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<a href="profile.html"><img src="dsr-46c.jpg" width="80" height="100"
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<h1>Dave Raggett</h1>

<p>This is my home page where you can learn about my interests,
achievements and how to contact me. Here is my
<a href="cv.html">Curriculum Vitae</a><!-- and <a
href="profile.html">bio</a>--> and my <a
href="http://people.w3.org/~dsr/blog/">blog</a>.</p>

<p><small>W3C staff can access my <a
href="http://www.w3.org/Team/Raggett">work plan and travel
schedule</a>.</small></p>

<p><small><a href=
"http://www.faeriekeeper.net/20041stqtr.htm"><img alt="icon"
src="talkinghands.jpg" border="0" align="middle" width="25"/></a>
Recipient of <a href="http://www.faeriekeeper.net/20041stqtr.htm">
Talking Hands Award</a> in January 2004.</small><br clear="all" />
</p>

<p class="key">[I tend to sign my emails with this <a href="pubkey-20040130.asc">
public key</a>]</p>


<blockquote class="splash"><em>Try out my free Web-based
alternative to Microsoft PowerPoint:
<a href="/Talks/Tools/Slidy">HTML Slidy</a>
and take a look at my <a href="http://www.w3.org/2006/05/Slidy-XTech/slidy-xtech06-dsr.pdf">XTech 2006 paper</a>. See also my cross browser <a
href="http://www.w3.org/2007/03/XForms-Transitional">XForms-Transitional</a>
library for richer forms with less scripting.</em></blockquote>

<p>I am a member of the <a href="http://www.w3.org/People/">W3C Team</a>.
My current roles include: driving W3C work on the relationship
between XBRL and the Semantic Web, research on privacy and identity
management for the EU <a
href="http://www.primelife.eu/">PrimeLife Project</a>, chairing
the <a href="/2005/Incubator/model-based-ui/">W3C Model
Based User Interface Incubator Group</a> and also the <a
href="/2007/uwa/">W3C Ubiquitous Web Applications Working Group</a>.
I am also a member of the <a href="http://www.xbrl.org/StandardsBoard/">XBRL
Standards Board</a>.</p>

<p>I was a W3C Fellow for many years on behalf of a number of
companies, most recently <a href="http://www.justsystems.com">Justsystems</a>,
and before that <a href="http://www.volantis.com">Volantis</a>,
<a href="http://www.canon.com">Canon</a>, <a
href="http://www.openwave.com/">Openwave Systems</a>,
and <a href="http://www.hpl.hp.co.uk/">HP Labs</a> in Bristol, England.
I have been very closely involved with the development of HTML from
the early days (HTML+, HTML 3.0, 3.2, 4.0, XHTML) as well as setting
up the IETF HTTP working group and helping to initiate work on VRML.
I used to be the activity lead for <a href="/MarkUp/">XHTML</a>,
<a href="/MarkUp/Forms/">XForms</a>, <a href="/Math/">MathML</a>, <a
href="/Voice/">Voice Browsers</a> and <a href="/2002/mmi/">Multimodal
Interaction</a>.  I am a visiting professor for the <a
href="http://www.uwe.ac.uk/">University of the West of England</a>.</p>

<p>I have recently become involved in work on <a
title="Extensible Business Reporting Language"
href="http://en.wikipedia.org/wiki/XBRL">XBRL</a>, a markup
standard for financial reports defined by <a
href="http://www.xbrl.org/">XBRL International</a> with the support
of financial institutions around the world. XBRL makes use of XML
Schema, XLink and XML Namespaces to give precise semantics to
financial data. There is a huge potential for combining XBRL
with the Semantic Web as a basis for analysing financial data and
combining it with other sources of information. My starting point
has been to develop an open source tool (<a href="http://xbrlimport.sourceforge.net/">xbrlimport</a>) to translate XBRL into RDF,
and I am looking forward to working with others on realising the
potential. The Semantic Web, with its ability to represent a World
Wide Web of machine interpretable data and metadata, will give users
tremendous flexibility for exploring huge amounts of information
about companies and markets.</p>

