DTD

The Document Type Definition (DTD) is used to validate an SGML or XML document.

DTDs are used to support and effectively describe XML file structures, providing the vocabulary and allowable structure of the elements in an XML document.

A DTD defines a Content Model.

In SGML or XML, the DTA is a formal description of the components of a specific document or class of documents. DTDs provide a formal grammar used for machine processing (parsing) of documents expressed in SGML or XML.

A DTD description includes:

• The containers or elements that make up the document; e.g., paragraphs, headings, list items, figures, tables, etc.
• The logical structure of the document; e.g., chapters containing sections, etc.
• Additional information associated with elements (known as Attributes); e.g., identifiers, date stamps, etc.

DTD is now generally superseded by the XML Schema Document (XSD), which is essentially a DTD written in XML.

Up to Glossary of Terms