an XML document. DTDs can be declared directly within a document (internal subset) or stored separately and referenced from outside (external subset). With DTD, an application can validate whether an XML conforms to its structural contract.

Key points

The abbreviation DTD is Document Type Definition
Internal subset is written in <!DOCTYPE root [ ... ]>
External subset is referred to as <!DOCTYPE root SYSTEM "file.dtd">
DTD defines the elements, attributes, and entities that are allowed
Disadvantages: limited data types and no namespace support

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