<p>I joined the EU <a href="http://www.primelife.eu/">PrimeLife
Project</a> in February 2009 to help with work on privacy enhancing
technologies. The project is funded by the European Commission's 7th
Framework Programme. I am particularly interested with the the
concept of privacy providers as a new class of web services giving
users life long control over their personal data. You get to determine
just how much personally identifying information you disclose to
websites. The approach also offers single-signon and opportunities
for supporting micropayments as value added features for participating
websites.</p>

<p>I have also been working on broadening the Web to include all kinds
of network appliances, whether in the home, office or on the move, and
at the same time reducing the cost and complexities involved in
developing Web applications through declarative languages that enable
higher level authoring tools. The long term aim is to avoid the need for
Web application authors to have to learn the intricacies of markup,
style sheet and scripting languages, and the infuriating variations
across browsers. This will reduce the development and maintenance
costs compared with today's approaches, whilst improving the quality
and the end-user experience on whatever device he or she is using.
I launched the <a href="/2005/Incubator/model-based-ui/">Model
Based User Interface Incubator Group</a> in October 2008 to evaluate
research on model-based user interface design as a framework for
authoring Web applications and with a view to proposing work on
related standards.</p>

<p>My software projects have included <a href="http://xbrlimport.sourceforge.net/">xbrlimport</a>, <a href="#tidy">HTML Tidy</a>,
<a href="#ezmath">EzMath</a>, <a href="/Talks/Tools/Slidy">HTML
Slidy</a>, <a href="/2006/11/XForms-Tiny/">XForms-Tiny</a> and
several experimental browsers. I am currently exploring the potential
of custom XML applications written in <a href="http://haxe.org/">Haxe</a>
and deployed via the extremely ubiquitous flash player. I have
developed components for rendering and for editing SVG that work on
any browser with Flash Player 9 and above. I am utilizing these
components for a Web-based slide editor/viewer named XML Slidy.
The longer term aim is to explore the potential for declarative
models of distributed web applications as part of my work on the
Ubiquitous Web.</p>

<!--
I am now working on
prototyping extensions to browsers on desktops and embedded systems
to support multimodal interaction and device coordination. This is part of
my vision for the Ubiquitous Web which seeks to apply Web technology to
make it much easier to build distributed applications as a synthesis between
the Web and ubiquitous computing. Please visit the <a
href="http://www.w3.org/2006/ubiweb-wiki/W3C_Ubiquitous_Web_Wiki">Ubiquitous
Web Wiki</a>.</p>
-->

<p><a href="http://www.bath-divers.co.uk/"><img src="redsea05.jpg"
align="right" alt="Diving with Alex in the Red Sea 2005"/><img
src="rib.jpg" alt="diving trip" align="right" /></a>In my spare time
I enjoy diving with the <a href="http://www.bath-divers.co.uk/">Bath
Sub-Aqua Club</a>, and recently became an assistant instructor. Here
are my <a href="http://people.w3.org/~dsr/Photos/">collections of
photo's</a> for my recent diving trips to the Scilly Isles, the
southern Red Sea, and to South Africa for tiger sharks and the
famous sardine run. I am married with a son and a daughter, and live
in Bradford on Avon, near Bath in the west of England. Since August
2007 I have been a visiting professor for the University of the West
of England in the Faculty of Environment and Technology. <!--You can find
out more about me in my <a href="profile.html">bio</a>.--> Read about
my interests below:</p>

