Many documents on the Web use non-standard elements such as EMBED and non-standard attributes such as the LEFTMARGIN attribute on the BODY element. These documents will not validate against standards like HTML 3.2 or HTML 4.0, but validation is too important a tool to be ignored for this reason.

List of valid DTDs you can use in your document.

List of J2EE DTDs

The purpose of a Document Type Definition is to define the legal building blocks of an XML document. It defines the document structure with a list of legal elements.

DTD parsers for Java seem to be pretty scarce. That's probably because DTD isn't valid XML. At some point, if/when XML Schema becomes widely accepted, no one will need DTD parsers anymore. Until then, you can use this library to parse a DTD.

DTD is described in XML 1.0 standard. In this tutorial basic DTD features are demonstrated on many examples.

This report describes the XML specification ("XMLspec") DTD used for World Wide Web Consortium (W3C) specifications and notes related to XML. It is maintained by Eve Maler (, +1 781 442 3190) of Sun Microsystems. This release of the report corresponds to the DTD with the formal public identifier "-//W3C//DTD Specification Version 2.1//EN".

The National Center for Biotechnology Information (NCBI) of the National Library of Medicine (NLM) created the Journal Archiving and Interchange Document Type Definition (DTD) with the intent of providing a common format in which publishers and archives can exchange journal content.