HTML DTDs (and other public text)

HTML is an application of SGML (Standard Generalized Markup Language), because SGML is an open standard that facilitates structured documents. Unlike LaTeX, troff, or RTF, SGML has no universal "tag set." In stead, each application of SGML defines its own tags in a DTD, or Document Type Definition. An SGML DTD rigoriously specifies the structure of a type of document. For example, the HTML 2.0 DTD specifies that a document has a HEAD and a BODY; the HEAD contains a TITLE, and the BODY contains H1, H2, P, ADDRESS, elements, and so on.

HTML Dialects: Features, Extensions, and DTDs

A number of HTML extensions have been proposed in various HTML discussion forums. Unfortunately, some of them have been deployed without accompanying documentation in the form of a DTD.

DTDs (especially DTD modules, see below) describing those features are solicited. Please send them to www-html, or html-wg.

See also: HTML Specs, Drafts, and Reports

Newest first:

experimental HTML DTD July 96
including style sheets, scripting, the object tag, internationalization and some extensions to forms.
HTML 3.2 May 1996
In pre-release form
Inserting objects into HTML3 Working Draft 22 Apr 96
Dave Raggett et. al.
The HTML3 Table Model W3C Working Draft 23-Jan-96
@@link to DTD
A Modular DTD Approach for HTML Specification In Progress: Jan 19, 1996
Murray Altheim <murray@stonehand.com>
Internationalization of the Hypertext Markup Language Internet Draft 7 Feb 1996
F. Yergeau, G. Nicol, G. Adams, M. Duerst.
Netscape SCRIPT tags Jan 1996?
Netscape Navigator 2.0beta3 adds SCRIPT element and attribute, plus onclick etc. attributes.
A Proposed Extension to HTML : Client-Side Image Maps Internet Draft 01 Dec 1995
James L. Seidman, Spyglass
Form-based File Upload in HTML, Experimental RFC, November 1995
E. Nebel and L. Masinter, Xerox
DTD for Netscape Frames markup In Progress: 20 Sep 1995.
Joe English, Note that this is not a Netscape-supplied document.
Netscape extensions to HTML 3.0
@@Netscape 2.0? extensions: HTML3 tags like BIG, SMALL, plus FONT FACE
Microsoft Internet Explorer 1.0 HTML extensions 1995 (exact date unknown)
@@ Is this documented anywhere? Netscape?
@@Who's is this?
@@ Firstfloor
HTML 2.0 November, 1995 IETF Proposed Standard
This is the public text that appears in RFC1866.
HotJava DTD 24 July 1995
I have taken the HTML 3.0 DTD dated 16 Mar 95 and added the APP element introduced by Sun Microsystems Corp. to accomodate their Java/HotJava WWW application environment.
Revisions made by: Mark Gaither (markg@hal.com)
Original Author: Dave Raggett <dsr@hplb.hpl.hp.com>
Mozilla DTD 27 Oct. 1994
Mark Gaither and Dan Connolly
Netscape EXTENSIONS TO HTML 2.0 1994 (exact date unknown)
These extensions were instruduced in the Netscape 1.1 beta releases.
HTML 3.0 Expired
Mosaic for X version 2.0 Fill-Out Form Support
introduction of FORMS into HTML
new idiom: <A href=xxx><IMG ISMAP></a>
HTML 1.0 DTD March 1993
About HTML
@@ TimBL's original spec. Still available?

What is a DTD good for?

First and foremost, it codifies an agreement among the community about the structure of documents -- in this case, HTML documents.

Additionally, it allows us to:

Aids to Understanding

SGML syntax is somewhat obscure, but at the end of the day, it's pretty similar to a context-free grammar. If you're a programmer, you probably deal with CFGs all the time (you may know them as BNF grammars, or railroad-diagrams, but they're all the same). If you're not a programmer, you deal with CFGs all the time, but it's subconscous! See:

SGML and the Web
especially: Robin Cover's edited collection of SGML materials
@@This is an analysis of the HTML 2.0 DTD maintained by Earl Hood. It does a better job of showing inclusion and exclusion exceptions than the reference above. It's a bit out of date, last I checked.

To compund matters, HTML is evolving continuously. It's a super-human job to keep track of it all. For one pretty good attempt, see:

HTML Reference Manual In progress: 2 January 1996
Michael J. Hannah, Sandia National Laboratories mjhanna@sandia.gov

W3C Logo
Daniel W. Connolly
$Id: Overview.html,v 1.8 1996/12/09 03:28:38 jigsaw Exp $