<p style="clear:both">Recent publications/presentations:</p>

<ul>
<li><a href="http://www.sofsem.cz/sofsem10/presentations/invited/Raggett.pdf">The
Web of Things: Extending the Web into the Real World</a>, January 2010,
an Invited talk at <a href="http://www.sofsem.cz/sofsem10/index.php">SOFSEM
2010</a>, 36th International Conference on Current Trends in Theory
and Practice of Computer Science,  Špindlerův Mlýn, Czech Republic</li>
<li><a href="http://www.w3.org/2008/Talks/0423-dsr-lbs/slides.pdf">Geolocation
on the Mobile Web</a>, 23 April 2008, W3C Track, WWW2008 conference,
Beijing, China</li>
<li><a href="http://http://www.internet-of-things-2008.org//prg/slides/raggett.pdf">Towards
the Web of Things</a>, 27 March 2008, Internet of Things, Zurich, Switzerland.</li>
<li><a href="www.w3.org/2008/Talks/0305-dsr-mw2/slides.pdf">Towards the Web of Things</a>,
Mobile Web 2.0, Seoul, 5 March 2008</li>
<li><a href="http://www.w3.org/2007/Talks/0926-dsr-WDC/slides.pdf">Towards
the Web of Things</a> at <a href="http://www.webdevconf.co.uk/">UWE Web
Developer's Conference</a> in Bristol, UK on 26 September 2007</li>
<li><a href="/2007/03/html-forms/">Google Tech Talk on Forms, 5 March
2007, Mountain View</a></li>
<li><a href="/2006/Talks/0919-dsr-ubiweb/ubiweb.pdf">Ubiquitous
Web presentation</a> on 19 September 2006 at <a
href="http://www.ce2006.org/">CE2006</a>, Antibes, France</li>
<li><a href="http://www.w3.org/2006/05/Slidy-XTech/">Slidy, a web-based
alternative to PowerPoint</a>, XTech on 19 May 2006, Amsterdam</li>
<li><a href="http://www.loquendo.com/en/news/dave_raggett_interview.htm">Interview</a> in the March 2006 edition
of the Loquendo Newsletter</li>
<li><a href="/2006/03/ubiweb-ngw.html">Web Applications and the
Ubiquitous Web</a>, on 13 March 2006 at the <a
href="http://www.webxcon.com/">Next Generation Web Conference</a>,
Seoul, Korea</li>
<li><a href="/2006/03/ubiws-intro.html">Outline</a> on 7 March 2006
to the Japan Members meeting of the <a
href="/2006/02/ubiwebws-agenda.html">W3C Ubiquitous Web workshop</a></li>
<li>My <a href="../../2006/02/woa/">Tech Talk on the Web of Applications</a>
at the Googleplex on 1st February 2006, Google recorded the talk, see the <a
href="http://video.google.com/videoplay?docid=8950294834635667990">video</a></li>
<li><a href="/2006/01/ajax-speech.pdf">Applyng AJAX to add speech
services to Web browsers</a> on 31 January 2006 at <a
href="http://www.avios.com/conference.htm">AVIOS/SpeechTek
West</a></li>
<li>Presentations on <a href="/2005/Talks/0621-dsr-mmi/">MMI Activity</a>
and <a href="/2005/Talks/0621-dsr-ubiweb/">Ubiquitous Web</a> at <a
href="/2005/03/MWeb-seminar.html"><em>Multimodal Web Applications
for Embedded Systems</em></a>, W3C seminar 21 June 2005 - Toulouse, France</li>
<li>Demonstration of a text to speech extension for the Mozilla-Firefox
browser and its application to render RSS to speech at the <a
href="http://www.w3.org/2005/03/02-TechPlenAgenda.html">W3C Technical
Plenary</a>, 2nd March 2005, Boston, MA.</li>
<li>Presentation on the <a href="/2005/02/tp-2005-ubiweb.pdf">Ubiquitous
Web</a> at W3C Technical Plenary, 2nd March 2005, Boston, MA.</li>
<li><a href="css-mmi/">CSS Extensions for Multimodal Interaction</a>,
written together with <a href="/People/maxf/">Max Froumentin</a>,
and introducing the principle of modality independence.</li>
<li>Position paper for the <a href="/2004/09/mwi-workshop-cfp.html">Mobile
Web Initiative Workshop</a>, 18-19th November 2004, Barcelona, Spain:
<a href="/2004/10/mobiweb-ui.html">Winning users over with more attractive
and more flexible mobile web applications</a> [<a href=
"/2004/10/mwi-draggett.pdf">Slides</a>].</li>
</ul>

