The XHTML 1.0 standard is formally defined as three Extensible Markup Language (XML) Document Type Definitions (DTDs): the Strict DTD, the Transitional DTD, and the Frameset DTD. These DTDs correspond to the respective HTML 4.01 DTDs, defining the same elements and attributes using XML rather than the Standard Generalized Markup Language (SGML) as the DTD authoring language.
The Strict DTD defines only those elements that are not deprecated
in the HTML 4.01 standard. Ideally, everyone would create XHTML documents
that conform to the Strict DTD. The Transitional DTD includes all those
deprecated elements and more accurately reflects the HTML in use today,
with many older elements still in common use. The Frameset DTD is
identical to the Transitional DTD, with the exception that the document
<body> is replaced by the
Since the HTML Transitional DTD is the one upon which this book is based, it is only appropriate that we include the corresponding XHTML DTD. Note that we have reprinted this DTD verbatim and have not attempted to add extensions to it. Where our description and the DTD deviate, assume the DTD is correct:
<!-- Extensible HTML version 1.0 Transitional DTD This is the same as HTML 4.0 Transitional except for changes due to the differences between XML and SGML. Namespace = http://www.w3.org/1999/xhtml For further information, see: http://www.w3.org/TR/xhtml1 Copyright (c) 1998-2000 W3C (MIT, INRIA, Keio), All Rights Reserved. ...