Where would you like to go tomorrow?™
The HTML composite DTD is Copyleft
1996 by Silmaril Consultants and is protected by the terms of the GNU General Public License, a copy of which is included in the distribution of this software as file gnugpl.html. You may freely distribute and use this material, provided that nothing is done to prevent its further distribution or use. It may not be distributed without a similar condition, including this condition, being imposed on the subsequent user. Modifications should be reported to the author.
This documents version 0.8
The first HTML Document Type Description was devised to support the original versions of World-Wide Web software in the early 1990s. A revised and more widely-debated version was codified as HTML 2.0 by the Internet Engineering Task Force (IETF)'s Working Group on HTML, and adopted by them as a draft standard, RFC1866, in November 1995.
A more advanced but experimental version, HTML+ (now obsolete), had been under discussion for several years, and many of its features were republished as HTML3 in an Internet Draft (March 1995). On expiry, this draft was taken back into consideration by the World-Wide Web Consortium (W3C), which had in the meantime succeeded the IETF as principal motive force in HTML development.
The W3C has attempted to reconcile the sometimes conflicting aspirations of some of its members by publishing two experimental versions, HTML 3.2 (largely HTML 2.0 with the addition of stylesheet and scripting support), and Cougar (a less structured version of HTML3) in May and July 1996 respectively.
Companies implementing Web software, particularly browsers,
and individuals implementing HTML pages have throughout this period
continually sought additional markup facilities for their own
purposes. In some cases element names were simply invented on an
The edition of HTML included here, codenamed Aardvark, is a composite of all known versions, containing all the elements published in the various forms of HTML in the last five years, in a manner which can be used by editors, browsers, parsers, databases, search engines, formatters, and any other conforming application of ISO 8879 - Standard Generalized Markup Language (SGML, the language in which HTMLis written).
The versions of HTML included in this edition were taken from public copies of DTDs and fragments on the Web:
My thanks to all the many authors and contributors to these DTDs, whose notes and comments have made it easier to work out what to do.
The current version of this DTD is 0.8, and it is released for comment conducted on the www-html@w3.org mailing list by the relevant interested parties.
Very few changes to structure have been made, although those familiar with the internals of previous versions will notice the large amount of additional material from the other versions.
The major change is to the way in which content models are
used. The established mechanism was for
There are now four classes of elements, defined by the parameter entities following:
Parameter entity |
Elements represented |
---|---|
Elements which are generally used to contain the continuous text of the document. |
|
Elements which usually contain special-purpose material, or no text material at all. |
|
Elements which directly hold text |
Descriptive or analytic markup:
Visual
markup: Hypertext and graphics:
Mathematical:
Documentary: |
Mathematical content |
The most significant distinction is that the insertions class can be peer with text as well as with structure, whereas text can nest only within structure.
Some changes have been made to the content models of the
text elements to accommodate this, but the most
noticeable are
The exclusion exceptions for
The infamous problem of mixed content in list items has been tackled head on by simply permitting it: text data is allowed as well as paragraph-level markup. This may cause some less well-endowed editors a little grief, but the advantages of being able to tweak the performance characteristics of various browsers are too great to pass up.
The ICADD fixed attributes which were added by the late and very much missed Yuri Rubinsky have been reinserted for those elements to which they were attached in RFC1866.
The astute reader will have noted the new elements
There is one new attribute,
The HTML3 concept of HTML-specific character entity files has been ditched, and this version includes the whole of ISOlat1, ISOlat2, ISOnum, ISOpub and ISOtech. This should have been done years ago, but browser authors are understandably wary of the font problems involved.
The machine-generated status of the DTD file means that there
was a substantial amount of legacy comment from the assorted versions
used in compositing the DTD. The majority of this has been edited out
so that irrelevant and obsolete parameter entities are not left to
confuse the unwary reader, but users who locate undetected
The elements for which no ICADD fixed attribute exists need analysing and the relevant values adding from the International Committee for Accessible Document Design DTD ("-//EC-USA-CDA/ICADD//DTD ICADD22//EN").
There are undoubtedly errors, both of omission and of comission, and I would be very grateful for details.
Peter Flynn