<h3 align="center"><em>The Ubiquitous Web</em></h3>

<p>The Ubiquitous Web seeks to broaden the capabilities of browsers
to enable new kinds of web applications, particularly those involving
coordination with other devices. These applications involve identifying
resources and managing them within the context of an application session.
The resources can be remote as in a network printer and projector, or
local, as in the estimated battery life, network signal strength, and
audio volume level. The Ubiquitous Web will provide a framework for
exposing device coordination capabilities to Web applications. I organized
and chaired a <a href="/2006/02/ubiwebws-agenda.html">W3C workshop on
the Ubiquitous Web</a> in Tokyo on 9-10 March 2006 as a means to share
use cases, research results, and implementation experience. The workshop
raised a number of security related issues, and the importance of
extending the web application model out into the physical world of
sensors and effectors. In March 2007 I launched and the <a href="/2007/uwa/">Ubiquitous Web Applications working group</a>. I organized
a <a href="http://www.w3.org/2007/02/dmdwa-ws/">Workshop on declarative
models of distributed web applications</a> in June 2007, in Dublin,
Ireland, and plan to hold further workshops on related topics to guide W3C's standards activities in these areas.</p>

<h3 align="center"><em>Voice Browsers</em> and <em>Multimodal
Interaction</em></h3>

<p>I ran a workshop in 1998 to look at the opportunities for W3C to
take a role in extending the Web to support voice interaction as
the means for browsing Web content. This led to the setting up of a
<a href="/Voice/">Voice Browser activity</a> and a working group to
develop related standards. I was the W3C Activity Lead for Voice
Browsers until March 2005. Voice Browsers offer the means to access
Web-based services over any telephone, or for hands &amp; eyes free
operation such as in a car. Voice interaction allows browsers to
shrink in size as you no longer need the physical space for a high
resolution display. The primary initial market is for replacing the
current generation of touch-tone voice menuing systems, so common
these days when you call up companies. Voice Browsers allow you to
use spoken commands rather than having to press "1" for this and "2"
for that etc.</p>

<p>My interest in multimodal interaction started years ago, and led
to work within the Voice Browser activity and more recently to a
new W3C <a href="/2002/mmi/">Multimodal activity</a> of which I am
the W3C Activity Lead. This work is still at an early stage, but aims
to weave together ideas for visual, aural and
tactile interaction with the Web, offering users the means to
choose whether to use their eyes or ears, and fingers or speech as
appropriate to the context in which they find themselves.</p>

<p>Whilst I was working for <a href="http://www.hpl.hp.co.uk/">HP
Labs</a> I developed a voice browser together with a student
(Guillaume Belrose) to test out ideas for using context free
grammars for more flexible voice interaction dialogs. The
applications were written in XML using a language we called <a
href="/Voice/TalkML">TalkML</a>. More recently, I have begun to
study ideas for the use of natural language in multimodal
systems, based upon event driven nested state machines, and inspired
by <a href="http://www.wisdom.weizmann.ac.il/~harel/">David
Harel</a>'s work on State Charts. <a href="/People/maxf/">Max
Froumentin</a> and I, explored this in some ideas for <a
href="css-mmi/">extending CSS to describe interaction</a> based
upon the idea of <em>text as an abstract modality</em>. Whilst
CSS is perhaps easier for authors, an XML based representation
for state machines is likely to provide greater flexibility, and
this is now being pursued within the Voice Browser working group.
I am currently working on developing a means to integrate speech
with web pages via an open source proxy speech server based on
HTTP. This will be usable with any modern web browser without
the need for plugins, and is being developed to enable widespread
experimentation with multimodal web applications.</p>

<!--
<p>Some talks I have presented on voice interaction include:</p>

<ul>
<li>
<p><a href="multimodal-2002Nov.ppt">Multimodal Interaction</a>,
(PowerPoint), MIT Lab for Computer Science, 15th November 2002</p>
</li>

