Advantages of DTDs

• Validation: DTDs allow for the validation of XML documents, ensuring they adhere to a specific structure and set of rules.
• Modularity: Parameter entity references enable modular DTD design, making it easier to maintain and reuse definitions.
• Interoperability: DTDs help establish data exchange standards.
• Documentation: DTDs serve as documentation, providing a clear understanding of the expected XML document structure.

DTD stands for Document Type Definition. It is a set of rules which is used to define the structure and elements of an XML document. A DTD:

• Specifies which elements are allowed in the document
• Order in which they should appear
• Data types for attribute values

DTDs are used to validate and describe the structure of XML documents. In a way, they are a set of rules that confirm that the XML document follows a specified structure.