<li>
<p>The Voice area is hotting up, and there are frequent conferences
devoted to it. Here is <a href="/2000/10/VoicePortals/">an
introduction to W3C's work on voice standards</a> I gave to the
Voice Portal conference, held in London on 11th October 2000</p>
</li>

<li>
<p>For a presentation on the Voice Browser Activity, see the <a
href="/Voice/2000/DDay/">Developer's Day talk</a> given on 19th May
2000 in the Mobile track at <a href="http://www9.org/">WWW'9</a>
conference held in Amsterdam, See also <a
href="/2000/Talks/WWW9-Mobile-Web/">Tomorrow's Web</a>, presented
at <a href="http://www9.org/">WWW'9</a> on May 16, and covering the
challenges of dealing with an every increasing range of ways of
accessing the Web.</p>
</li>

<li>
<p>I organized and presented at the <a
href="/2000/09/Papers/Agenda.html">W3C/WAP Workshop on the
Multimodal Web</a>, Hong Kong, 5-6 September 2000.</p>

<p>This workshop addressed the convergence of W3C and WAP
standards, and the emerging importance of speech recognition and
synthesis for the Mobile Web. Read the position papers and summary
of break-out sessions.</p>
</li>

<li style="list-style: none">
<p>See also the talk on <a
href="/Talks/1999/09/15-london-voice/slide1.html">Voice
Browsers</a> as presented to the WAP Forum, in London on 15th
September 1999.</p>
</li>

<li>
<p><a href="http://www.w3.org/Talks/1999/0514-VB-DDay/">Style
sheets for Voice Browsers</a>, as presented at the Developer's Day
at WWW8 in Toronto, on 14th May 1999.</p>
</li>
</ul>
-->

<h3 align="center"><em>Computers with Common Sense</em></h3>

<!-- <h4 class="subtitle">... the next frontier for computing ...</h4> -->

<p>I am intrigued with the idea of giving computers a modicum of
common sense, or in other words a practical knowledge of everyday
things. This would have huge benefits, for instance, much smarter
ways of searching for information, and more flexible user interfaces
to applications. While it might sound easy, this is in fact very
difficult and has defeated traditional approaches based upon
mathematical logic and AI (artificial intelligence). More recently,
work on speech recognition and natural language processing using
statistical methods have shown great promise. Statistical approaches
offer a way out of the combinatorial explosion faced by AI, and I
am excited by work in cognitive science on relevancy theory and the
potential for applying statistical learning techniques to
semantics, learning on the fly or from tagged corpora.</p>

<p>My long term aim is to understand this better and to put it into
practice in the form of a multi-user conversational agent that is
accessible over the Web, so that we can harness the power of the Web
to allow volunteers to teach the system common sense knowledge by
conversing with it in English (and eventually other languages).
I plan to work on an open source broad coverage statistical natural
language processor for parsing and generation, and a relevancy-based
inference system for natural language semantics. Here are <a
href="Sense/">some more details</a>. If you are interested in
collaborating on this, please contact me.</p>

<h3 id="tidy" align="center"><em>Tidying up your markup!</em></h3>

<p><a href="http://www.w3.org/People/Raggett/tidy">"HTML tidy"</a>
is an open source utility for tidying up HTML. Tidy is composed
from an HTML parser and an HTML pretty printer. The parser goes to
considerable lengths to correct common markup errors. It also
provides advice on how to make your pages more accessible to people
with disabilities, and can be used to convert HTML content into XML
as XHTML. Tidy is W3C open source and available free. It has been
successfully compiled on a large number of platforms, and is being
integrated into many HTML authoring tools. Recently the maintenance
of Tidy has been taken over by a group of dedicated volunteers on
SourceForge, see: <a
href="http://tidy.sourceforge.net/">http://tidy.sourceforge.net/</a>.</p>

<h3 align="center"><em>XForms &mdash; the future of Web
forms</em></h3>

<p>A few years ago, I set up a working group that is focusing on
standards for the next generation of Web forms. The key idea is to
separate the user interface and presentation from the underlying
data model and logic. This allows content providers to plug in
different user interfaces as befits different devices, for example,
voice browsers, cell phones, palm-tops, television and desktop
machines. <a href="/MarkUp/Forms">XForms</a> builds on XML to
transfer form data as structured data.</p>

<p>XForms whilst rooted in forms, is also about the common building
blocks for interactive Web applications. The aim is to make it
easier to build powerful Web applications in a world where
increasingly everything will be interconnected. Web servers, for
instance have now shrunk to the size of a single chip. We want to
make it easier to achieve the layout and behavior you want without
the need to struggle with complex scripts or having to hack layout
using tables and spacer gifs etc.</p>

<h3 id="ezmath" align="center"><em>An easy way to add Math to Web
pages</em></h3>

<p>In 1993 I first started work on how to incorporate mathematical
expressions into Web pages. This work led me to set up the W3C Math
working group which has produced the <a href="/Math">MathML</a>
specification. MathML is an XML application and very verbose. In
search of an easier to learn and more concise notation, I have been
inspired by how people say mathematical expressions when reading
aloud. The result is now available for downloading as a plugin and
standalone editing tool for the <a
href="http://www.w3.org/People/Raggett/EzMath">EzMath</a> notation
developed together with Davy Batsalle from ENST. EzMath is
particularly simple to use as well as providing a convenient way to
author MathML. Have a look and see how much smaller and more
obvious EzMath is compared to MathML! I later worked on a
reimplementation of EzMath with a filter for mapping XHTML+EZMath
to XHTML+MathML.</p>

<h3 align="center"><em>Easier ways to add style and behaviour to
Web pages</em></h3>

<p>I am interested in ideas for easier ways to apply style and
behaviour to HTML and XML documents. My approach has been to look
at ways to extend ECMAScript to combine extensible cascading style
rules (CSS) with object-oriented scripting. I sketched out the
ideas in a proposal called <a href="spice">Spice</a>, which was
officially submitted to W3C by Hewlett-Packard, and led to work
with IBM, Microsoft and Netscape in <a
href="http://www.ecma.ch/">ECMA</a> on a new edition of ECMAScript.
This has taken a long time to develop but is now nearing
completion.</p>

<p><img src="xhtmlbook.jpg" align="right" alt="book cover" border="0"
width="120" height="155" hspace="10" /></p>

<!--<h3 align="center"><em>"<a
href="http://www.wrox.com/Consumer/Store/Details.asp?ISBN=1861003439">
Beginning XHTML</a>"</em></h3>-->

<h3 align="center"><em>"Beginning XHTML"</em></h3>

<p>XHTML follows in the footsteps of HTML, combining the benefits
of its easy to understand vocabulary with the versatile syntax of
XML to create an Extensible HTML, which will be easily accessible
not only by today's desktop browsers, but by other equipment - such
as cell phones - without the processing power to interpret the now
lenient rules of HTML. Anyone who wants to learn how to create a
Web page will need to learn XHTML. Sadly this book is now out of
print.</p>

<br clear="all" /><img
src="html4.gif" alt="book cover" align="left" border="0"
width="120" height="147" hspace="10" />

<h3 align="center"><em>"Raggett on HTML 4"</em></h3>

<!--<h3 align="center"><em>"<a
href="http://cseng.aw.com/book/0,3828,0201178052,00.html">Raggett
on HTML 4</a>"</em></h3>-->

<p>'Raggett on HTML 4' was published (1998) by Addison Wesley, ISBN
0-201-17805-2. The intelligent person's guide to HTML 4, as written
by one of the chief architects of HTML, and editor of the HTML+,
3.0, 3.2 and 4.0 specifications. Here is
<a href="book4/ch01.html">Chapter 1 - introduction to the World
Wide Web</a>, and <a href="book4/ch02.html">Chapter 2 - a history of
HTML</a>.  See also these notes on <a href="the-early-days-of-the-Web.html">my
personal involvement with the early days</a>. Sadly this book too is
now out of print.<br clear="all" />
</p>

<h3 align="center"><em>Subsetting and Extending HTML</em></h3>

<p>The range of browser platforms is undergoing a massive expansion
with set-top boxes for televisions, handhelds, cellphones, voice
browsers and embedded devices as well as conventional desktop
systems. Defining HTML as the lowest common denominator of these
devices would fall far short of the potential for the upper end. As
a result, W3C has worked on ways to <a
href="/TR/xhtml-modularization/">modularize HTML</a> and how to
combine it with other tag sets, for instance <a
href="/Graphics/SVG">SVG</a> (W3C's web drawing standard), <a
href="/AudioVideo/">SMIL</a> (used for multimedia
synchronization), <a href="/Math/">MathML</a> (mathematical
expressions) and <a href="/RDF/">RDF</a> (used for representing
metadata).</p>

<p>A key ingredient in this, is the means to formally specify a
<b>document profile</b> that defines what tag sets can be used
together, what image formats, the level of style sheet support,
which scripting libraries can be used etc. The document profile
provides the basis for interoperability guarantees. It also makes
it feasible to provide transformation tools for converting content
from one profile to another.</p>

<p>I developed a way of formalizing document profiles as a set of
modular assertions, that break free of the limitations of document
type definitions (DTDs) as used in SGML and XML. The approach is
being named <a href="dtdgen/Docs/">Assertion Grammars</a>. An early
spin-off from this work is a tool for generating DTDs called
<b>dtdgen</b>. When I get time, I plan to combine this with ideas
developed for XForms, to produce a powerful new way to describe XML
document integrity constraints that bursts free of the static
nature of XML Schema, to cover dynamic constraints expressed in
fuctional and logical terms.</p>

<p>Much later in August 2006, when trying to write modular schemas
for an XML grammar for DOM events, I came up with a way to combine
assertion grammars with <a href="http://relaxng.org/">RelaxNG</a>.
The result is expressed in XML and allows you to write definitions
that extend earlier ones, but without the need to modify the definitions
they extend. This is in contrast to RelaxNG, which allows definitions
closer to the document's root element to refer to definitions that
are closer to the leaves in the document tree, but not the other way
around. The problem with the top down nature of most grammar formalisms
is that if you want to add a new definition, you can't just compose
sets of grammar rules, since the new definition has to be referenced
from the old, and that means changing the old definition. My
approach borrows from type definitions for object oriented programming
languages as well as from the tree regular expressions that form the
basis for RelaxNG. The new approach is called <a href="exert.html"
title="XML assertions"><strong>Exert</strong></a> as a contraction for XML
assertions.</p>

<!--
<h3 align="center"><em>Speeding up the Web!</em></h3>

<p>I am very much concerned with scaling issues for the Web. Right
now the Web is still in its infancy. Techniques that sort of work
today, won't work for tomorrow. My ideas are based around the
notion of service replication as a replacement for file caching.
DNS is a poor basis for naming resources and I am interested in
higher performance and more appropriate alternatives. With a
distributed approach based on cooperative resource sharing and load
balancing, perhaps we can find a way to make the web a more
effective medium for durable electronic records.</p>
-->

<!--
<p>When I formed the HTTP working group in 1994, I
tried to get the IETF to work on a next generation protocol, but
it has taken until now to get enough people interested in this.
W3C is currently working on <a
href="http://www.w3.org/Protocols/HTTP-NG/">HTTP-NG</a> as a
first step, but further work is needed before the service
distribution concept can be effectively realize.</p>
-->
<hr />
<p>Email: <a
href="mailto:dsr@w3.org">dsr@w3.org</a>, phone: +44&nbsp;1225
866 240 <!--mobile:&nbsp;+44&nbsp;7917&nbsp;839&nbsp;038 (GSM)--></p>
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